Do what np.select(condlist, choicelist) does but instead with pandas only

Question

I have code and it works fine:

import numpy as np
import pandas as pd


x = np.arange(10)
condlist = [x<3, x==5, x>5]
choicelist = [x, x**2, x**3]
a=np.select(condlist, choicelist)

Now lets add:

y=pd.Series(x)

Lets now use y instead of x. Now we need to get same result (same content as a has, and it should be Series.) with pandas only, and the conditions and choices should be coded as above (use above code for coding conditions and choices). How to do that?

Expected output should be exactly same as code above gives in `a`. Data is in `y`. — vasili111, Apr 08 '20 at 01:14
Does this answer your question? [pandas equivalent of np.where](https://stackoverflow.com/questions/38579532/pandas-equivalent-of-np-where) — AMC, Apr 08 '20 at 01:41
@AMC I have done research. That this is useful but it did not answers question. Answer below solves the problem. — vasili111, Apr 08 '20 at 01:45
Isn't the top answer to that question the same solution as the answer to this one? — AMC, Apr 08 '20 at 01:45

Andy L. · Accepted Answer · 2020-04-08T01:38:59.577

construct a dataframe from choicelist and use df.where with condlist

s = pd.DataFrame(choicelist).where(condlist).ffill().fillna(0).iloc[-1]

Out[99]:
0      0.0
1      1.0
2      2.0
3      0.0
4      0.0
5     25.0
6    216.0
7    343.0
8    512.0
9    729.0
Name: 2, dtype: float64

If conditions are not overlapped, you may also use sum

s = pd.DataFrame(choicelist).where(condlist,0).sum()

Out[114]:
0      0
1      1
2      2
3      0
4      0
5     25
6    216
7    343
8    512
9    729
dtype: int64

Do what np.select(condlist, choicelist) does but instead with pandas only

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