I would like to identify what I call "periods" of data stocked in a pandas dataframe.
Let’s say i have these values:
values
1 0
2 8
3 1
4 0
5 5
6 6
7 4
8 7
9 0
10 2
11 9
12 1
13 0
I would like to identify sequences of strictly positive numbers with length superior or equal to 3 numbers. Each non strictly positive numbers would end an ongoing sequence.
This would give :
values period
1 0 None
2 8 None
3 1 None
4 0 None
5 5 1
6 6 1
7 4 1
8 7 1
9 0 None
10 2 2
11 9 2
12 1 2
13 0 None
>Solution :
You can try
sign = np.sign(df['values'])
m = sign.ne(sign.shift()).cumsum() # continuous same value group
df['period'] = (df[sign.eq(1)] # Exclude non-positive numbers
.groupby(m)
['values'].filter(lambda col: len(col) >= 3)
.groupby(m)
.ngroup() + 1
)
print(df)
values period
1 0 NaN
2 8 NaN
3 1 NaN
4 0 NaN
5 5 1.0
6 6 1.0
7 4 1.0
8 7 1.0
9 0 NaN
10 2 2.0
11 9 2.0
12 1 2.0
13 0 NaN