# Set all cells below a certain value to NaN

**URL:** <https://forum.generic-mapping-tools.org/t/set-all-cells-below-a-certain-value-to-nan/2551>\
**Category:** Q&A\
**Created:** [January 23, 2022, 6:02pm UTC](https://forum.generic-mapping-tools.org/t/set-all-cells-below-a-certain-value-to-nan/2551 "2022-01-23T18:02:00Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Andreas](https://avatars.discourse-cdn.com/v4/letter/a/ee7513/32.png) [@Andreas](https://forum.generic-mapping-tools.org/u/Andreas)\
**Post date:** [January 23, 2022, 6:02pm UTC](https://forum.generic-mapping-tools.org/t/set-all-cells-below-a-certain-value-to-nan/2551/1 "2022-01-23T18:02:00Z")

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I’m looking for a function to set all grid cells that are below (or above) a certain value to NaN. I thought this function existed in `grdmath`, but I cannot find it! Doesn’t this function exist?

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**Author:** ![Andreas](https://avatars.discourse-cdn.com/v4/letter/a/ee7513/32.png) [@Andreas](https://forum.generic-mapping-tools.org/u/Andreas)\
**Post date:** [January 23, 2022, 6:43pm UTC](https://forum.generic-mapping-tools.org/t/set-all-cells-below-a-certain-value-to-nan/2551/2 "2022-01-23T18:43:45Z")

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Nevermind. [https://docs.generic-mapping-tools.org/latest/grdclip.html](https://docs.generic-mapping-tools.org/latest/grdclip.html) Does what I’m looking for.