- Pyqt Signals And Slots Tutorials
- Pyqt Signals And Slots Tutorial Cheat
- Pyqt Signals And Slots Tutorial For Beginners
- Pyqt Signals And Slots Tutorial Key
In PyQt4 I have a main window which when the settings button is clicked opens the settings dialog
The above works and my SettingsDialog is displayed but I cant get the setPageIndex to work
Signals and Slots in PySide. From Qt Wiki (Redirected from Signals and slots in PySide) Redirect page. Jump to: navigation, search. PyQt5 Signals and slots; PyQt5 messagebox; PyQt5 textbox; PyQt5 positioning; PyQt5 menu; PyQt5 table; PyQt5 tabs; PyQt5 horizontal layout; PyQt5 grid layout; PyQt5 input dialogs; PyQt5 file dialogs; PyQt5 load image; PyQt5 drawing and pixels; PyQt5 color dialog; PyQt5 colors; Drag and drop; PyQt5 font dialog; PyQt5 matplotlib; Webkit browser. An introduction to creating PySide/PyQt signals and slots, using QObject. How signals and slots are useful, and what they can do when developing in PySide/PyQt.
The bookSettingsBtn is a QToolButton
And the settingsStackedWidget is a QStackedWidget
At this point I am pretty confused on signals and slots and nothing I have read clears this up - if anyone can point out what I am doing wrong above and also potentially direct me to a good (beginners) guide / tutorial on signals and slots it would be greatly appreciated
I would also like to know how to make setPageIndex work as follows:
I'm not sure why you're doing the following, but that's the issue:
SettingsDialog itself is a proper QDialog. You don't need to instantiate another QDialog.
Right now, you're creating an empty QDialog and then populate it with the same ui as SettingsDialog (i.e. setupUi(dialog)), then you show this dialog. But.. The signal connection is for SettingsDialog, and the dialog you're showing doesn't have that.
Basically, you don't need that extra QDialog at all. The following should be enough:
Pyqt Signals And Slots Tutorials
odoo v8 - Field(s) `arch` failed against a constraint: Invalid view definition
python,xml,view,odoo,add-on
You have made silly mistake in defining _columns. _colums is not valid dictionary name for fields structure. Replace this by _columns and restart service and update module. ..
Replace nodejs for python?
python,node.js,webserver
You might want to have a look at Tornado. It is well-documented and features built-in support for WebSockets. If you want to steer clear of the Tornado-framework, there are several Python implementations of Socket.io. Good luck!..
Sort when values are None or empty strings python
python,list,sorting,null
If you want the None and ' values to appear last, you can have your key function return a tuple, so the list is sorted by the natural order of that tuple. The tuple has the form (is_none, is_empty, value); this way, the tuple for a None value will be..
Parse text from a .txt file using csv module
python,python-2.7,parsing,csv
How about using Regular Expression def get_info(string_to_search): res_dict = {} import re find_type = re.compile('Type:[s]*[w]*') res = find_type.search(string_to_search) res_dict['Type'] = res.group(0).split(':')[1].strip() find_Status = re.compile('Status:[s]*[w]*') res = find_Status.search(string_to_search) res_dict['Status'] = res.group(0).split(':')[1].strip() find_date = re.compile('Date:[s]*[/0-9]*') res = find_date.search(string_to_search) res_dict['Date'] = res.group(0).split(':')[1].strip() res_dict['description'] =..
how to enable a entry by clicking a button in Tkinter?
python,tkinter
You need to use the configure method of each widget: def rakhi(): entry1.configure(state='normal') entry2.configure(state='normal') ..
Python recursive function not recursing
python,recursion
Afraid I don't know much about python, but I can probably help you with the algorithm. The encoding process repeats the following: multiply the current total by 17 add a value (a = 1, b = 2, .., z = 26) for the next letter to the total So at..
How to use template within Django template?
python,html,django,templates,django-1.4
You can use the include tag in order to supply the included template with a consistent variable name: For example: parent.html
REGEX python find previous string
python,regex,string
Updated: This will check for the existence of a sentence followed by special characters. It returns false if there are no special characters, and your original sentence is in capture group 1. Updated Regex101 Example r'(.*[w])([^w]+)' Alternatively (without a second capture group): Regex101 Example - no second capture group r'(.*[w])(?:[^w]+)'..
Peewee: reducing where conditionals break after a certain length
python,peewee
Try ..where(SomeTable.BIN.in_(big_list)) PeeWee has restrictions as to what can be used in their where clause in order to work with the library. http://docs.peewee-orm.com/en/latest/peewee/querying.html#query-operators..
How do variables inside python modules work?
python,module,python-module
The convention is to declare constants in modules as variables written in upper-case (Python style guide: https://www.python.org/dev/peps/pep-0008/#global-variable-names). But there's no way to prevent someone else to re-declare such a variable -- thus ignoring conventions -- when importing a module. There are two ways of working around this when importing modules..
