python - How to find the average of values in a .txt file

Question

I need to find the minimum, maximum, and average of values given in a .txt file. I've been able to find the minimum and maximum values but I'm struggling with finding the average of values. I haven't wrote any coding for determining the average as I have no clue where to start. My current code is:

def summaryStats():
    filename = input("Enter a file name: ")
    file = open(filename)
    data = file.readlines()
    data = data[0:]
    print("The minimum value is " + min(data))
    print("The maximum value is " + max(data))

I need to be able to return the average of these values. As of now the .txt document has the following values:

893
255
504

I'm struggling on being able to find the average of these because every way I try to find the sum my result is 0.

Thanks (sorry I'm just learning to work with files)

Answer 1

You should convert the data retrived from file to integers first, because your data list contains strings not numbers. And after the conversion to integers average can be found easily:

Why conversion to int is required?

>>> '2' > '10'  #strings are compared lexicographically
True

Code:

def summaryStats():
    filename = input("Enter a file name: ")
    with open(filename) as f:
        data = [int(line) for line in f]

    print("The minimum value is ", min(data))
    print("The maximum value is ", max(data))
    print("The average value is ", sum(data)/len(data))

Output:

Enter a file name: abc1
The minimum value is  255
The maximum value is  893
The average value is  550.6666666666666