Tukukkk

I have a csv file with rows of key pairs.

Let us call key, 'key' and the different values 'a', 'b', 'c', etc..

I am trying to use csv.writer so that it writes the row onto a file only if the value is 'b'.

I have the following code so far:

csvfileR = 



with open('csvfileR.csv', 'r') as csvfile:

    reader = csv.DictReader(csvfile)

    for row in reader:

        csvfileR.append(row)



w = open('csvfileW.csv','w')

fieldnames = ['key']

writer = csv.writer(w)

writer.writerow(fieldnames)



for i in range(len(csvfileR)):

    if csvfileR[i]['key'] == 'b':

        print (csvfileR[i]['key'])

        fields = [csvfileR[i]['key']]

        writer.writerow(fields)

The issue is that writer writes correctly when we filter for value 'a' (if csvfileR[i]['key'] == 'a') but gives a blank csv file when we filter for any other value (if csvfileR[i]['key'] == 'b' (or 'c' or 'd' etc)).

The print method works correctly for all values so the Dict is appended correctly.

Specifically, csvfileR contains data of my asset trades. I want csv.writer to create 'csvfileW' with trade data for only one asset in a series of different assets.

One row of csvfileR would look like:

OrderedDict([('Date', '2016.09.12'), ('Name of Asset Traded', 'Facebook Stock'), ('Price purchased', '$100'), ('Price sold, '$150')

The issue is that csv.writer will write if I filter out for my first asset 'Facebook Stock', but will not write if I filter out for any other asset.

So

if csvfileR[i]['Name of Asset Traded'] == 'Facebook Stock'

will create a CSV file correctly but,

if csvfileR[i]['Name of Asset Traded'] == 'Apple Stock'

or

if csvfileR[i]['Name of Asset Traded'] == 'FedEx Stock'

will create a blank CSV file.

However,

print (csvfileR[i]['Name of Asset Traded'])

will print out 'Apple' or ''FedEx' each time it runs into it.

As mentioned consider using one single with to handle read and write of both files and even avoid the need of the csvfileR list.

with open('csvfileR.csv', 'r') as csvfile, open('csvfileW.csv', 'w') as outfile:

    fieldnames = ['key']

    writer = csv.writer(outfile)

    writer.writerow(fieldnames)



    reader = csv.DictReader(csvfile)



    for row in reader:

        if row['key'] == 'b':

            print (row['key'])

            fields = [row['key']]

            writer.writerow(fields)

However, code above seems strange as only b would output in first column of output csv. Likely, post does not reflect actual code. Adjust above as needed.

Just figured it out. Very silly mistake. Did not include w.close() at the end of the code. Code works fine now. Thank you for your help.