Passing values between modules in Python

Question

I want to know how to pass values between modules in Python.

In generate_image.py I have:

def gerenate_image(fr,to,lat1,lon1,lat2,lon2):
 output_image_name = spatial_matrix.plot_spatial_data(data_array,data_array.shape[0],data_array.shape[1],float(lon1)/10000,float(lon2)/10000,float(lat1)/10000,float(lat2)/10000,fr,to)
return()

In overlay.py, I want to use the "output_image_name",so I tried:

import generate_image
def overlay():
 overlay = generate_image.output_image_name
 ....

but it didn't work. So how can I retrieve the value of output_image_name?Thanks.

• Martijn Pieters: This is one of those situations where I recommend you read the Python tutorial from cover to cover.

Answer 1

Make your function return something.

def generate_image(fr,to,lat1,lon1,lat2,lon2):
 return spatial_matrix.plot_spatial_data(data_array,data_array.shape[0],data_array.shape[1],float(lon1)/10000,float(lon2)/10000,float(lat1)/10000,float(lat2)/10000,fr,to)

Then in the other place import and call the function.

from yourmodule import generate_image
def overlay():
 background = generate_image(*args) # Or what ever arguments you want.

• oops: Thank you for your answer! but the problem now is that the args in generate_image involves a lots of other modules and I have to import them all..is there an easier way to pass the value of "output_image_name" in gerenate_image.py?

Answer 2

In overlay.py:

def gerenate_image(fr,to,lat1,lon1,lat2,lon2):
 return spatial_matrix.plot_spatial_data(...)

In generate_image.py:

import generate_image
def overlay():
 overlay = generate_image.generate_image(...)

• Jakob Bowyer: Yes that and on overlay = generate_image.generate_image() where it expects 6 arguments and you give it none.
• Otto Allmendinger: That wouldn't be a syntax error. I've shortened the code to get the main point across.
• Jakob Bowyer: But people that didn't know that would try to run it, get a syntax error
• Otto Allmendinger: Calling a function with the wrong number of arguments is a TypeError