Find the tf-idf score of specific words in documents using sklearn
python,scikit-learn,tf-idf
Yes. See .vocabulary_ on your fitted/transformed TF-IDF vectorizer. In [1]: from sklearn.datasets import fetch_20newsgroups In [2]: data = fetch_20newsgroups(categories=['rec.autos']) In [3]: from sklearn.feature_extraction.text import TfidfVectorizer In [4]: cv = TfidfVectorizer() In [5]: X = cv.fit_transform(data.data) In [6]: cv.vocabulary_ It is a dictionary of the form: {word : column index in..
SyntaxError: invalid syntax?
python,syntax
Check the code before the print line for errors. This can be caused by an error in a previous line; for example: def x(): y = [ print 'hello' x() This produces the following error: File 'E:Pythontest.py', line 14 print 'hello' ^ SyntaxError: invalid syntax When clearly the error is..
Inserting a variable in MongoDB specifying _id field
python,mongodb,pymongo
Insert only accepts a final document or an array of documents, and an optional object which contains additional options for the collection. db.collection.insert( , { // options writeConcern: , ordered: } ) You may want to add the _id to the document in advance, but..
Strange Behavior: Floating Point Error after Appending to List
python,python-2.7,behavior
Short answer: your correct doesn't work. Long answer: The binary floating-point formats in ubiquitous use in modern computers and programming languages cannot represent most numbers like 0.1, just like no terminating decimal representation can represent 1/3. Instead, when you write 0.1 in your source code, Python automatically translates this to..
Pandas - Dropping multiple empty columns
python,pandas
You can just subscript the columns: df = df[df.columns[:11]] This will return just the first 11 columns or you can do: df.drop(df.columns[11:], axis=1) To drop all the columns after the 11th one..
group indices of list in list of lists
python,list
Use collections.OrderedDict: from collections import OrderedDict od = OrderedDict() lst = [2, 0, 1, 1, 3, 2, 1, 2] for i, x in enumerate(lst): od.setdefault(x, []).append(i) .. >>> od.values() [[0, 5, 7], [1], [2, 3, 6], [4]] ..
sys.argv in a windows environment
python,windows,python-3.x
You are calling the script wrong Bring up a cmd (command line prompt) and type: cd C:/Users/user/PycharmProjects/helloWorld/ module_using_sys.py we are arguments And you will get the correct output..
Spring-integration scripting with Python
python,spring-integration,jython
This is a bug in Spring Integration; I have opened a JIRA Issue. if (variables != null) { result = scriptEngine.eval(script, new SimpleBindings(variables)); } else { result = scriptEngine.eval(script); } When the first branch of the if test is taken, the result variable is added to the SimpleBindings object, and..
Inconsistency between gaussian_kde and density integral sum
python,numpy,kernel-density
As stated in my comment, this is an issue with kernel density support. The Gaussian kernel has infinite support. Even fit on data with a specific range the range of the Gaussian kernel will be from negative to positive infinity. That being said the large majority of the density will..
How to put an image on another image in python, using ImageTk?
python,user-interface,tkinter
Just use photoshop or G.I.M.P. I assure you, doing it that way will be much simpler and less redundant than essentially getting Tkinter to photo edit for you (not to mention what you're talking about is just bad practice when it comes to coding) Anyways, I guess if you really..
represent an index inside a list as x,y in python
python,list,numpy,multidimensional-array
According to documentation of numpy.reshape , it returns a new array object with the new shape specified by the parameters (given that, with the new shape, the amount of elements in the array remain unchanged) , without changing the shape of the original object, so when you are calling the..
How to check for multiple attributes in a list
python,python-2.7
You can create a set holding the different IDs and then compare the size of that set to the total number of quests. The difference tells you how many IDs are duplicated. Same for names. Something like this (untested): def test_quests(quests): num_total = len(quests) different_ids = len(set((q.ID for q in..
In sklearn, does a fitted pipeline reapply every transform?
python,scikit-learn,pipeline,feature-selection
The pipeline calls transform on the preprocessing and feature selection steps if you call pl.predict. That means that the features selected in training will be selected from the test data (the only thing that makes sense here). It is unclear what you mean by 'apply' here. Nothing new will be..
Sum of two variables in RobotFramework
python,automated-tests,robotframework
By default variables are string in Robot. So your first two statements are assigning strings like 'xx,yy' to your vars. Then 'evaluate' just execute your statement as Python would do. So, adding your two strings with commas will produce a list: $ python >>> 1,2+3,4 (1, 5, 4) So you..
How does the class_weight parameter in scikit-learn work?
python,scikit-learn
First off, it might not be good to just go by recall alone. You can simply achieve a recall of 100% by classifying everything as the positive class. I usually suggest using AUC for selecting parameters, and then finding a threshold for the operating point (say a given precision level)..
