Pandas - Delete all consecutive rows except the first one which share same column value

Question

I have a Data-Frame like following:

A B C D
- - - -
h e l 0
t h i 0
i s m 0
q u e 1
s t i 1

I want to delete all the rows that have same value in D consecutively but leaving the first one. The result will be following:

A B C D
- - - - 
h e l 0
q u e 1

So, far I've done it using following code:

df[list(map(lambda x: (x == 0) or (df['D'][x] != df['D'][x-1]), range(len(D))))]

I'm wondering if there a better way to do this?

@jezrael this looks different than the one you marked duplicate against. The OP wants consecutive duplicates to be removed — Vivek Kalyanarangan, Nov 19 '18 at 13:06

score 4 · Accepted Answer · answered Nov 19 '18 at 13:04

4

Use -

df.loc[df['D'].shift(1) != df['D']]

Output

    A   B   C   D
0   h   e   l   0
3   q   u   e   1

answered Nov 19 '18 at 13:04

I fear this won't work if `0` occurs more than 2 times. Right? – Lokesh Nov 19 '18 at 13:06
@Lokesh didn't get you. I tried it against OP's example which contains 3 consecutive duplicates and it worked for me – Vivek Kalyanarangan Nov 19 '18 at 13:07
2

Thanks for the great answer. Working without a problem! You rock – Lokesh Nov 19 '18 at 13:14

1 Answers1