How to pass list from one function to another without using global variable?

Question

I am quite new to python and currently trying to work on a project that asks the user to read data from a csv file, and to store that data so that other functions can be performed on it. The only issue I seem to be having at the moment is that I can't use global variables.

Just now I have the following code structure:

import csv
import sys
data_set = []

def loadFile(x):
    with open(x, "r") as readfile:
        csv_reader = csv.reader(readfile, delimiter= ';')
        for row in csv_reader:
            data_set.append(row)
    print("Loaded weather data from", (x[0:-4]).capitalize())
    print()

def avgDay(x):
    for line in data_set:
        if(len(x) == 5 and (x[3:5] + "-" + x[0:2]) in line[0]):
           print("The weather on", x, "was on average", line[2], "centigrade")

Is there some way I can call data_set to other functions? (I have a few more functions that need to work with the data).

Answer 1

Yes, simply pass it in as a parameter, and return it when it is originally generated.

import csv
import sys

def loadFile(x):
    date_set = []
    with open(x, "r") as readfile:
        csv_reader = csv.reader(readfile, delimiter= ';')
        for row in csv_reader:
            data_set.append(row)
    print("Loaded weather data from", (x[0:-4]).capitalize())
    print()
    return data_set

def avgDay(x, data_set):
    for line in data_set:
        if(len(x) == 5 and (x[3:5] + "-" + x[0:2]) in line[0]):
           print("The weather on", x, "was on average", line[2], "centigrade")

def main():
    data_set = loadFile(...)
    avgDay(..., data_set)

if __name__ == 'main':
    main()