Matplotlib: Plot the result of an SQL query
python,sql,matplotlib,plot
Take this for a starter code : import numpy as np import matplotlib.pyplot as plt from sqlalchemy import create_engine import _mssql fig = plt.figure() ax = fig.add_subplot(111) engine = create_engine('mssql+pymssql://**:****@127.0.0.1:1433/AffectV_Test') connection = engine.connect() result = connection.execute('SELECT Campaign_id, SUM(Count) AS Total_Count FROM Impressions GROUP BY Campaign_id') ## the data data =..
trying to understand LSH through the sample python code
python,similarity,locality-sensitive-hash
a. It's a left shift: https://docs.python.org/2/reference/expressions.html#shifting-operations It shifts the bits one to the left. b. Note that ^ is not the 'to the power of' but 'bitwise XOR' in Python. c. As the comment states: it defines 'number of bits per signature' as 2**10 → 1024 d. The lines calculate..
How to remove structure with python from this case?python,python-2.7
It's complicated to use regex, a stupid way I suggested: def remove_table(s): left_index = s.find('') if -1 left_index: return s right_index = s.find('
Python np.delete issue
python,numpy
Don't call np.delete in a loop. It would be quicker to use boolean indexing: In [6]: A[X.astype(bool).any(axis=0)] Out[6]: array([[3, 4, 5]]) X.astype(bool) turns 0 into False and any non-zero value into True: In [9]: X.astype(bool).any(axis=0) Out[9]: array([False, True, False], dtype=bool) the call to .any(axis=0) returns True if any value in..
ctypes error AttributeError symbol not found, OS X 10.7.5
python,c++,ctypes
Your first problem is C++ name mangling. If you run nm on your .so file you will get something like this: nm test.so 0000000000000f40 T __Z3funv U _printf U dyld_stub_binder If you mark it as C style when compiled with C++: #ifdef __cplusplus extern 'C' char fun() #else char fun(void)..
Python: histogram/ binning data from 2 arrays.
python,histogram,large-files
if you only need to do this for a handful of points, you could do something like this. If intensites and radius are numpy arrays of your data: bin_width = 0.1 # Depending on how narrow you want your bins def get_avg(rad): average_intensity = intensities[(radius>=rad-bin_width/2.) & (radius
Displaying a 32-bit image with NaN values (ImageJ)
python,image-processing,imagej
The display range of your image might not be set correctly. Try outputImp.resetDisplayRange() or outputImp.setDisplayRange(Stats.min, Stats.max) See the ImagePlus javadoc for more info..
Count function counting only last line of my list
python,python-2.7
I don't know what you are exactly trying to achieve but if you are trying to count R and K in the string there are more elegant ways to achieve it. But for your reference I had modified your code. N = int(raw_input()) s = [] for i in range(N):..
Using counter on array for one value while keeping index of other values
python,collections
To count how often one value occurs and at the same time you want to select those values, you'd simply select those values and count how many you selected: fruits = [f for f in foods if f[0] 'fruit'] fruit_count = len(fruits) If you need to do this for..
Django: html without CSS and the right text
python,html,css,django,url
Are you using the {% load staticfiles %} in your templates?
Pandas Dataframe Complex Calculation
python,python-2.7,pandas,dataframes
I believe the following does what you want: In [24]: df['New_Col'] = df['ActualCitations']/pd.rolling_sum(df['totalPubs'].shift(), window=2) df Out[24]: Year totalPubs ActualCitations New_Col 0 1994 71 191.002034 NaN 1 1995 77 2763.911781 NaN 2 1996 69 2022.374474 13.664692 3 1997 78 3393.094951 23.240376 So the above uses rolling_sum and shift to generate the..
Identify that a string could be a datetime object
python,regex,algorithm,python-2.7,datetime
What about fuzzyparsers: Sample inputs: jan 12, 2003 jan 5 2004-3-5 +34 -- 34 days in the future (relative to todays date) -4 -- 4 days in the past (relative to todays date) Example usage: >>> from fuzzyparsers import parse_date >>> parse_date('jun 17 2010') # my youngest son's birthday datetime.date(2010,..
Python Popen - wait vs communicate vs CalledProcessError
python,python-2.7,error-handling,popen
about the deadlock: It is safe to use stdout=PIPE and wait() together iff you read from the pipe. .communicate() does the reading and calls wait() for you about the memory: if the output can be unlimited then you should not use .communicate() that accumulates all output in memory. what..
Python: can't access newly defined environment variables
python,bash,environment-variables
After updating your .bashrc, perform source ~/.bashrc to apply the changes. Poker score app ios. Also, merge the two BONSAI-related calls into one: export BONSAI=/home/me/Utils/bonsai_v3.2 UPDATE: It was actually an attempt to update the environment for some Eclipse-based IDE. This is a different usecase altogether. It should be described in the Eclipse help. Also,..
MySQLdb Python - Still getting error when using CREATE TABLE IF NOT EXISTS
python,mysql
MySQL is actually throwing a warning rather that an error. You can suppress mysql warnings like this : import MySQLdb as mdb from warnings import filterwarnings filterwarnings('ignore', category = mdb.Warning) Now the mysql warnings will be gone. But mysql errors will be shown as usual Read more about warnings at..
Twilio Client Python not Working in IOS Browser
javascript,python,ios,flask,twilio
Twilio developer evangelist here. Twilio Client uses WebRTC and falls back to Flash in order to make web browsers into phones. Unfortunately Safari on iOS supports neither WebRTC nor Flash so Twilio Client cannot work within any browser on iOS. It is possible to build an iOS application to use..
