I have a validator function as part of a bigger program which is fifty lines long which returns True or False when you give it a string. For a certain string, it is currently returning False, and I don't which of the many return statements is firing. I can open the Python Console of the interpreter and import the function then give it its argument, but not see on which line it is returning False. Would rather not alter the main program to feed it its argument, would also rather not set breakpoints in the program for this. Is it possible in PyCharm to isolate a function, give it your own custom argument and then step through it line by line?
Am using PyCharm version 2018.2.4
Is it possible in PyCharm to isolate a function, give it your own custom argument and then step through it line by line?
No, it's not unless you create another file and write something like tests there
By clicking on left side of each line you can declare a breakpoint on the line like this:
Then you can go to debug tool window and click on the green play button
More about debuging using PyCharm
Also you can use python's breakpoint()
It is added as a built-in function in Python 3.7 but u can import it to your file on Python's 3.7-
Related
I am very new to python programming and debugging in pycharm. I want to find the value of a particular variable inside a if condition and have set a breakpoint , however the debugger shows that the variables are not available. Below is the screenshot of the code and the debugger:
I was facing the same issue and I fixed it by going through following steps :-
On the bottom left corner of your pycharm IDE, you will a settings option, click there and then go to "variable loading policy" and set this option to "on demand".
Hope it helps you.
It is because you're code isn't running yet. The print(...) line is inside the function, instead of outside the function. Your code can only run if something outside a function does something.
Fix: Just remove the tab in front of the print statement. Like so:
def factor(n):
# Your function body ...
for (...)
# Somewhere here is the return statement
print(factor(25)) # See the start of this `print` is inline with the `def`
If I testing my codes on IDLE the autocomplete its works but if I open a new file don't.
See there pictures below:
I just press CTRL + SPACE.
So.. don't work in this case:
I'll think there are some configuration for solve this, any one knows?
Python idle doesn't work that way. You get autocomplete in idle shell because values are deduced in every run. When you use files your program is not evaluated until you run. Because you can assign any type to a variable at run time, there is no way for idle to confirm the type of variable.
Understand with an example
>> a = dict()
>> a = set()
>> a. # <-- autocomplete knows type of a is set
but the same code in a file
a = dict()
a = set()
a. # <-- How does idle come to know what this variable is without running
but when you run this file once your global variables will show autocomplete feature, but not the local scope variables.
Have you tried saving the script as a *.py file before trying to use IDLE's autocomplete?
More than that, have you considered using a text editor with Python plugins, like Sublime Text and Atom? Or even a python-compatible IDE, like PyCharm, Spyder or even JupyterNotebook.
Please excuse what I know is an incredibly basic question that I have nevertheless been unable to resolve on my own.
I'm trying to switch over my data analysis from Matlab to Python, and I'm struggling with something very basic: in Matlab, I write a function in the editor, and to use that function I simply call it from the command line, or within other functions. The function that I compose in the matlab editor is given a name at the function definition line, and it's generally best for the function name to match the .m file name to avoid confusion.
I don't understand how functions differ in Python, because I have not been successful translating the same approach there.
For instance, if I write a function in the Python editor (I'm using Python 2.7 and Spyder), simply saving the .py file and calling it by its name from the Python terminal does not work. I get a "function not defined" error. However, if I execute the function within Spyder's editor (using the "run file" button), not only does the code execute properly, from that point on the function is also call-able directly from the terminal.
So...what am I doing wrong? I fully appreciate that using Python isn't going to be identical to Matlab in every way, but it seems that what I'm trying to do isn't unreasonable. I simply want to be able to write functions and call them from the python command line, without having to run each and every one through the editor first. I'm sure my mistake here must be very simple, yet doing quite a lot of reading online hasn't led me to an answer.
Thanks for any information!
If you want to use functions defined in a particular file in Python you need to "import" that file first. This is similar to running the code in that file. Matlab doesn't require you to do this because it searches for files with a matching name and automagically reads in the code for you.
For example,
myFunction.py is a file containing
def myAdd(a, b):
return a + b
In order to access this function from the Python command line or another file I would type
from myFunction import myAdd
And then during this session I can type
myAdd(1, 2)
There are a couple of ways of using import, see here.
You need to a check for __main__ to your python script
def myFunction():
pass
if __name__ == "__main__":
myFunction()
then you can run your script from terminal like this
python myscript.py
Also if your function is in another file you need to import it
from myFunctions import myFunction
myFunction()
Python doesn't have MATLAB's "one function per file" limitation. You can have as many functions as you want in a given file, and all of them can be accessed from the command line or from other functions.
Python also doesn't follow MATLAB's practice of always automatically making every function it can find usable all the time, which tends to lead to function name collisions (two functions with the same name).
Instead, Python uses the concept of a "module". A module is just a file (your .py file). That file can have zero or more functions, zero or more variables, and zero or more classes. When you want to use something from that file, you just import it.
So say you have a file 'mystuff.py':
X = 1
Y = 2
def myfunc1(a, b):
do_something
def myfunc2(c, d):
do_something
And you want to use it, you can just type import mystuff. You can then access any of the variables or functions in mystuff. To call myfunc2, you can just do mystuff.myfunc2(z, w).
What basically happens is that when you type import mystuff, it just executes the code in the file, and makes all the variables that result available from mystuff.<varname>, where <varname> is the name of the variable. Unlike in MATLAB, Python functions are treated like any other variable, so they can be accessed just like any other variable. The same is true with classes.
There are other ways to import, too, such as from mystuff import myfunc.
You run python programs by running them with
python program.py
Is it possible to run code line by line with Python.
Including running any module code, when used, line by line as well.
I would like to go out and run some code line by line and watch as each of the lines goes through the processing phase and see just what code is getting executed when certain actions occur. I'm curious how certain values are getting passed off to the interpreter.
Just use python -m pdb mycode.py, which will run your code in the python debugger (pdb module).
In the debugger you can execute arbitrary code, watch variables, and jump to different places in the code. Specifically, n will execute the next line and h will show you the debugger help.
To add a breakpoint you can use pdb inline:
import pdb; pdb.set_trace()
From this line bleow you can go step by step and you can enter inside every called function (with s) or jump function execution (with n).
Also, a good tip is to use ipdb instead of pdb because it knows autocomplete (it's an ipython prompt)
when generating python wrappers with swig the python wrapper classes in the generated python file do not have an explicit self parameter, for example see below:
class PySwigIterator(_object):
def value(*args): return _spatiotemporalnmf.PySwigIterator_value(*args)
def incr(*args): return _spatiotemporalnmf.PySwigIterator_incr(*args)
def decr(*args): return _spatiotemporalnmf.PySwigIterator_decr(*args)
def distance(*args): return _spatiotemporalnmf.PySwigIterator_distance(*args)
I am developing with the eclipse pluging Pydev. Pydev always shows an error when it detects a method without explicit self parameter. I am aware of two methods to get rid of the errors: First, disable error checking for the whole project in the Pydev preferences. Second, add a ##NoSelf to every line with an error. I don't want to use the first one, because I still want to get error warnings for my non-swig-generated files. Obviously the second one is also not very good, because I would have to do it by hand and every time I generate the file again, all ##NoSelfs will be gone.
My Question now is, is there a better way to achieve this?
Thanks
As from the documentation, any file with the comment
##PydevCodeAnalysisIgnore
inside will not be analyzed.
Therefore, you just need to add it to all SWIG-generated files, and you should be OK. It is just one place to change, and you could even write a very small processor that will add it automatically.