# Problems about the get.groups command

**URL:** <https://forum.mothur.org/t/problems-about-the-get-groups-command/1485>\
**Category:** Commands in mothur\
**Created:** [September 2, 2013, 7:56am UTC](https://forum.mothur.org/t/problems-about-the-get-groups-command/1485 "2013-09-02T07:56:23Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![songer](https://avatars.discourse-cdn.com/v4/letter/s/ecb155/32.png) [@songer](https://forum.mothur.org/u/songer)\
**Post date:** [September 2, 2013, 7:56am UTC](https://forum.mothur.org/t/problems-about-the-get-groups-command/1485/1 "2013-09-02T07:56:23Z")

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Hi, all!  
I met a problem about get.groups command, when I did the command I found that I didn’t have the group=MOCK.W7 file. What should I do then?

The command is like this: get.groups(fasta=W7.shhh.trim.unique.good.filter.unique.precluster.pick.pick.fasta, group=W7.shhh.good.pick.pick.groups, name=W7.shhh.trim.unique.good.filter.unique.precluster.pick.pick.names, group=MOCK.W7). I don’t have the MOCK.W7 file and don’t know how to generate it.

I’m waiting for your help! 🙂  
songer  
9/02

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**Author:** ![pschloss](https://yyz2.discourse-cdn.com/flex036/user_avatar/forum.mothur.org/pschloss/32/4_2.png) [@pschloss](https://forum.mothur.org/u/pschloss)\
**Post date:** [September 3, 2013, 12:06pm UTC](https://forum.mothur.org/t/problems-about-the-get-groups-command/1485/2 "2013-09-03T12:06:12Z")

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Did you sequence a mock community with your samples? What was it’s group name?

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**Author:** ![songer](https://avatars.discourse-cdn.com/v4/letter/s/ecb155/32.png) [@songer](https://forum.mothur.org/u/songer)\
**Post date:** [September 5, 2013, 1:27am UTC](https://forum.mothur.org/t/problems-about-the-get-groups-command/1485/3 "2013-09-05T01:27:10Z")

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Thanks for your reply. I did not know how to sequence a mock community with samples. Can I ignore this error analysis step? Is it necessary to the data process?  
I’m waiting for the help. 🙂 Thanks!

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**Author:** ![pschloss](https://yyz2.discourse-cdn.com/flex036/user_avatar/forum.mothur.org/pschloss/32/4_2.png) [@pschloss](https://forum.mothur.org/u/pschloss)\
**Post date:** [September 5, 2013, 11:41am UTC](https://forum.mothur.org/t/problems-about-the-get-groups-command/1485/4 "2013-09-05T11:41:59Z")

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Yeah, to know the error rate for your data, you need to sequence a mock community in parallel. There is a growing chorus of papers suggesting that people include a mock community and report their error rates.

If you don’t do it, then you need to skip the analysis.

Pat