# Not getting fixed contour with "+" for grdcontour

**URL:** <https://forum.generic-mapping-tools.org/t/not-getting-fixed-contour-with-for-grdcontour/2943>\
**Category:** PyGMT Q&A\
**Created:** [May 24, 2022, 6:56am UTC](https://forum.generic-mapping-tools.org/t/not-getting-fixed-contour-with-for-grdcontour/2943 "2022-05-24T06:56:26Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![Edgar](https://avatars.discourse-cdn.com/v4/letter/e/b487fb/32.png) [@Edgar](https://forum.generic-mapping-tools.org/u/Edgar)\
**Post date:** [May 24, 2022, 6:56am UTC](https://forum.generic-mapping-tools.org/t/not-getting-fixed-contour-with-for-grdcontour/2943/1 "2022-05-24T06:56:26Z")

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Hello, so I was trying to get the coordinates for a 170 km contour using:

`fig.grdcontour(grid='SLNAAFSA.nc', interval = +170, D = "contoursl.ll")`

I thought by adding “+” it would give me just the 170 km contour, but the dump contoursl.ll file also includes contours for multiples of 170 (340, 510, 680 and 850 km). May I have some help with this?

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**Author:** ![Joaquim](https://yyz1.discourse-cdn.com/flex047/user_avatar/forum.generic-mapping-tools.org/joaquim/32/16_2.png) [@Joaquim](https://forum.generic-mapping-tools.org/u/Joaquim)\
**Post date:** [May 24, 2022, 11:25am UTC](https://forum.generic-mapping-tools.org/t/not-getting-fixed-contour-with-for-grdcontour/2943/2 "2022-05-24T11:25:43Z")

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man page says

> To indicate a single specific contour you must append a trailing comma to separate it from a contour interval.

So I think it should be `interval = '170,'` (or `interval = "170,"`, I don’t know)

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**Author:** ![seisman](https://yyz1.discourse-cdn.com/flex047/user_avatar/forum.generic-mapping-tools.org/seisman/32/4_2.png) [@seisman](https://forum.generic-mapping-tools.org/u/seisman)\
**Post date:** [May 24, 2022, 1:02pm UTC](https://forum.generic-mapping-tools.org/t/not-getting-fixed-contour-with-for-grdcontour/2943/3 "2022-05-24T13:02:55Z")

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I think @Joaquim is right. You should use `interval="170,"`. The PyGMT documentation for grdcontour needs updates.

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**Author:** ![Edgar](https://avatars.discourse-cdn.com/v4/letter/e/b487fb/32.png) [@Edgar](https://forum.generic-mapping-tools.org/u/Edgar)\
**Post date:** [May 24, 2022, 1:04pm UTC](https://forum.generic-mapping-tools.org/t/not-getting-fixed-contour-with-for-grdcontour/2943/4 "2022-05-24T13:04:09Z")

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Works great, thank you very much!