How to change the IP address of Amazon EC2 instance using boto library
python,amazon-web-services,boto
Make sure you have set properly with ~/.boto and connect to aws, have the boto module ready in python. If not, go through this first: Getting Started with Boto For example, you need assign a new EIP 54.12.23.34 to the instance i-12345678 Make sure, EIP has been allocated(existed) and you..
C++ & Qt: Random string from an array area
c++,arrays,string,qt,random
You should use the random header. #include std::default_random_engine generator; std::uniform_int_distribution dist(0, 5); int StringIndex = dist(generator); std::string ChosenString = characters[StringIndex]; The above will generate a random index into your array. If you want to limit the range, change the constructor of dist, for example (dist(0,2) would only allow for..
SQLAlchemy. 2 different relationships for 1 column
python,sqlalchemy
I'm afraid you can't do it like this. I suggest you have just one relationship users and validate the insert queries.
Create an exe with Python 3.4 using cx_Freeze
python,python-3.4,cx-freeze
Since you want to convert python script to exe have a look at py2exe
How do I read this list and parse it?
python,list
Your list contains one dictionary you can access the data inside like this : >>> yourlist[0]['popularity'] 2354 [0] for the first item in the list (the dictionary). ['popularity'] to get the value associated to the key 'popularity' in the dictionary..
The event loop is already running
python,python-3.x,pyqt,pyqt4
I think the problem is with your start.py file. You have a function refreshgui which re imports start.py import will run every part of the code in the file. It is customary to wrap the main functionality in an 'if __name__ '__main__': to prevent code from being run on..
Python - Opening and changing large text files
python,replace,out-of-memory,large-files
You need to read one bite per iteration, analyze it and then write to another file or to sys.stdout. Try this code: mesh = open('file.mesh', 'r') mesh_out = open('file-1.mesh', 'w') c = mesh.read(1) if c: mesh_out.write('{') else: exit(0) while True: c = mesh.read(1) if c ': break if c..
Can't get value from xpath python
python,html,xpath,web-scraping,html-parsing
The values in the table are generated with the help of javascript being executed in the browser. One option to approach it is to automate a browser via selenium, e.g. a headless PhantomJS: >>> from selenium import webdriver >>> >>> driver = webdriver.PhantomJS() >>> driver.get('http://www.tabele-kalorii.pl/kalorie,Actimel-cytryna-miod-Danone.html') >>> >>> table = driver.find_element_by_xpath(u'//table[tbody/tr/td/h3..
Calling function and passing arguments multiple times
python,function,loops
a,b,c = 1,2,3 while i
QGIS Tutorials
This tutorial is part of our QGIS tutorial series:
This is a brief explanation of the concept of signal and slot in PyQt5, which is the GUI framework for QGIS plugins.
In summary, this very much resembles events and callbacks in JavaScript. It's an asynchronous mechanism to let one part of a program know when another part of a program was updated, which is a most crucial concept in GUI programming. You master signal/slot, you master a whole lot about plugin development in QGIS.
General concept
Generally a signal is a trigger which can be emitted (hence the term signal) and carry an arbitrary amount of information when it is emitted.
The signal can be connected to a slot, which needs to be Python callable (in other words, a method or a class, anything implementing the __call__ magic), which can be any arbitrary function. The slot can accept the information which is emitted by the signal to process it further.
This is useful when one object needs to know about the actions of another object. For instance, if your plugin features a button that should paste the clipboard contents into a text field, then your plugin would need to know which function to call once the button is clicked. This is typically done via signal and slot.
I would also like to know how to make setPageIndex work as follows:
I'm not sure why you're doing the following, but that's the issue:
SettingsDialog itself is a proper QDialog. You don't need to instantiate another QDialog.
Right now, you're creating an empty QDialog and then populate it with the same ui as SettingsDialog (i.e. setupUi(dialog)), then you show this dialog. But.. The signal connection is for SettingsDialog, and the dialog you're showing doesn't have that.
Basically, you don't need that extra QDialog at all. The following should be enough:
Pyqt Signals And Slots Tutorials
odoo v8 - Field(s) `arch` failed against a constraint: Invalid view definition
python,xml,view,odoo,add-on
You have made silly mistake in defining _columns. _colums is not valid dictionary name for fields structure. Replace this by _columns and restart service and update module. ..
Replace nodejs for python?
python,node.js,webserver
You might want to have a look at Tornado. It is well-documented and features built-in support for WebSockets. If you want to steer clear of the Tornado-framework, there are several Python implementations of Socket.io. Good luck!..
Sort when values are None or empty strings python
python,list,sorting,null
If you want the None and ' values to appear last, you can have your key function return a tuple, so the list is sorted by the natural order of that tuple. The tuple has the form (is_none, is_empty, value); this way, the tuple for a None value will be..
Parse text from a .txt file using csv module
python,python-2.7,parsing,csv
How about using Regular Expression def get_info(string_to_search): res_dict = {} import re find_type = re.compile('Type:[s]*[w]*') res = find_type.search(string_to_search) res_dict['Type'] = res.group(0).split(':')[1].strip() find_Status = re.compile('Status:[s]*[w]*') res = find_Status.search(string_to_search) res_dict['Status'] = res.group(0).split(':')[1].strip() find_date = re.compile('Date:[s]*[/0-9]*') res = find_date.search(string_to_search) res_dict['Date'] = res.group(0).split(':')[1].strip() res_dict['description'] =..
how to enable a entry by clicking a button in Tkinter?
python,tkinter
You need to use the configure method of each widget: def rakhi(): entry1.configure(state='normal') entry2.configure(state='normal') ..
Python recursive function not recursing
python,recursion
Afraid I don't know much about python, but I can probably help you with the algorithm. The encoding process repeats the following: multiply the current total by 17 add a value (a = 1, b = 2, .., z = 26) for the next letter to the total So at..
How to use template within Django template?
python,html,django,templates,django-1.4
You can use the include tag in order to supply the included template with a consistent variable name: For example: parent.html
REGEX python find previous string
python,regex,string
Updated: This will check for the existence of a sentence followed by special characters. It returns false if there are no special characters, and your original sentence is in capture group 1. Updated Regex101 Example r'(.*[w])([^w]+)' Alternatively (without a second capture group): Regex101 Example - no second capture group r'(.*[w])(?:[^w]+)'..
Peewee: reducing where conditionals break after a certain length
python,peewee
Try ..where(SomeTable.BIN.in_(big_list)) PeeWee has restrictions as to what can be used in their where clause in order to work with the library. http://docs.peewee-orm.com/en/latest/peewee/querying.html#query-operators..
How do variables inside python modules work?
python,module,python-module
The convention is to declare constants in modules as variables written in upper-case (Python style guide: https://www.python.org/dev/peps/pep-0008/#global-variable-names). But there's no way to prevent someone else to re-declare such a variable -- thus ignoring conventions -- when importing a module. There are two ways of working around this when importing modules..
Find the tf-idf score of specific words in documents using sklearn
python,scikit-learn,tf-idf
Yes. See .vocabulary_ on your fitted/transformed TF-IDF vectorizer. In [1]: from sklearn.datasets import fetch_20newsgroups In [2]: data = fetch_20newsgroups(categories=['rec.autos']) In [3]: from sklearn.feature_extraction.text import TfidfVectorizer In [4]: cv = TfidfVectorizer() In [5]: X = cv.fit_transform(data.data) In [6]: cv.vocabulary_ It is a dictionary of the form: {word : column index in..
SyntaxError: invalid syntax?
python,syntax
Check the code before the print line for errors. This can be caused by an error in a previous line; for example: def x(): y = [ print 'hello' x() This produces the following error: File 'E:Pythontest.py', line 14 print 'hello' ^ SyntaxError: invalid syntax When clearly the error is..
Inserting a variable in MongoDB specifying _id field
python,mongodb,pymongo
Insert only accepts a final document or an array of documents, and an optional object which contains additional options for the collection. db.collection.insert( , { // options writeConcern: , ordered: } ) You may want to add the _id to the document in advance, but..
Strange Behavior: Floating Point Error after Appending to List
python,python-2.7,behavior
Short answer: your correct doesn't work. Long answer: The binary floating-point formats in ubiquitous use in modern computers and programming languages cannot represent most numbers like 0.1, just like no terminating decimal representation can represent 1/3. Instead, when you write 0.1 in your source code, Python automatically translates this to..
Pandas - Dropping multiple empty columns
python,pandas
You can just subscript the columns: df = df[df.columns[:11]] This will return just the first 11 columns or you can do: df.drop(df.columns[11:], axis=1) To drop all the columns after the 11th one..
group indices of list in list of lists
python,list
Use collections.OrderedDict: from collections import OrderedDict od = OrderedDict() lst = [2, 0, 1, 1, 3, 2, 1, 2] for i, x in enumerate(lst): od.setdefault(x, []).append(i) .. >>> od.values() [[0, 5, 7], [1], [2, 3, 6], [4]] ..
sys.argv in a windows environment
python,windows,python-3.x
You are calling the script wrong Bring up a cmd (command line prompt) and type: cd C:/Users/user/PycharmProjects/helloWorld/ module_using_sys.py we are arguments And you will get the correct output..
Spring-integration scripting with Python
python,spring-integration,jython
This is a bug in Spring Integration; I have opened a JIRA Issue. if (variables != null) { result = scriptEngine.eval(script, new SimpleBindings(variables)); } else { result = scriptEngine.eval(script); } When the first branch of the if test is taken, the result variable is added to the SimpleBindings object, and..
Inconsistency between gaussian_kde and density integral sum
python,numpy,kernel-density
As stated in my comment, this is an issue with kernel density support. The Gaussian kernel has infinite support. Even fit on data with a specific range the range of the Gaussian kernel will be from negative to positive infinity. That being said the large majority of the density will..
