# How to use Log10 axis scale for Makie heatmaps

**URL:** https://discourse.julialang.org/t/how-to-use-log10-axis-scale-for-makie-heatmaps/75722
**Category:** Visualization
**Tags:** question, plotting, visualization, makie
**Created:** [February 3, 2022, 1:45pm UTC](https://discourse.julialang.org/t/how-to-use-log10-axis-scale-for-makie-heatmaps/75722 "2022-02-03T13:45:00Z")
**Posts on this page:** 3
**Page:** 1

<div class="post-metadata">

### Author: ![fnoessler](https://avatars.discourse-cdn.com/v4/letter/f/eb9ed0/32.png) [@fnoessler](https://discourse.julialang.org/u/fnoessler)
#### Post date: [February 3, 2022, 1:45pm UTC](https://discourse.julialang.org/t/how-to-use-log10-axis-scale-for-makie-heatmaps/75722/1 "2022-02-03T13:45:00Z")

</div>

Hello,

I cannot figure out how to properly set a log10 axis scale for heatmaps. I get an error of invalid x-limits even if I set positive axis limits. I know log10 is not defined for negative values (when I dont want a complex number). As a workaround I can manually specify the ticklabels, but this is quite some work. The same code works for a scatterplot. Many thanks for your help!

```julia
using GLMakie

## Heatmap with log10 scales axes does not work
## even when I set axis limits
let
    xs = [10^2, 10^2, 10^3, 10^3]
    ys = [10^-3, 10^-2, 10^-3, 10^-2]
    zs = [1, 2, 3, 4]
    fig = Figure()
    ax1 = Axis(fig[1,1]; yscale=log10, xscale=log10) 
    limits!(ax1, 10^1, 10^3, 10^-3, 10^-1)
    heatmap!(ax1, xs, ys, zs)
    fig
end
# LoadError: Found invalid x-limits (-350.0f0, 1450.0f0) for scale log10 which is defined on the interval 0.0..Inf (open)

## it works for a scatterplot
let
    xs = [10^2, 10^2, 10^3, 10^3]
    ys = [10^-3, 10^-2, 10^-3, 10^-2]
    zs = [1, 2, 3, 4]
    fig = Figure()
    ax1 = Axis(fig[1,1]; yscale=log10, xscale=log10) 
    scatter!(xs, ys; color=zs, markersize=50)
    fig
end

## workaround: set manual ticklabels
let
    xs = [1, 1, 2, 2]
    ys = [1, 2, 1, 2]
    zs = [1, 2, 3, 4]
    fig = Figure()
    ax1 = Axis(fig[1,1]; 
        xticks=(1:2, ["10²", "10³"]),
        yticks=(1:2, ["10⁻³", "10⁻²"])) 
    heatmap!(xs, ys, zs)
    fig
end

```

---

<div class="post-metadata">

### Author: ![ederag](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/ederag/32/4106_2.png) [@ederag](https://discourse.julialang.org/u/ederag)
#### Post date: [February 3, 2022, 2:50pm UTC](https://discourse.julialang.org/t/how-to-use-log10-axis-scale-for-makie-heatmaps/75722/2 "2022-02-03T14:50:58Z")

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Confirmed with `GLMakie v0.5.2`, `Makie v0.16.3`.  
Makie already has an open [issue for non-linear grids](https://github.com/JuliaPlots/Makie.jl/issues/748#issuecomment-851056745) which is not exactly about log scale, but might be related.  
The link contains some code that might help to workaround this.

Since you already have a manual workaround, but generating tick labels by hand is cumbersome,  
you might be interested in

```julia
custom_formatter(values) = map(
		v -> "10" * Makie.UnicodeFun.to_superscript(round(Int64, v)),
		values
	)

```

used in [https://github.com/JuliaPlots/Makie.jl/issues/1405](https://github.com/JuliaPlots/Makie.jl/issues/1405) for log scale colorbar  
(see inside the first “Code for the above figure” revealer).

---

<div class="post-metadata">

### Author: ![fnoessler](https://avatars.discourse-cdn.com/v4/letter/f/eb9ed0/32.png) [@fnoessler](https://discourse.julialang.org/u/fnoessler)
#### Post date: [February 3, 2022, 3:07pm UTC](https://discourse.julialang.org/t/how-to-use-log10-axis-scale-for-makie-heatmaps/75722/3 "2022-02-03T15:07:52Z")

</div>

Thanks for you reply! I was not aware of the automatic way to make superscript unicode numbers. I tried it before with the `latextring` function from the `LaTeXStrings` package. This was working, but then the font also changes.

edit: here was my ugly code

```julia
values = [0.001, 0.01]
latexstring.(repeat(["10^{"], length(values)) .* string.(Int.(log10.(values))) .* "}" )

```