sorting DataFrame by columns using python

Question

Suppose I have a dataframe

df =
| CHROM | 
| ------| 
| chr1  | 
| chr5  |
| chr12 |
| chr9  |
| chr3  |

I have used this code to sort them:

sorted_df = df.sort_values(by=["CHROM"])

I got the result,

| CHROM | 
| ------| 
| chr1  | 
| chr12 |
| chr3  |
| chr5  |
| chr9  |

But, My expected output

| CHROM | 
| ------| 
| chr1  | 
| chr3  |
| chr5  |
| chr9  |
| chr12 |

Please suggest how to do using python

Mahdi F. · Accepted Answer · 2022-12-15 18:31:54Z

2

You can split base "chr" then sort the base number as int and find the index and return df with the sorted index.

idx = df["CHROM"].str.split('chr').str[-1].astype(int).sort_values().index
df_new = df.iloc[idx]
print(df_new)

df.sort_values(by=['CHROM'], 
               key=lambda x: df['CHROM'].str.split('chr').str[-1].astype(int))

Output:

   CHROM
0   chr1
4   chr3
1   chr5
3   chr9
2  chr12

answered Dec 15, 2022 at 18:22

Mahdi F.

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