How to put an image on another image in python, using ImageTk?
python,user-interface,tkinter
Just use photoshop or G.I.M.P. I assure you, doing it that way will be much simpler and less redundant than essentially getting Tkinter to photo edit for you (not to mention what you're talking about is just bad practice when it comes to coding) Anyways, I guess if you really..
represent an index inside a list as x,y in python
python,list,numpy,multidimensional-array
According to documentation of numpy.reshape , it returns a new array object with the new shape specified by the parameters (given that, with the new shape, the amount of elements in the array remain unchanged) , without changing the shape of the original object, so when you are calling the..
How to check for multiple attributes in a list
python,python-2.7
You can create a set holding the different IDs and then compare the size of that set to the total number of quests. The difference tells you how many IDs are duplicated. Same for names. Something like this (untested): def test_quests(quests): num_total = len(quests) different_ids = len(set((q.ID for q in..
In sklearn, does a fitted pipeline reapply every transform?
python,scikit-learn,pipeline,feature-selection
The pipeline calls transform on the preprocessing and feature selection steps if you call pl.predict. That means that the features selected in training will be selected from the test data (the only thing that makes sense here). It is unclear what you mean by 'apply' here. Nothing new will be..
Sum of two variables in RobotFramework
python,automated-tests,robotframework
By default variables are string in Robot. So your first two statements are assigning strings like 'xx,yy' to your vars. Then 'evaluate' just execute your statement as Python would do. So, adding your two strings with commas will produce a list: $ python >>> 1,2+3,4 (1, 5, 4) So you..
How does the class_weight parameter in scikit-learn work?
python,scikit-learn
First off, it might not be good to just go by recall alone. You can simply achieve a recall of 100% by classifying everything as the positive class. I usually suggest using AUC for selecting parameters, and then finding a threshold for the operating point (say a given precision level)..
Matplotlib: Plot the result of an SQL query
python,sql,matplotlib,plot
Take this for a starter code : import numpy as np import matplotlib.pyplot as plt from sqlalchemy import create_engine import _mssql fig = plt.figure() ax = fig.add_subplot(111) engine = create_engine('mssql+pymssql://**:****@127.0.0.1:1433/AffectV_Test') connection = engine.connect() result = connection.execute('SELECT Campaign_id, SUM(Count) AS Total_Count FROM Impressions GROUP BY Campaign_id') ## the data data =..
trying to understand LSH through the sample python code
python,similarity,locality-sensitive-hash
a. It's a left shift: https://docs.python.org/2/reference/expressions.html#shifting-operations It shifts the bits one to the left. b. Note that ^ is not the 'to the power of' but 'bitwise XOR' in Python. c. As the comment states: it defines 'number of bits per signature' as 2**10 → 1024 d. The lines calculate..
How to remove structure with python from this case?python,python-2.7
It's complicated to use regex, a stupid way I suggested: def remove_table(s): left_index = s.find('') if -1 left_index: return s right_index = s.find('
Python np.delete issue
python,numpy
Don't call np.delete in a loop. It would be quicker to use boolean indexing: In [6]: A[X.astype(bool).any(axis=0)] Out[6]: array([[3, 4, 5]]) X.astype(bool) turns 0 into False and any non-zero value into True: In [9]: X.astype(bool).any(axis=0) Out[9]: array([False, True, False], dtype=bool) the call to .any(axis=0) returns True if any value in..
ctypes error AttributeError symbol not found, OS X 10.7.5
python,c++,ctypes
Your first problem is C++ name mangling. If you run nm on your .so file you will get something like this: nm test.so 0000000000000f40 T __Z3funv U _printf U dyld_stub_binder If you mark it as C style when compiled with C++: #ifdef __cplusplus extern 'C' char fun() #else char fun(void)..
Python: histogram/ binning data from 2 arrays.
python,histogram,large-files
if you only need to do this for a handful of points, you could do something like this. If intensites and radius are numpy arrays of your data: bin_width = 0.1 # Depending on how narrow you want your bins def get_avg(rad): average_intensity = intensities[(radius>=rad-bin_width/2.) & (radius
Displaying a 32-bit image with NaN values (ImageJ)
python,image-processing,imagej
The display range of your image might not be set correctly. Try outputImp.resetDisplayRange() or outputImp.setDisplayRange(Stats.min, Stats.max) See the ImagePlus javadoc for more info..
Count function counting only last line of my list
python,python-2.7
I don't know what you are exactly trying to achieve but if you are trying to count R and K in the string there are more elegant ways to achieve it. But for your reference I had modified your code. N = int(raw_input()) s = [] for i in range(N):..
Using counter on array for one value while keeping index of other values
python,collections
To count how often one value occurs and at the same time you want to select those values, you'd simply select those values and count how many you selected: fruits = [f for f in foods if f[0] 'fruit'] fruit_count = len(fruits) If you need to do this for..
Django: html without CSS and the right text
python,html,css,django,url
Are you using the {% load staticfiles %} in your templates?
