Write row to new csv if row[index] == "String" python

Question

Hi i'm trying to pass all rows which has index 7 = "Danmark" to another file. From a CSV file, i get the error "IndexError: list index out of range". Hope you guys can help me out.

import csv #import the module csv
with open('akassedatareduced.csv', encoding="ISO-8859-1") as csvfile, open('nydata.csv', 'w') as output:
    rowreader = csv.reader(csvfile) 
    fieldnames = ['CHURN/LOYAL', 'Medlemstype', 'Alder', 'Kon', 'Kommune', 'Uddannelsesnavn', 'Uddannelsessted', 'Land', 'Ledighed Historik', 'Telefon', 'Mobil', 'SamtaleType', 'Samtalested', 'Samtale maned', 'Churn maned', 'Dagpengeret maned', 'indmeldeses maned', 'fodselsdags maned']
    writer = csv.DictWriter(output,delimiter= ',',fieldnames=fieldnames)

#writer= csv.DictWriter.writeheader(fieldnames)
for row in rowreader:
    print(row[7])
    if row[7] == "Danmark":
        writer.writerow(row)

This is because some rows do not have an 8th column (remember that array numbering starts from 0). Please confirm if all rows have the 8th column. A better approach would be to use DictReader (docs.python.org/2/library/csv.html#csv.DictReader) and then access the column like row['ColumnName'] == 'Danmark'. — Roopak A Nelliat
– Roopak A Nelliat, Commented Oct 29, 2018 at 10:48

jpp · Accepted Answer · 2018-10-29 10:19:26Z

2

It looks like you have a malformed row. To debug this for yourself, use a try / except clause to catch IndexError:

for row in rowreader:
    try:
        if row[7] == "Danmark":
            writer.writerow(row)
    except IndexError:
        print(row)

Then, either let the errors pass silently, or fix your underlying data and rerun.

answered Oct 29, 2018 at 10:19

jpp

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Comments

Roopak A Nelliat · Accepted Answer · 2018-10-29 10:53:30Z

0

I would prefer using csv.DictReader. DictReader converts every row into a dictionary. This helps a lot as the script would still work even if the column order is changed, or any column is inserted/removed in between.

Your code will look like this when you use DictReader.

import csv #import the module csv
with open('akassedatareduced.csv', encoding="ISO-8859-1") as csvfile, open('nydata.csv', 'w') as output:
    rowreader = csv.DictReader(csvfile) 
    fieldnames = ['CHURN/LOYAL', 'Medlemstype', 'Alder', 'Kon', 'Kommune', 'Uddannelsesnavn', 'Uddannelsessted', 'Land', 'Ledighed Historik', 'Telefon', 'Mobil', 'SamtaleType', 'Samtalested', 'Samtale maned', 'Churn maned', 'Dagpengeret maned', 'indmeldeses maned', 'fodselsdags maned']
    writer = csv.DictWriter(output,delimiter= ',',fieldnames=fieldnames)

#writer= csv.DictWriter.writeheader(fieldnames)
for row in rowreader:
    print(row["Land"]) # Access using column name
    if row["Land"] == "Danmark":  # Access using column name
        writer.writerow(row)

answered Oct 29, 2018 at 10:53

Roopak A Nelliat

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3 Comments

Anders Over a year ago

Thanks helps me a bit further, i get no errors and it looks at the right column through the rows. However, the printed output says "none" and loops through all the rows with "Danmark".for row in rowreader: try: print(row["Land"]) # Access using column name if row["Land"] == "Danmark": writer.writerow(row) except IndexError: print(row)`

Roopak A Nelliat Over a year ago

Try printing row with print row and post the output.

Anders Over a year ago

This is the output when printing the print(row) Values are none OrderedDict([('CHURN/LOYAL', 'CHURN,Betalende,63,M,Gladsaxe Kommune,cand.polyt,Ikke pa liste,Danmark,Ingen Ledighedshistorik,Udfyldt,Ikke udfyldt,,,,"December, 1989","September, 1950","March, 1977","January, 1926"'), ('Medlemstype', None), ('Alder', None), ('Kon', None), ('Kommune', None), ('Uddannelsesnavn', None), ('Uddannelsessted', None), ('Land', None), ('Ledighed Historik', None), ('Telefon udfyldt status', None), ('Mobil udfyldt status', None), ('Samtaletype', None), ('Samtalested', None), ('Samtale Maned', None)

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