I'm very new to using canopy and programming in general.
I'm trying to define a function in Python in the canopy editor. This used to work for me but has suddenly stopped and I have no idea why.
As a basic example, in the editor I wrote;
def funct(x):
return x
When write funct(1) in the shell I get the error message
NameError: name 'funct' is not defined
Any ideas?
Thanks
You need to "run" your script (in the editor) before its results actually exist (and are visible in) the Python shell. In this case the results of your script are to define your function. Just writing the function in the editor doesn't actually create it in Python until you run the script.
As Ali correctly said, another (deeper) approach is to import the script (in this case known as a module), but I think running is probably more what you have in mind.
I've never used Canopy before, but in general you would save the file where your function is defined somewhere in your working directory (e.g. as myfunct.py), then import it into the shell namespace:
In [1]: import myfunct
In [2]: myfunct.funct(1)
Out [2]: 1
Related
I'm having trouble getting certain functions from a library called art (https://github.com/sepandhaghighi/art) to run in a script, though they work fine in a shell. The script/commands entered sequentially look like this:
from art import *
randart() <(function fails in script, but succeeds in shell)
tart("test") <(different function, same library, succeeds in both shell and script)
import sys
print(sys.version)
The python version is 3.7.5 for both the shell and the script. The first function does not throw an error when run in a script, but does not give any output. Its desired output is a random ascii_art from a collection. I feel like I'm missing something really simple. Any ideas? The documentation on github reports "Some environments don't support all 1-Line arts", however they are the same python version on the same machine. Are there other portions of the environment that could be the cause?
You need to print randart() while writing in script. Make a habit of using print() for everything while printing. Shell is the place which returns the value by default whereas you need to tell the script window what to do with any name or function.
so use this:
from art import *
print(randart())
in the shell it is implicitly printed ... in a script you must explicitly
print(randart())
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.
def c1(a1,b1):
a1=2
b1=3
cc=a1+b1
return cc
I have saved this function in test.py. When I use this function in MATLAB I encountered this problem:
import py.test.* c1(2,3)
Undefined function 'c1' for input arguments
of type 'double'.
py.test.c1(2,3)
Undefined variable "py" or class
"py.test.c1".
How can I use .py function in MATLAB R2014b？
If you get the error message below, a failure has occurred.
Undefined variable "py" or class
There are a lot of things that might be wrong here, and Mathworks have actually set up a whole tutorial for how to troubleshoot this problem. (The title of the page is actually: Undefined variable "py" or function "py.command", so it should contain most of what you need)
Check out the following:
Python Not Installed
64-bit/32-bit Versions of Python on Windows Platforms
MATLAB Cannot Find Python
Error in User-Defined Python Module
Python Module Not on Python Search Path
Module Name Conflicts
Python Tries to Execute command in Wrong Module
Starting from Matlab 2014b Python functions can be called directly - using prefix py, then module name, and finally function name like so:
result = py.module_name.function_name(parameter1);
However, one has to make sure to add the script to the Python search path when calling from Matlab (especially if the first time Python is called the current working directory is different than that of the Python script.
See more details here.
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
So let's say I have a script script1. Is there a way to interact with script1's variables and functions like an interpreter after or during its runtime?
I'm using IDLE and Python 2.7, but I'm wondering if I could do this in any interpreter not just IDLE's.
Say in my script, get = requests.get("example.com"). I'd like to hit F5 or whatever to run my script, and then instead of the console unloading all of the variables from memory, I'd like to be able to access the same get variable.
Is this possible?
That's a serious question. You might need to consult this page:
https://docs.python.org/2/using/cmdline.html#miscellaneous-options
Note the -i option, it makes interpreter enter interactive mode after executing given script.
you can do like this:
#file : foo.py
import requests
def req():
get = requests.get("example.com")
return get
and then run the script from a console
import foo
get = foo.req()