# How to replace all values in an array with missing values?

**URL:** <https://discourse.julialang.org/t/how-to-replace-all-values-in-an-array-with-missing-values/75467>\
**Category:** General Usage\
**Tags:** question, arrays, nan, missing-values\
**Created:** [January 30, 2022, 2:36pm UTC](https://discourse.julialang.org/t/how-to-replace-all-values-in-an-array-with-missing-values/75467 "2022-01-30T14:36:10Z")\
**Posts on this page:** 1\
**Showing post:** 26

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**Author:** ![Jeff\_Emanuel](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/jeff_emanuel/32/15440_2.png) [@Jeff\_Emanuel](https://discourse.julialang.org/u/Jeff_Emanuel)\
**Post date:** [January 31, 2022, 5:50pm UTC](https://discourse.julialang.org/t/how-to-replace-all-values-in-an-array-with-missing-values/75467/26 "2022-01-31T17:50:27Z")

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Depending on what you are doing, NaNs can propagate so that all your data become NaN and you are stuck backtracking to see where the offending NaN was generated that destroyed everything in its wake. In the past, at least, arithmetic with NaN was far slower than with non-NaNs. In an earlier project I worked on, we had code to replace NaN sentinels before to any calculation, even if the calculations didn’t result in NaN propagation corrupting any other values.

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