The Python Oracle

Find column whose name contains a specific string

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Chapters
00:00 Question
00:41 Accepted answer (Score 393)
01:51 Answer 2 (Score 134)
02:21 Answer 3 (Score 45)
02:50 Answer 4 (Score 34)
03:08 Thank you

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Full question
https://stackoverflow.com/questions/2128...

Accepted answer links:
[list comprehension]: http://docs.python.org/2/tutorial/datast...

Answer 2 links:
[This answer]: https://stackoverflow.com/a/20903553

Answer 3 links:
[pandas.Series.str.contains]: https://pandas.pydata.org/pandas-docs/st...

Answer 4 links:
[pandas.DataFrame.filter]: https://pandas.pydata.org/pandas-docs/st...

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Content licensed under CC BY-SA
https://meta.stackexchange.com/help/lice...

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Tags
#python #python3x #string #pandas #dataframe

#avk47



ACCEPTED ANSWER

Score 418


Just iterate over DataFrame.columns, now this is an example in which you will end up with a list of column names that match:

import pandas as pd

data = {'spike-2': [1,2,3], 'hey spke': [4,5,6], 'spiked-in': [7,8,9], 'no': [10,11,12]}
df = pd.DataFrame(data)

spike_cols = [col for col in df.columns if 'spike' in col]
print(list(df.columns))
print(spike_cols)

Output:

['hey spke', 'no', 'spike-2', 'spiked-in']
['spike-2', 'spiked-in']

Explanation:

  1. df.columns returns a list of column names
  2. [col for col in df.columns if 'spike' in col] iterates over the list df.columns with the variable col and adds it to the resulting list if col contains 'spike'. This syntax is list comprehension.

If you only want the resulting data set with the columns that match you can do this:

df2 = df.filter(regex='spike')
print(df2)

Output:

   spike-2  spiked-in
0        1          7
1        2          8
2        3          9



ANSWER 2

Score 146


This answer uses the DataFrame.filter method to do this without list comprehension:

import pandas as pd

data = {'spike-2': [1,2,3], 'hey spke': [4,5,6]}
df = pd.DataFrame(data)

print(df.filter(like='spike').columns)

Will output just 'spike-2'. You can also use regex, as some people suggested in comments above:

print(df.filter(regex='spike|spke').columns)

Will output both columns: ['spike-2', 'hey spke']




ANSWER 3

Score 49


You can also use df.columns[df.columns.str.contains(pat = 'spike')]

data = {'spike-2': [1,2,3], 'hey spke': [4,5,6], 'spiked-in': [7,8,9], 'no': [10,11,12]}
df = pd.DataFrame(data)

colNames = df.columns[df.columns.str.contains(pat = 'spike')] 

print(colNames)

This will output the column names: 'spike-2', 'spiked-in'

More about pandas.Series.str.contains.




ANSWER 4

Score 43


# select columns containing 'spike'
df.filter(like='spike', axis=1)

You can also select by name, regular expression. Refer to: pandas.DataFrame.filter