Pandas Dataframe Complex Calculation
python,python-2.7,pandas,dataframes
I believe the following does what you want: In [24]: df['New_Col'] = df['ActualCitations']/pd.rolling_sum(df['totalPubs'].shift(), window=2) df Out[24]: Year totalPubs ActualCitations New_Col 0 1994 71 191.002034 NaN 1 1995 77 2763.911781 NaN 2 1996 69 2022.374474 13.664692 3 1997 78 3393.094951 23.240376 So the above uses rolling_sum and shift to generate the..
Identify that a string could be a datetime object
python,regex,algorithm,python-2.7,datetime
What about fuzzyparsers: Sample inputs: jan 12, 2003 jan 5 2004-3-5 +34 -- 34 days in the future (relative to todays date) -4 -- 4 days in the past (relative to todays date) Example usage: >>> from fuzzyparsers import parse_date >>> parse_date('jun 17 2010') # my youngest son's birthday datetime.date(2010,..
Python Popen - wait vs communicate vs CalledProcessError
python,python-2.7,error-handling,popen
about the deadlock: It is safe to use stdout=PIPE and wait() together iff you read from the pipe. .communicate() does the reading and calls wait() for you about the memory: if the output can be unlimited then you should not use .communicate() that accumulates all output in memory. what..
Python: can't access newly defined environment variables
python,bash,environment-variables
After updating your .bashrc, perform source ~/.bashrc to apply the changes. Poker score app ios. Also, merge the two BONSAI-related calls into one: export BONSAI=/home/me/Utils/bonsai_v3.2 UPDATE: It was actually an attempt to update the environment for some Eclipse-based IDE. This is a different usecase altogether. It should be described in the Eclipse help. Also,..
MySQLdb Python - Still getting error when using CREATE TABLE IF NOT EXISTS
python,mysql
MySQL is actually throwing a warning rather that an error. You can suppress mysql warnings like this : import MySQLdb as mdb from warnings import filterwarnings filterwarnings('ignore', category = mdb.Warning) Now the mysql warnings will be gone. But mysql errors will be shown as usual Read more about warnings at..
Twilio Client Python not Working in IOS Browser
javascript,python,ios,flask,twilio
Twilio developer evangelist here. Twilio Client uses WebRTC and falls back to Flash in order to make web browsers into phones. Unfortunately Safari on iOS supports neither WebRTC nor Flash so Twilio Client cannot work within any browser on iOS. It is possible to build an iOS application to use..
How to change the IP address of Amazon EC2 instance using boto library
python,amazon-web-services,boto
Make sure you have set properly with ~/.boto and connect to aws, have the boto module ready in python. If not, go through this first: Getting Started with Boto For example, you need assign a new EIP 54.12.23.34 to the instance i-12345678 Make sure, EIP has been allocated(existed) and you..
C++ & Qt: Random string from an array area
c++,arrays,string,qt,random
You should use the random header. #include std::default_random_engine generator; std::uniform_int_distribution dist(0, 5); int StringIndex = dist(generator); std::string ChosenString = characters[StringIndex]; The above will generate a random index into your array. If you want to limit the range, change the constructor of dist, for example (dist(0,2) would only allow for..
SQLAlchemy. 2 different relationships for 1 column
python,sqlalchemy
I'm afraid you can't do it like this. I suggest you have just one relationship users and validate the insert queries.
Create an exe with Python 3.4 using cx_Freeze
python,python-3.4,cx-freeze
Since you want to convert python script to exe have a look at py2exe
How do I read this list and parse it?
python,list
Your list contains one dictionary you can access the data inside like this : >>> yourlist[0]['popularity'] 2354 [0] for the first item in the list (the dictionary). ['popularity'] to get the value associated to the key 'popularity' in the dictionary..
The event loop is already running
python,python-3.x,pyqt,pyqt4
I think the problem is with your start.py file. You have a function refreshgui which re imports start.py import will run every part of the code in the file. It is customary to wrap the main functionality in an 'if __name__ '__main__': to prevent code from being run on..
Python - Opening and changing large text files
python,replace,out-of-memory,large-files
You need to read one bite per iteration, analyze it and then write to another file or to sys.stdout. Try this code: mesh = open('file.mesh', 'r') mesh_out = open('file-1.mesh', 'w') c = mesh.read(1) if c: mesh_out.write('{') else: exit(0) while True: c = mesh.read(1) if c ': break if c..
Can't get value from xpath python
python,html,xpath,web-scraping,html-parsing
The values in the table are generated with the help of javascript being executed in the browser. One option to approach it is to automate a browser via selenium, e.g. a headless PhantomJS: >>> from selenium import webdriver >>> >>> driver = webdriver.PhantomJS() >>> driver.get('http://www.tabele-kalorii.pl/kalorie,Actimel-cytryna-miod-Danone.html') >>> >>> table = driver.find_element_by_xpath(u'//table[tbody/tr/td/h3..
Calling function and passing arguments multiple times
python,function,loops
a,b,c = 1,2,3 while i
QGIS Tutorials
This tutorial is part of our QGIS tutorial series:
This is a brief explanation of the concept of signal and slot in PyQt5, which is the GUI framework for QGIS plugins.
