Parsing a CSV row into columns with the first entry in each row as the first entry in each column

Question

I have a csv file that I need to change so that I can create an input file. The data is set up so that it's keyname, and then data such as:

allendata,test@test.com,test1@test.com  
allendata2,test1@test.com,test@test.com,test3@test.com

I need the output formatted so that I end up with

allendata,test@test.com
allendata,test1@test.com
allendata2,test1@test.com
allendata2,test@test.com
allendata3,test3@test.com

There are about 1800 lines like this, so I'll end up with somewhere around 30000 lines when it's all parsed out.

I'll take any method possible, with bash or python being preferable.

Thanks, Allen

Answer 1

This should do the trick

fIn = open('testIn.txt', 'r')
fOut = open('testOut.txt','w')

for line in fIn:
    data = line.split(',')
    name = data[0]
    for address in data[1:]:
        fOut.write(name + ',' + address + '\n')

fIn.close()
fOut.close()

'textIn.txt'

allendata,test@test.com,test1@test.com  
allendata2,test1@test.com,test@test.com,test3@test.com

'testOut.txt'

allendata,test@test.com
allendata,test1@test.com    
allendata2,test1@test.com
allendata2,test@test.com
allendata2,test3@test.com

Answer 2

You could do it using awk like this:

$ awk -F, '{for(i=2;i<=NF;i++) print $1","$i}' file > new_file
$ cat new_file
allendata,test@test.com
allendata,test1@test.com  
allendata2,test1@test.com
allendata2,test@test.com
allendata2,test3@test.com