How to split and rename columns at the same instance in pandas?

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I have a dataframe called thyroid_df.

>>> thyroid_df
                      0  1         2
0    chr1:233276815:A:G  A  0.277632
1    chr2:217427435:C:G  C  0.357674
2    chr3:169800667:T:G  T  0.207014
3      chr5:1279675:C:T  T  0.182322
4    chr5:112150207:A:T  A  0.314811
5     chr8:32575278:G:T  G  0.277632
6     chr9:97775520:A:C  A  0.524729
7   chr10:103934543:C:T  T  0.343590
8    chr14:36063370:G:C  G  0.329304
9    chr14:36269155:C:T  T  0.593327
10   chr15:67165147:G:C  C  0.207014
11   chr15:67163292:C:T  T  0.215111

I want to split the first column by : and rename the column names. I tried this below which doesn't seem to work. I want to rename column names with the same line of code.

thyroid_df[0].str.split(':', 3, expand=True).rename(columns = ["CHROM", "POS_GRCh38", "REF", "Effect_allele"])

python
2 Answers

This should work. Then you could drop columns 0 if you no longer need it.

df[["CHROM", "POS_GRCh38", "REF", "Effect_allele"]] = df[0].str.split(':', 3, expand=True)
user2uNj0

You can do:

new_cols = ["CHROM", "POS_GRCh38", "REF", "Effect_allele"]
thyroid_df[0].str.split(':',expand=True).rename(columns={i:new_cols[i] for i in range(4)})

output:

    CHROM POS_GRCh38 REF Effect_allele
0    chr1  233276815   A             G
1    chr2  217427435   C             G
2    chr3  169800667   T             G
3    chr5    1279675   C             T
4    chr5  112150207   A             T
5    chr8   32575278   G             T
6    chr9   97775520   A             C
7   chr10  103934543   C             T
8   chr14   36063370   G             C
9   chr14   36269155   C             T
10  chr15   67165147   G             C
11  chr15   67163292   C             T
SomeDude0
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