# Plots.jl mask values in heatmap

**URL:** <https://discourse.julialang.org/t/plots-jl-mask-values-in-heatmap/69223>\
**Category:** Visualization\
**Tags:** plots\
**Created:** [October 5, 2021, 8:23am UTC](https://discourse.julialang.org/t/plots-jl-mask-values-in-heatmap/69223 "2021-10-05T08:23:23Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![weymouth](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/weymouth/32/15839_2.png) [@weymouth](https://discourse.julialang.org/u/weymouth)\
**Post date:** [October 5, 2021, 8:23am UTC](https://discourse.julialang.org/t/plots-jl-mask-values-in-heatmap/69223/1 "2021-10-05T08:23:23Z")

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I’m trying to mask out some values of a rectangular array in a heatmap.

It seems like it should be easy using alpha…

```julia
heatmap(rand(10,10),alpha=rand(10,10) .> 0.5)

```

![temp](https://global.discourse-cdn.com/julialang/original/3X/2/d/2d9e89a97c44b85364a0645c7b8f61cfdbbe7746.png)

But this blanks out **stripes** instead of individual **cells**. What’s going on?

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**Author:** ![rafael.guerra](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/rafael.guerra/32/216610_2.png) [@rafael.guerra](https://discourse.julialang.org/u/rafael.guerra)\
**Post date:** [October 5, 2021, 8:47am UTC](https://discourse.julialang.org/t/plots-jl-mask-values-in-heatmap/69223/2 "2021-10-05T08:47:14Z")

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Maybe you could use `NaN` to mask the undesirable values as a workaround?

```julia
using Plots; gr()
m = rand(10,10)
m2 = copy(m)
m2[m .> 0.5] .= NaN 
heatmap(m2)

```

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<div class="post-metadata">

**Author:** ![weymouth](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/weymouth/32/15839_2.png) [@weymouth](https://discourse.julialang.org/u/weymouth)\
**Post date:** [October 5, 2021, 11:56am UTC](https://discourse.julialang.org/t/plots-jl-mask-values-in-heatmap/69223/3 "2021-10-05T11:56:31Z")

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Thanks. I was hoping to use alpha so I could smooth the transition, but this will work in the meantime.

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**Author:** ![BeastyBlacksmith](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/beastyblacksmith/32/4741_2.png) [@BeastyBlacksmith](https://discourse.julialang.org/u/BeastyBlacksmith)\
**Post date:** [October 5, 2021, 2:21pm UTC](https://discourse.julialang.org/t/plots-jl-mask-values-in-heatmap/69223/4 "2021-10-05T14:21:20Z")

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Please open an issue on [https://github.com/JuliaPlots/Plots.jl/issues](https://github.com/JuliaPlots/Plots.jl/issues)

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**Author:** ![weymouth](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/weymouth/32/15839_2.png) [@weymouth](https://discourse.julialang.org/u/weymouth)\
**Post date:** [October 5, 2021, 6:01pm UTC](https://discourse.julialang.org/t/plots-jl-mask-values-in-heatmap/69223/6 "2021-10-05T18:01:02Z")

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Ok  
[https://github.com/JuliaPlots/Plots.jl/issues/3865#issue-1016626799](https://github.com/JuliaPlots/Plots.jl/issues/3865#issue-1016626799)