Python only writing first line of file?

Question

I previously posted a question iregards to a program organizing information in a file: Is there a way to organize file content by list element in python?

I am now trying to write the information to a new file using the following code

def main():
    #open the file
    info = open('Studentinfo.txt', 'r')
    #make file content into a list
    allItems = []
    #loop to strip and split
    for i in info:
        data = i.rstrip('\n').split(',')
        allItems.append(data)

    allItems.sort(key=lambda x: x[3]) # sort by activity

    for data in allItems:
        first = data[1]
        last = data[0]
        house = data[2]
        activity = data[3]
        a = str(first)
        b = str(last)
        c = str(house)
        d = str(activity)
    f = open('activites.txt', 'w')
    f.write(a)
    f.write(b)
    f.write(c)
    f.write(d)
    f.close()

main()

however when i open the new text file instead of

Amewolo, bob J.,E2,none
Andrade, Danny R.,E2,SOCCER
Banks-Audu, Rob A.,E2,FOOTBALL
Anderson, billy D.,E1,basketball
souza, Ian L.,E1,ECO CLUB
Garcia, Yellow,E1,NONE
Brads, Kev J.,N1,BAND
Glasper, Larry L.,N1,CHOIR
Dimijian, Annie A.,S2,SPEECH AND DEBATE

there is only

 Amewolo, bob J.,E2,none

why does python only write the first line

Answer 1

You are only writing to the file after the for loop instead of writing each set of data out one at a time. In other words, you're iterating over all the data, then after thate, you open the file, write the last 4 items, and then close it.

You need to open the file, write everything to it, and then close. Try this

f = open('activites.txt', 'w') # open the file first
for data in allItems: # iterate over all of the data
    first = data[1]
    last = data[0]
    house = data[2]
    activity = data[3]
    a = str(first)
    b = str(last)
    c = str(house)
    d = str(activity)
    f.write(a) # write each element out
    f.write(b)
    f.write(c)
    f.write(d)
f.close() # then close

However, the str() calls are unnecessary. first , last , house , and activity will already be strings.

combining with the with statement, this whole thing could collapse to

with open('activites.txt', 'w') as f:
    for data in allItems:
        data = [data[0], data[1]] + data[2:]
        print(*data, file=f, sep=', ')