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nhatbui/count_unique.py

Last active November 20, 2015 05:55
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Count Unique from Pandas DataFrame
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count_unique.py
import pandas as pd
d = {
'a': ['1','1','2','2','2','3'],
'b': ['green', 'blue','yellow','yellow','blue','green']
}
df = pd.DataFrame.from_dict(d)
df_count = pd.crosstab(df['a'], df['b'])
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nhatbui commented Nov 20, 2015

Motivation: Is there a Pandas-only way to take a DataFrame, group by a column, and count all unique values of another column?

>>> df
   a       b
0  1   green
1  1    blue
2  2  yellow
3  2  yellow
4  2    blue
5  3   green
>>> df_count = some_process(df)
>>> df_count
   blue  green  yellow
1     1      1       0
2     1      0       2
3     0      1       0

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