# Standard deviation plot

**URL:** <https://forum.generic-mapping-tools.org/t/standard-deviation-plot/2326>\
**Category:** Q&A\
**Created:** [November 19, 2021, 9:56am UTC](https://forum.generic-mapping-tools.org/t/standard-deviation-plot/2326 "2021-11-19T09:56:55Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![lucacastro95](https://avatars.discourse-cdn.com/v4/letter/l/ad7895/32.png) [@lucacastro95](https://forum.generic-mapping-tools.org/u/lucacastro95)\
**Post date:** [November 19, 2021, 9:56am UTC](https://forum.generic-mapping-tools.org/t/standard-deviation-plot/2326/1 "2021-11-19T09:56:55Z")

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I dears, is everything fine?

I need to add a standard deviation curve to my plot but cannot find much on internet. I have a dataset in .txt that contains 3 columns as shown below. The third column is the standard deviation of the second column values.

 ![standarddeviationdata](https://canada1.discourse-cdn.com/flex047/uploads/gmt/original/2X/e/e093d310ce74a807f0d873fb21fc65a93f1c1553.png)

I plotted the first two columns but cannot find a good way to plot easely the third. I tried to preprocess the data in Excel but the result was not actually what I expected. Is there any command or argument I could use directly on gmt? I found on internet that there is a -E argument but it displays error bars and not a continuous line.

Thank you so much for your help 🙂

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**Author:** ![Esteban82](https://yyz1.discourse-cdn.com/flex047/user_avatar/forum.generic-mapping-tools.org/esteban82/32/54_2.png) [@Esteban82](https://forum.generic-mapping-tools.org/u/Esteban82)\
**Post date:** [November 19, 2021, 12:22pm UTC](https://forum.generic-mapping-tools.org/t/standard-deviation-plot/2326/2 "2021-11-19T12:22:00Z")

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You can use -i to select the columns of your dataset.

E.g… try adding `-i0,2` to plot the first vs third column.

> **[gmt — GMT 6.2.0 documentation](https://docs.generic-mapping-tools.org/latest/gmt.html#the-i-option)**

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<div class="post-metadata">

**Author:** ![lucacastro95](https://avatars.discourse-cdn.com/v4/letter/l/ad7895/32.png) [@lucacastro95](https://forum.generic-mapping-tools.org/u/lucacastro95)\
**Post date:** [November 20, 2021, 11:21am UTC](https://forum.generic-mapping-tools.org/t/standard-deviation-plot/2326/3 "2021-11-20T11:21:17Z")

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Thank you so much 🙂 !