# How to retrieve reads from fasta file based on a list of identifier? name

**URL:** <https://help.galaxyproject.org/t/how-to-retrieve-reads-from-fasta-file-based-on-a-list-of-identifier-name/4781>\
**Category:** Uncategorized\
**Tags:** fasta-manipulation, text-manipulation\
**Created:** [November 4, 2020, 6:10am UTC](https://help.galaxyproject.org/t/how-to-retrieve-reads-from-fasta-file-based-on-a-list-of-identifier-name/4781 "2020-11-04T06:10:23Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![dacosta](https://avatars.discourse-cdn.com/v4/letter/d/e8c25b/32.png) [@dacosta](https://help.galaxyproject.org/u/dacosta)\
**Post date:** [November 4, 2020, 6:10am UTC](https://help.galaxyproject.org/t/how-to-retrieve-reads-from-fasta-file-based-on-a-list-of-identifier-name/4781/1 "2020-11-04T06:10:23Z")

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Hello,

Is there a tool in usegalaxy that can help me retrieve reads from a fasta file (8Gb) based on a list of read identifier names (~150)? The list of identifer names is in a text file but I can convert to fasta or something else. I’d then run the selected reads through blast for ID.

Thanks for any help.

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**Author:** ![gallardoalba](https://sea2.discourse-cdn.com/flex020/user_avatar/help.galaxyproject.org/gallardoalba/32/1903_2.png) [@gallardoalba](https://help.galaxyproject.org/u/gallardoalba)\
**Post date:** [November 4, 2020, 7:59am UTC](https://help.galaxyproject.org/t/how-to-retrieve-reads-from-fasta-file-based-on-a-list-of-identifier-name/4781/2 "2020-11-04T07:59:00Z")

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Hi @dacosta,  
in order to extract a set of reads based on a list of identifiers you can use the seq\_filter\_by\_id tool. Previously you will need to set the text file datatype as tabular.

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**Author:** ![dacosta](https://avatars.discourse-cdn.com/v4/letter/d/e8c25b/32.png) [@dacosta](https://help.galaxyproject.org/u/dacosta)\
**Post date:** [November 4, 2020, 10:08am UTC](https://help.galaxyproject.org/t/how-to-retrieve-reads-from-fasta-file-based-on-a-list-of-identifier-name/4781/3 "2020-11-04T10:08:02Z")

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Thank you so much for your reply @gallardoalba. I might be mistaken but it looks like I’d need to use this tool with python. Thanks in part to your reply, I was able to find the filter fasta tool which does the same thing but is an online usegalaxy tool.

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**Author:** ![gallardoalba](https://sea2.discourse-cdn.com/flex020/user_avatar/help.galaxyproject.org/gallardoalba/32/1903_2.png) [@gallardoalba](https://help.galaxyproject.org/u/gallardoalba)\
**Post date:** [November 4, 2020, 10:54am UTC](https://help.galaxyproject.org/t/how-to-retrieve-reads-from-fasta-file-based-on-a-list-of-identifier-name/4781/4 "2020-11-04T10:54:48Z")

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Yes, you can find that tool in Galaxy as _Filter sequences by ID_ (if you look for seq\_filter\_by\_id in the tool search bar you will get the same result).

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**Author:** ![dacosta](https://avatars.discourse-cdn.com/v4/letter/d/e8c25b/32.png) [@dacosta](https://help.galaxyproject.org/u/dacosta)\
**Post date:** [November 4, 2020, 6:34pm UTC](https://help.galaxyproject.org/t/how-to-retrieve-reads-from-fasta-file-based-on-a-list-of-identifier-name/4781/5 "2020-11-04T18:34:42Z")

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Ahhh I see! I only searched for a portion of that keyword originally. Thanks again @gallarsoalba