Question

How to do read a .csv file with the following content

$C=2$A=3$B=1$

Then create a new .csv file with the same content but the $ changed into , and sorted alphabetically like the following:

A=3,B=1,C=2

Thank you!

Edit:

Here’s my following code. It ended up giving an extra comma at the beginning of the output.

input = csv.reader(open('inputfile.csv','r'), delimiter='$')
output = open('outputfile.csv','w')
try:
    writer = csv.writer(output)
    for column in input:
        writer.writerow(sorted(column))
        print (sorted(column))
finally:
    out.close()

Right now my input is:

$C=2$A=3$B=1$

and my output is:

,A=3,B=1,C=2

I want it to be:

A=3,B=1,C=2

Thanks!

Answer 1

with open('test.csv') as in_file, open('new.csv', 'w') as out_file:
    for line in csv.reader(in_file, delimiter='$'):
        out_file.write(','.join(sorted(line)[2:])+'\n')

Basically what this does is:

• open the input as in_file
• open the output as out_file
• initializes a CSV reader with $ as the delimiter using in_file as the input file
• iterates through each row doing the following:
  • sort all of the elements (after parsing)
  • discard the first 2 (since they’ll always be empty strings due to the start/end delimiters on each line)
  • recombine those elements using , as the delimiter
  • write that out to the file with a trailing newline \n

edit: fixed for the start/end $ symbols by removing the empty elements that get parsed out of the CSV (the [2:] bit)