从熊猫数据框中选择符合条件的行

Question

I have two unequal pandas data frames df and df1. df looks like this:

Chr	Start	End	Freq
chr1	1	1000	0.05
chr2	4500	5780	0.0099
chr2	5700	6540	1.3

df1 looks like this:

Chr	Start-500	Start+500	End-500	End+500
chr1	-499	501	500	1500
chr2	4000	5000	5280	5280
chr2	5200	6200	6040	7040

What I want to do is if:
- df['chr']==df1['chr'] and
- df['Start] is in between df1['Start-500] and df1['Start+500'] and
- df['End'] is between df1['End-500'] and df1["End+500']
then add the Freq to df1 .

Please if any one can help me that would be great. Thank you

Answer 1

Since your "Start-500", "Start+500" is simply based on the "Start" column (and similarly for "End"), you can simply use pandas.merge_asof :

df1["Freq"] = pd.merge_asof(df1, df, left_on="Start+500", right_on="Start")["Freq"]

>>> df1
    Chr  Start-500  Start+500  End-500  End+500    Freq
0  chr1       -499        501      500     1500  0.0500
1  chr2       4000       5000     5280     5280  0.0099
2  chr2       5200       6200     6040     7040  1.3000