How can I count frequency by data in dataframe? [duplicate]

Question

I have an issue with groupby in pandsa. My DF looks like below:

I need result like below:

time   ID
01-13  2
01-14  1
01-15  2

So basically I need to count frequency ID by data. I treid with this but I am not sure of result (df is huge). Any idea? Thanks for help

df = df.groupby("Time").Id.value_counts()

Best regards

johnjohn · Accepted Answer · 2021-03-12 09:29:52Z

2

One way is:

df.time.value_counts()

Output:

01-15    2
01-13    2
01-14    1
Name: time, dtype: int64

Other way, as suggested by reviewer above:

df.groupby(['time']).size().reset_index(name='Frequency')

Output:

    time    Frequency
0   01-13   2
1   01-14   1
2   01-15   2

Note you can group by several variables if needed:

df.groupby(['col1', 'col2', 'etc.'])...

answered Mar 12, 2021 at 9:13

johnjohn

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