In summary, this very much resembles events and callbacks in JavaScript. It's an asynchronous mechanism to let one part of a program know when another part of a program was updated, which is a most crucial concept in GUI programming. You master signal/slot, you master a whole lot about plugin development in QGIS.
General concept
Generally a signal is a trigger which can be emitted (hence the term signal) and carry an arbitrary amount of information when it is emitted.
The signal can be connected to a slot, which needs to be Python callable (in other words, a method or a class, anything implementing the __call__ magic), which can be any arbitrary function. The slot can accept the information which is emitted by the signal to process it further.
This is useful when one object needs to know about the actions of another object. For instance, if your plugin features a button that should paste the clipboard contents into a text field, then your plugin would need to know which function to call once the button is clicked. This is typically done via signal and slot.
Signal
A signalhas to be a class attribute of a descendant of QObject. Any QGIS widget and almost all GUI classes are descendants of QObject (i.e. have QObject as the very basic parent class) and they all come with predefined signals, such as QgsFilterLineEdit's valueChanged signal, which is triggered when a user changes the text of the widget.
Definition
A signal has the general definition of PyQt5.QtCore.pyqtSignal(types), where types will be the data type(s) a signal can emit:
- any basic Python data type (
int,str,listetc.) or C++ type. In the latter case it needs to be defined as a string, e.g.pyqtSignal(int)orpyqtSignal('QgsPointXY') - multiple Python or C++ types, which will emit several values, e.g.
pyqtSignal(int, str)will take two arguments - multiple sequences, which will create multiple versions of the signal, i.e. signal overloads, e.g.
pyqtSignal([int], ['QgsPointXY'])
The first two options are fairly easy to grasp. However, the latter is a little more mysterious. Basically, overloaded signatures are a way to define the same object or class in multiple ways (you might call it Schrödinger's signal). The concept of overloaded class definitions is not really a thing in Python, though it can be done. If you define a signal with overloaded signatures, it's like you're creating the same object multiple times with different arguments, e.g. the example above would translate to:
This method to define a signal is a little more elaborate as we'll see soon, but very handy.
Methods
connect()
This method connects the signal to a slot. I.e. the signal can connect to a function, which takes its arguments and does something with them. For all practical purposes, you'll only need to pass the slot function to connect(). Each signal can connect to an arbitrary amount of slot functions.
disconnect()
Pyqt Signals And Slots Tutorial Cheat
Often you want to disconnect a slot from its signal to control whether the slot function should still be executed when the signal is triggered. You can either pass the specific slot function or nothing, in which case all slots for the signal will be disconnected.
emit()
When called, it emits values of the data types you specified when defining the signal (if any). These values have to be in the same order as in the definition, i.e. if pyqtSignal(int, str) was the definition, the signal needs to e.g. emit(4, 'blabla'), not emit('blabla', 4).
Examples
Let's see how this would work with more practical examples. To more relate to QGIS plugins, I'll use a similar (harshly abstracted) barebone structure as in our Interactive QGIS Plugin tutorial to depict the general usage when e.g. defining a new Map Tool (QgsMapTool).
Simple Example
This is only non-working pseudo-code, which will just demonstrate the general usage. A map tool is created which implements a canvasReleaseEvent event emitting a custom signal when triggered. This signal connects to a custom slot function in the main plugin code.
So, this hypothetical plugin would capture the point clicked by a user upon releasing the mouse button and print the WKT (Well Known Text) representation of that point to the Python console. Not very useful, I know, but I hope it gets the point across.
Overloaded signal example
Let's get a little fancier and say we want to print the distance of that point to our location when we click the mouse, but the WKT representation when we release the mouse button.
We can achieve this with the exact same signal if we define it with an overloaded signature. Yep, finally seeing how a Schrödinger's signal can work:
We now defined another canvasPressEvent, which will be triggered if the user presses the map canvas while the NewMapTool is active.
Since we defined our canvasClicked event now with the overloaded signature pyqtSignal([int], ['QgsPointXY']), we need to watch out that we only call the right signature for connect() and emit(). If we would omit the specific signature when calling these functions, they would use the first signature they find, which would be int in this case.
Pyqt Signals And Slots Tutorial For Beginners
We connected both signatures to separate functions. Now, when the user clicks in the map canvas, the distance of the point to 13.413513, 52.491019 will be printed (*), when he releases the mouse button, the point's WKT representation will be printed.
Pyqt Signals And Slots Tutorial Key
Be aware however, that overloaded signatures have a catch: the Python data types in the pyqtSignal definition are converted to C++ types and some combinations can lead to undesired outcomes. E.g. pyqtSignal(, [dict]) will be converted to the same C++ data type. Calling emit() or connect() on the dict signature will be interpreted as calling the method on the list signature instead.
(*) Note, that those coordinates are in X, Y WGS84. The point captured by the canvasPressEvent depends on the map canvas CRS which is likely different, so you'd need to transform. Even if it were WGS84, the distance would be in degrees.
