Python - Extract private variables from a function?

Question

I have a function f2(a, b)

It is only ever called by a minimize algorithm which iterates the function for different values of a and b each time. I would like to store these iterations in excel for plotting.

Is it possible to extract these values (i only need to paste them all into excel or a text file) easily? Conventional return and print won't work within f2. Is there any way to extract the values a and b to a public list in the main body some other way?

The algorithm may iterate dozens or hundreds of times.

So far I have tried:

• Print to console (can't paste this data into excel easily)

• Write to file (csv) within f2, the csv file gets overwritten within the function each time though.

Answer 1

Append the values to a global list.

values = []
def f2(a,b):
    values.append((a,b))
    #todo: actual function logic goes here

Then you can look at values in the main scope once you're done iterating.

Answer 2

Write to file (csv) within f2, the csv file gets overwritten within the function each time though.

Not if you open the file in append mode:

with open("file.csv", "a") as myfile: