Python Pandas:我怎样才能将一个id分配给一个组中的所有项目? [英] Python Pandas: How can I group by and assign an id to all the items in a group?
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问题描述
我有df:
域名orgid
csyunshu.com 108299
dshu.com 108299
bbbdshu.com 108299
cwakwakmrg.com 121303
ckonkatsunet.com 121303
我想添加一个新列,用每个orgid的数字id替换域列:
域orgid domainid
csyunshu.com 108299 1
dshu.com 108299 2
bbbdshu.com 108299 3
cwakwakmrg.com 121303 1
ckonkatsunet.com 121303 2
$ c
我已经尝试过这一行,但它并没有给出我想要的结果:
$ b df.groupby('orgid')。count ['domain']。reset_index()
任何人都可以帮忙吗?
解决方案您可以调用 code> groupby
对象并传入param method ='first'
:
<$ c $在[61]中:
df ['domainId'] = df.groupby('orgid')['orgid']。rank(method ='first')
df
出[61]:
域名orgid domainId
0 csyunshu.com 108299 1
1 dshu.com 108299 2
2 bbbdshu.com 108299 3
3 cwakwakmrg.com 121303 1
4 ckonkatsunet.com 121303 2
如果您想覆盖你可以这样做:
df ['domain'] = df.groupby('orgid')['orgid']。 rank(method ='first')
I have df:
domain orgid
csyunshu.com 108299
dshu.com 108299
bbbdshu.com 108299
cwakwakmrg.com 121303
ckonkatsunet.com 121303
I would like to add a new column with replaces domain column with numeric ids per orgid:
domain orgid domainid
csyunshu.com 108299 1
dshu.com 108299 2
bbbdshu.com 108299 3
cwakwakmrg.com 121303 1
ckonkatsunet.com 121303 2
I have already tried this line but it does not give the result I want:
df.groupby('orgid').count['domain'].reset_index()
Can anybody help?
解决方案
You can call rank
on the groupby
object and pass param method='first'
:
In [61]:
df['domainId'] = df.groupby('orgid')['orgid'].rank(method='first')
df
Out[61]:
domain orgid domainId
0 csyunshu.com 108299 1
1 dshu.com 108299 2
2 bbbdshu.com 108299 3
3 cwakwakmrg.com 121303 1
4 ckonkatsunet.com 121303 2
If you want to overwrite the column you can do:
df['domain'] = df.groupby('orgid')['orgid'].rank(method='first')
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