one column being needed both in grouping and in j

[ieiwk]

Dear,

data.table is cool. I am learning using it.

Here is a situiation I found no quick solution:
there is one column for which I want to use its sub-string in by, while in j I want to access its other parts.

Please help. Thanks a lot!

[MichaelChirico]

look into .BY. please use the issue tracker for package bugs/feature requests instead of tutorial help -- stackoverflow will be happy to help as well as much faster. cheers!!

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On Sep 23, 2017 7:29 PM, "calvin" ***@***.***> wrote: Dear, data.table is cool. I am learning using it. Here is a situiation I found no quick solution: there is one column for which I want to use its sub-string in *by*, while in *j* I want to access its other parts. Please help. Thanks a lot! — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#2379>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AHQQdc780JH8fs50paTRam8R0vSaE5_uks5slOuKgaJpZM4Phhqc> .

[ieiwk]

Thanks! But .BY is only the sub-string I used to group, while in j I need to access parts other than that sub-string...

[ieiwk]

Also for the issue tracker, am I using it already and correctly?

[renkun-ken]

Duplicate of #1427

[ieiwk]

OK, now I have figured it out. I can use .I in j.