[BUG]

[GG-Delta]

datar version checks

• I have checked that this issue has not already been reported.

• I have confirmed this bug exists on the latest version of datar and its backends.

Issue Description

Hey pwwang,
My apologies that I couldn't figure out the root problem myself. When trying to reproduce one of your examples using the starwars dataset using the count function it doesn't show the counts (i.e. the n column) for each category (as demonstrated in your example: https://pwwang.github.io/datar/notebooks/count/). My code is the following:

# Import Python modules
import pandas as pd
import numpy as np
import janitor
from datar.data import starwars
from datar.all import *

# Code to reproduce datar example using count
starwars >> count(f.species)

This code leads to this outcome (missing the n column):

Expected Behavior

Expected behaviour: to generate the output with the count in a seperate column named n as shown in your tutorial example: https://pwwang.github.io/datar/notebooks/count/

Any hint how I could fix this would be highly appreciated! Many thanks in advance! All the best, Gernot

Installed Versions

datar 0.13.1 datar-numpy 0.2.1 datar-pandas 0.3.1

---- Update
Hey pwwang! Thanks a lot for taking a look into this issue! The output of data.getversions() is as follows:
python : 3.10.5 (main, Oct 7 2022, 13:57:40) [Clang 14.0.0 (clang-1400.0.29.102)] datar : 0.13.1 simplug : 0.3.2 executing : 1.2.0 pipda : 0.12.0 datar-numpy : 0.2.1 numpy : 1.25.2 datar-pandas: 0.3.1 pandas : 2.0.3

Thanks again & Cheers, Gernot

[pwwang]

I can't reproduce this.

In [1]: # Import Python modules
   ...: import pandas as pd
   ...: import numpy as np
   ...: from datar.data import starwars
   ...: from datar.all import *

In [2]: starwars >> count(f.species)
Out[2]: 
           species       n
          <object> <int64>
0            Human      35
1            Droid       6
2          Wookiee       2
3           Rodian       1
4             Hutt       1
5   Yoda's species       1
6       Trandoshan       1
...

Can you provide the output of datar.get_versions()?

[GG-Delta]

Hey pwwang, Sure! Thanks a lot for taking a look into this issue! The output of data.getversions() is as follows:
python : 3.10.5 (main, Oct 7 2022, 13:57:40) [Clang 14.0.0 (clang-1400.0.29.102)] datar : 0.13.1 simplug : 0.3.2 executing : 1.2.0 pipda : 0.12.0 datar-numpy : 0.2.1 numpy : 1.25.2 datar-pandas: 0.3.1 pandas : 2.0.3

Thanks again & Cheers, Gernot

[pwwang]

The problem should be the version of pandas. datar-pandas only supports pandas 1.x. You have pandas 2.x installed.

pandas 2.x uses pyarrow as backend, while pandas 1.x uses numpy. They are different in a lot of ways. We need a separate backend to support pandas 2.

[GG-Delta]

Hey pwwang! Thanks a lot for checking! You are right! Indeed the issue is based on using a different pandas version. I just tested it with an older pandas version 1.5.3. And the datar count function worked as expected again - exactly as you suggested. I was not aware about the massive changes associated with pandas 2.x Unfortunately I need pandas 2.x for another functionality in this project... so it is a pity that I can't use datar in this context. Thank you again! All the best, Gernot