Remove row if the last one is equal

Question

I have this dataframe in Pandas

date	value
2023-01	0
2023-02	0
2023-03	-1
2023-04	-1
2023-05	0
2023-06	0
2023-07	-1
2023-08	-1

I would like to transform it to:

date	value
2023-01	0
2023-03	-1
2023-05	0
2023-07	-1

what happens if more than 2 of same value. remove all except first or remove only last? if keep only first maybe `df[df['value'] != df['value'].shift(1)]` — cmgchess, Aug 31 '23 at 04:32

score 1 · Answer 1 · answered Aug 31 '23 at 04:40

Use boolean indexing with shift:

out = df[df['value'].ne(df['value'].shift())]

Output:

      date  value
0  2023-01      0
2  2023-03     -1
4  2023-05      0
6  2023-07     -1

Intermediates:

      date  value  value_shift     ne
0  2023-01      0          NaN   True
1  2023-02      0          0.0  False
2  2023-03     -1          0.0   True
3  2023-04     -1         -1.0  False
4  2023-05      0         -1.0   True
5  2023-06      0          0.0  False
6  2023-07     -1          0.0   True
7  2023-08     -1         -1.0  False

Remove row if the last one is equal

1 Answers1