Probability of re occurring an event

Question

I have a dataframe like below:

ItemNumber ItemName 
264         400
264         420
264         400
264         420
264         420
513         508
513         508
513         400
513         400
513         126
513         126

here i would like to see frequency of particular ItemName. and probability of reoccurring an ItemName with respect to ItemNumber.

I have tried using groupby function but I'm not getting the desired format using approach below:

import numpy as np
import pandas as pd

ByItemName = df.groupby(['ItemName'])

My desired output:

ItemNumber ItemName ItemNameFrequency
264        400      2
264        420      3
513        508      2
513        400      2
513        126      2

Check second answer - [this](https://stackoverflow.com/a/32801170/2901002) — jezrael, Apr 01 '19 at 12:46
@DirtyBit please don't make such unsubstantial edits to the posts as the one here, you are only creating more noise without any improvement. — Szymon Maszke, Apr 01 '19 at 12:48
@SzymonMaszke It wasn't an unsubstantial edit, I was halfway through and I guess you approved it. anyway no worries! (Y) — DirtyBit, Apr 01 '19 at 12:53

DirtyBit · Accepted Answer · 2019-04-01T12:51:51.990

1

Perhaps:

import pandas as pd
df = pd.DataFrame({'ItemNumber' : ['264', '264', '264', '264','264','513','513','513','513', '513','513'], 'ItemName' : ['400','420','400','420','420','508','508','400','400', '126','126']})
df = df.groupby(['ItemNumber', 'ItemName']).size().reset_index(name = 'ItemNameFrequency')
print(df)

OUTPUT:

  ItemNumber ItemName  ItemNameFrequency
0        264      400                  2
1        264      420                  3
2        513      126                  2
3        513      400                  2
4        513      508                  2

edited Apr 01 '19 at 12:51

answered Apr 01 '19 at 12:37

DirtyBit

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@jezrael Indeed, omitted the series part, thank you! – DirtyBit Apr 01 '19 at 12:52

Probability of re occurring an event

1 Answers1