"Chromosome" and "Strand" columns become "object" dtype instead of "category" after .merge_overlaps()

[jeanmonet]

Hi, I've found this dtype discrepancy before & after applying merge_overlaps():

gtfpr.remove_nonloc_columns().dtypes

Chromosome    category
Start            int64
End              int64
Strand        category
dtype: object

However Chromosome & Strand columns become of object dtype after merge_overlaps():

gtfpr.remove_nonloc_columns().merge_overlaps().dtypes

Chromosome    object
Start          int64
End            int64
Strand        object
dtype: object

Is this expected behavior or is it a bug?

---

In addition, using .join_ranges with join_type="left" produces dtypes of type float64 for Start_b, End_B and other columns, whereas join_type="inner" keeps those to their original int64 dtype:

joined = gtf_ext.join_ranges(fragments, join_type="left")

	Chromosome	Start	End	Start_b	End_b	barcode	count	ucount
0	chr1	55418	65419	56893.0	57061.0	CATGGATTCTTGCAGG-1	3.0	1.0
1	chr1	55418	65419	57033.0	57135.0	TTGTGCGAGTCATTTC-1	1.0	1.0


joined = gtf_ext.join_ranges(fragments, join_type="inner")


Chromosome	Start	End	Start_b	End_b	barcode	count	ucount
0	chr1	55418	65419	56893	57061	CATGGATTCTTGCAGG-1	3	1
1	chr1	55418	65419	64419	64681	CGCACACAGCGTGCGT-1	1	1

[endrebak]

Definitely not intended behavior. Will fix when I'm done with my PhD revision