Write a CSV in Multiple rows - Python 2.7

Question

I’m working on a csv file containing data recorders of game players. sample of csv shows 4 players (10 rows) and 13 columns:

Player_ID,Name,Age,DOB,Gender,Game1_result,Date_first_game,Game2_result,`Game3_result,Final_result,Team,Date_last_game,Finals_dates`
101,Ethan,16,1/15/2000,Male,won,3/20/2013,lost,won,lost,yellow,3/20/2013,3/20/2013
101,Ethan,16,1/16/2000,Male,won,12/6/2015,won,won,"won, full",yellow,12/6/2015,12/6/2015
101,Ethan,16,1/17/2000,Male,lost,1/6/2016,won,won,lost,yellow,1/6/2016,1/6/2016
102,Emma,19,6/17/1997,Female,won,1/9/2013,lost,lost,lost,green,1/9/2013,1/9/2013
...........
...........

I create a python script that converts dates to ages and then output the altered file. I use csv reader and writer to read and write the final output file (csv writes from a single list to which all data is appended). The final file should only include 12 columns (name not written) and all date columns converted to ages of players at that specific date.

import csv

##open data containing file

file1=open('example.csv','rb')
reader=csv.reader(file1)
####code to print headers
####age_converter() definition 

final_output=[]
for col in reader:
    final_output.append(col[0])#appends Player_ID
    final_output.append(col[2])#appends Age
    final_output.append(age_converter(col[3]))#appends value of date converted to age
    for r in range(4,6):
        final_output.append(col[r])#appends gender and game1 results
    final_output.append(age_converter(col[6]))#appends date of first game
    for r in range(7,11):
        final_output.append(col[r])#appends game results (5 columns)
    for r in range(11,13):
        final_output.append(age_converter(col[r]))#appends last and final dates

with open('output.csv','wb')as outfile:
    csv_writer=csv.writer(outfile)
    csv_writer.writerow(header)
    csv_writer.writerow(final_output)


file1.close()
outfile.close()

Age converter works fine, however, the output file has all data in one row. I tried to append columns one by one into a list and write it into csv, which works, but it is not practical to type each one of the columns by its index, especially that the original file I am working on has more than 50 columns! So my question is: How to write data into multiple rows instead of only one?

output sample:

Player_ID,Age,DOB,Gender,Game1_result,Date_first_game,Game2_result,Game3_result,Final_result,Team,Date_last_game,Finals_dates
101,17,Male,won,20,lost,won,lost,yellow,20,20,101,16,16,Male,won,19,won,won,"won, full",yellow,.....................

Doron Cohen · Accepted Answer · 2016-08-09 14:57:40Z

0

You are appending all the data to final_output. Instead, make it list of lists as so:

for row in reader:
    new_row = []
    new_row.append(row[0])
    ...
    final_output.append(new_row)

And then when writing to file:

csv_writer.writerow(headers)
for row in final_output:
    csv_writer.writerow(row)

Two notes:

Always use with open(...) as somefile. when you do, you don't need to close the file.
Checkout csv DictReader class for easier manipulating.

edited Aug 9, 2016 at 14:57

answered Aug 9, 2016 at 14:32

Doron Cohen

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5 Comments

joe_92 Over a year ago

it works but not correctly. same data is repeated for all rows

Doron Cohen Over a year ago

What data? Is every line the same length?

joe_92 Over a year ago

yes every line is the same lenght. each line (row) consists now of all players information, and that line is repeated 10 times.

Doron Cohen Over a year ago

I foxed a typo on the first code block line 3. Wrote col instead of row. See if you got it right.

joe_92 Over a year ago

It works! so the solution is to append rows into list then append all into a final list making it a list of lists. Thank you very much!

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