# Discriminate between NaN and Inf in plots
**URL:** https://discourse.julialang.org/t/discriminate-between-nan-and-inf-in-plots/112171
**Category:** Visualization
**Tags:** question
**Created:** [March 27, 2024, 7:21am UTC](https://discourse.julialang.org/t/discriminate-between-nan-and-inf-in-plots/112171 "2024-03-27T07:21:31Z")
**Posts on this page:** 8
**Page:** 1
### Author:  [@Fourier](https://discourse.julialang.org/u/Fourier)
#### Post date: [March 27, 2024, 7:21am UTC](https://discourse.julialang.org/t/discriminate-between-nan-and-inf-in-plots/112171/1 "2024-03-27T07:21:31Z")
I have a plot where some values originate from devision by 0 and some originate from 0/0, I would like to add new colours to the heatmap to descriminate between them.
Does anyone have an idea on how to do this in plots.jl?
---
### Author:  [@Sevi](https://discourse.julialang.org/u/Sevi)
#### Post date: [March 27, 2024, 8:00am UTC](https://discourse.julialang.org/t/discriminate-between-nan-and-inf-in-plots/112171/2 "2024-03-27T08:00:20Z")
I don’t know if one can specify custom colors for `Inf` and `NaN` directly, but a possible workaround would be to manually plot something in the place of the infinities/NaNs with `scatter!`.
Here’s an example (note that I transposed the data for the heatmap, otherwise the definitions of the x and y axes will be flipped for `heatmap` and `scatter!`):
```julia
using Plots
N = 50
rawData = rand(N, N)
nanPointCoordinates = rand(CartesianIndices((1:N, 1:N)), 500)
infPointCoordinates = rand(CartesianIndices((1:N, 1:N)), 500)
rawData[nanPointCoordinates] .= NaN
rawData[infPointCoordinates] .= Inf
p = heatmap(transpose(rawData); c=:viridis)
scatter!(p, Tuple.(findall(isnan, rawData)); label="NaNs", markers=:square, markerstrokewidth=0, markercolor=:red, markersize=3)
scatter!(p, Tuple.(findall(isinf, rawData)); label="Infs", markers=:square, markerstrokewidth=0, markercolor=:black, markersize=3)
```
This will produce something like this (you would have to play around with the shapes/sizes/colors of the markers of course – also how to find the right x/y coordinates in your case, I just used the indices)
---
### Author:  [@Fourier](https://discourse.julialang.org/u/Fourier)
#### Post date: [March 27, 2024, 8:17am UTC](https://discourse.julialang.org/t/discriminate-between-nan-and-inf-in-plots/112171/3 "2024-03-27T08:17:49Z")
This is a very creative solution, thank you very much : )
---
### Author:  [@joa-quim](https://discourse.julialang.org/u/joa-quim)
#### Post date: [March 27, 2024, 1:38pm UTC](https://discourse.julialang.org/t/discriminate-between-nan-and-inf-in-plots/112171/4 "2024-03-27T13:38:36Z")
An alternative with grids and playing with the colormap
```julia
using GMT
N = 50;
rawData = rand(N, N);
nanPointCoordinates = rand(CartesianIndices((1:N, 1:N)), 500);
infPointCoordinates = rand(CartesianIndices((1:N, 1:N)), 500);
rawData[nanPointCoordinates] .= NaN;
rawData[infPointCoordinates] .= Inf;
# Convert data into a GMT grid
G = mat2grid(Float32.(rawData));
# Make a colormap with NaNs in gray and Infs in white
C = makecpt(range=(0,1), overrule_bg=true, conf=(COLOR_FOREGROUND=:white, COLOR_NAN=:gray));
viz(G, cmap=C, colorbar=true)
```
---
### Author:  [@rafael.guerra](https://discourse.julialang.org/u/rafael.guerra)
#### Post date: [March 27, 2024, 7:53pm UTC](https://discourse.julialang.org/t/discriminate-between-nan-and-inf-in-plots/112171/5 "2024-03-27T19:53:51Z")
Fyi, it is also possible to get this using Plots’ heatmap():
> **Plots' heatmap code**
>
> ```julia
> # (continued from code above)
> using Colors, ColorSchemes, Plots; gr()
> theme(:dark)
>
> c0, c3 = colorant"white", colorant"red" # NaN's are labelled white, Inf's red
> m = 16
> cscheme1 = palette(ColorScheme([c0; ColorSchemes.viridis.colors; c3]), m+2)
> z1, z2 = extrema(x for x in rawData if isfinite(x))
> dz = (z2 - z1)/m
> Z0 = replace(rawData, NaN => z1 - dz, Inf => z2 + dz)
>
> heatmap(Z0, c=cscheme1, lims=(0.5, N+0.5), ratio=1, dpi=600)
> annotate!(N+8, N+0.5, text("Inf", :red, 9))
> annotate!(N+8, 1, text("NaN", :white, 9))
>
> ```
---
### Author:  [@rocco\_sprmnt21](https://discourse.julialang.org/u/rocco_sprmnt21)
#### Post date: [March 27, 2024, 9:15pm UTC](https://discourse.julialang.org/t/discriminate-between-nan-and-inf-in-plots/112171/6 "2024-03-27T21:15:16Z")
> [@rafael.guerra](#):
>
> it is also possible to get this using Plots’ heatmap():
what is the syntax?
---
### Author:  [@rafael.guerra](https://discourse.julialang.org/u/rafael.guerra)
#### Post date: [March 27, 2024, 9:21pm UTC](https://discourse.julialang.org/t/discriminate-between-nan-and-inf-in-plots/112171/7 "2024-03-27T21:21:42Z")
The code has been posted below the plot.
---
### Author:  [@Sevi](https://discourse.julialang.org/u/Sevi)
#### Post date: [March 28, 2024, 6:13pm UTC](https://discourse.julialang.org/t/discriminate-between-nan-and-inf-in-plots/112171/8 "2024-03-28T18:13:05Z")
> [@rafael.guerra](#):
>
> Fyi, it is also possible to get this using Plots’ heatmap():
This is brilliant, thanks for the pointer!