Frequency of a single value in dataframe column

Question

Let a column of dataset be

ITEM
2
10
-200
3
6
-200
-200

and i want to get only the number of times -200 occured in the column and also the percentage
for example in given data set we have 7 rows and out of those, 3 rows have -200 then result should be 42.8%

I tried

df['ITEM'].value_counts()

where df is data frame
and i want result to be
-200 42.8%

Asked By: Gurneet

||

Source

Answer 1

You can try Series.value_counts with normalize=True then select the -200 row

out = (df['ITEM'].value_counts(normalize=True)
       .mul(100).round(1).astype(str).add('%')
       [[-200]])

$ print(out)

-200    42.9%
Name: ITEM, dtype: object

Answered By: Ynjxsjmh

Answer 2

import pandas as pd
df = pd.DataFrame(data={'a':[2,10,-200,3,6,-200,-200]})

print(df["a"].value_counts(normalize=True) * 100)
# -200    42.857143
#  2      14.285714
#  10     14.285714
#  3      14.285714
#  6      14.285714

Answered By: BERA

Frequency of a single value in dataframe column

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