CODEWITHSUNDEEP
pandas
Binu
Binu

Reputation: 153

Pandas Dataframe Checking Consecutive Values in a colum

Have a Pandas Dataframe like below.

EventOccurrence Month
1                4
1                5
1                6
1                9
1                10
1                12

Need to add a identifier column to above panda's dataframe such that whenever Month is consecutive thrice a value of True is filled, else false. Explored few options like shift and window without luck. Any pointer is appreciated. 

EventOccurrence Month Flag
1               4       F  
1               5       F
1               6       T
1               9       F
1               10      F
1               12      F

Thank You.

Upvotes: 1

Views: 43

Answers (1)

sacuL
sacuL

Reputation: 51335

You can check whether the diff between rows is one, and the diff shifted by 1 is one as well:

df['Flag'] = (df.Month.diff() == 1) & (df.Month.diff().shift() == 1)

   EventOccurrence  Month   Flag
0                1      4  False
1                1      5  False
2                1      6   True
3                1      9  False
4                1     10  False
5                1     12  False

Note that this will also return True if it is consecutive > 3 times, but that behaviour wasn't specified in the question so I'll assume it's OK

If it needs to only flag the third one, and not for example the fourth consecutive instance, you could add a condition:

df['Flag'] = (df.Month.diff() == 1) & (df.Month.diff().shift() == 1) & (df.Month.diff().shift(2) !=1)

Upvotes: 1

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