write csv in python based on sub-string condition

Question

I have the following result variable in a data frame (df) and I am trying to output a csv file for those that starts with "test"

abandoned
static
test_a_1
test_b_2
abandoned
test_b_3

The following code is not working. Thanks in advance for your insights

substr="test"
if substr in df['result']:
    df.to_csv("C:/Projects/result.csv",sep=',',index=False)

when you say not working do you mean it's not writing at all or writing the wrong thing? — depperm
– depperm, Commented Sep 29, 2016 at 15:48
Its not writing. The result of substr in df['result'] is false — Prasad
– Prasad, Commented Sep 29, 2016 at 15:51

Ben Quigley · Accepted Answer · 2016-09-29 15:51:49Z

3

Just because "test_a_1" is in the list does not mean that "test" is, in Python logic.

Example of how Python evaluates "if [string] in [list]" statements:

>>> test = 'test1'
>>> testlist = ['test1', 'test2']
>>> if 'test' in test:
...     print('hi')
... 
hi
>>> if 'test' in testlist:
...     print('hi')
... 
>>>

This would work:

substr="test"
for val in df['result']:
    if substr in val:
        # Do stuff
        # And optionally (if you only need one CSV per dataframe rather than one CSV per result):
        break

answered Sep 29, 2016 at 15:51

Ben Quigley

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2 Comments

Prasad Over a year ago

Thanks Iroh.. This gives the output for all the result values, but I am interested to see test_a_1,test_b_2,test_b_3 rows in csv.

Ben Quigley Over a year ago

Looks like scomes's solution works for that, plus it's a sexy one-liner. ;)

scomes · Accepted Answer · 2016-09-29 15:54:13Z

1

If what you mean is that you want to make a csv that only contains the rows for which result starta with 'test', use the following:

df[df.result.str.contains('^test.*')].to_csv("C:/Projects/result.csv",sep=',',index=False)

answered Sep 29, 2016 at 15:54

scomes

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Comments

MMF · Accepted Answer · 2016-09-29 15:56:29Z

0

This would work :

df['temp'] = [1 if 'test' in df['result'][k] for k in df.index else 0]
df['result'][df['temp']==1].to_csv("/your/path", sep=',', index=False)

answered Sep 29, 2016 at 15:56

MMF

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