如何根据 pandas 列中最后一次出现的字符串提取 dataframe 的子集？

Question

I have a dataframe lik below

ID	name	number
1	Sta	2
1	Danny	5
1	Sta	2
1	elle	4
1	Sta	2
1	jake	9
1	Andy	11
1	Adam	22
1	blah	44
1	blahblah	66

I want to extract the records till the last occurrence of Sta. like this below

ID	name	number
1	Sta	2
1	Danny	5
1	Sta	2
1	elle	4
1	Sta	2

I am not sure how I can do that. Can someone please suggest?

Answer 1

 first, *_, last = df.index[df.name.eq('Sta')]
df.loc[first:last]

   ID   name  number
0   1    Sta       2
1   1  Danny       5
2   1    Sta       2
3   1   elle       4
4   1    Sta       2

Get the first and last labels for Sta and index df

Answer 2

I would find Sta 's last occurrence and use it as the slicing parameter. There's an interesting function I didn't know that I found out working out this answer, last_valid_index() might be really helpful here.

filtered = df.loc[:df[df['name']=='Sta'].last_valid_index(),:]

Answer 3

staRows = df.loc[df.name == "Sta", :]
lastStA = staRows.tail()
lastStaLoc = df.index[lastSta]
final = df.loc[0:lastStaLoc]

altFinal = df.loc[0:df.index[df.loc[df.name == "Sta", :].tail()]]

staRows is every row where name is Sta

lastSta is the last row in staRows

lastStaLoc is the location of lastSta

final should be rows up to lastStaLoc

altFinal is the one line solution if you want to be fancy. This is all untested so you may have to debug a bit:)

Answer 4

Let us do groupby with transform idxmax

df[df.index<=df['name'].eq('Sta').iloc[::-1].groupby(df['ID']).transform('idxmax')]
   ID   name  number
0   1    Sta       2
1   1  Danny       5
2   1    Sta       2
3   1   elle       4
4   1    Sta       2