# Colormap logscale using Plot
**URL:** https://discourse.julialang.org/t/colormap-logscale-using-plot/44759
**Category:** General Usage
**Tags:** plots
**Created:** [August 11, 2020, 8:52pm UTC](https://discourse.julialang.org/t/colormap-logscale-using-plot/44759 "2020-08-11T20:52:35Z")
**Posts on this page:** 8
**Page:** 1
### Author:  [@sriharitn](https://discourse.julialang.org/u/sriharitn)
#### Post date: [August 11, 2020, 8:52pm UTC](https://discourse.julialang.org/t/colormap-logscale-using-plot/44759/1 "2020-08-11T20:52:36Z")
I’m trying to build a 3D surface plot with color in log10 scale. I just want the color to be in the log10 scale NOT the actual values itself.
```julia
N = 51
x = range(-10, stop = 10, length = N)
y = x
f(x,y)=x^2+y^2
Plots.plot(x,y,f,st=:surface,color=:jet,camera=(25,65))
```
See below:
Here is the output with Logscale created using GNUPLOT.
---
### Author:  [@BeastyBlacksmith](https://discourse.julialang.org/u/BeastyBlacksmith)
#### Post date: [August 11, 2020, 8:58pm UTC](https://discourse.julialang.org/t/colormap-logscale-using-plot/44759/2 "2020-08-11T20:58:42Z")
Check out the [documentation](http://docs.juliaplots.org/latest/generated/colorschemes/#ColorGradient). It is pretty
---
### Author:  [@sriharitn](https://discourse.julialang.org/u/sriharitn)
#### Post date: [August 12, 2020, 4:41pm UTC](https://discourse.julialang.org/t/colormap-logscale-using-plot/44759/3 "2020-08-12T16:41:38Z")
Thank you. The link really helped.
I have used log scale, but still unable to reproduce the chart from `gnuplot`.
```julia
using Plots
N = 51
x = range(-10, stop = 10, length = N)
y = x
f(x,y)=x^2+y^2
out = Plots.plot(x,y,f,st=:surface,color= cgrad(:jet,scale=log),camera=(25,65))
savefig(out,"out.png")
```
The key driving factor is `z` the need to included in `cgrad`. How would one modify `z` to get a replica of my original plot.
---
### Author:  [@sriharitn](https://discourse.julialang.org/u/sriharitn)
#### Post date: [August 12, 2020, 4:46pm UTC](https://discourse.julialang.org/t/colormap-logscale-using-plot/44759/4 "2020-08-12T16:46:48Z")
I figured it out:
```julia
using Plots
N = 51
x = range(-10, stop = 10, length = N)
y = x
f(x,y)=x^2+y^2
z = [0.001,0.01,0.05,5,50,100,200]
out = Plots.plot(x,y,f,st=:surface,color= cgrad(:jet,z,scale=log),camera=(25,65))
savefig(out,"out.png")
```
It would be great if we can automatically estimate values `z` like `gnuplot`.
---
### Author:  [@dpsanders](https://discourse.julialang.org/u/dpsanders)
#### Post date: [August 12, 2020, 7:20pm UTC](https://discourse.julialang.org/t/colormap-logscale-using-plot/44759/5 "2020-08-12T19:20:27Z")
You can do e.g.
```julia
z = 10 .^ (1:0.01:2)
```
---
### Author:  [@Ininterrompue](https://discourse.julialang.org/u/Ininterrompue)
#### Post date: [November 21, 2022, 9:38pm UTC](https://discourse.julialang.org/t/colormap-logscale-using-plot/44759/6 "2022-11-21T21:38:50Z")
I’m trying to do this with contours but it’s not working.
```julia
using Plots; pyplot()
f(x, y) = exp(x^2 + y^2)
x = range(-3, 3, length=100)'
y = range(-3, 3, length=100)
z = @. f(x, y)
zc = 10 .^ range(log10(minimum(z)), log10(maximum(z)), length=100)
contourf(x, y, z, colorbar_scale=:log10, color=cgrad(:turbo, zc, scale=:log10))
```
But most of the plot is blue, when it should be a more gradual gradient. In other words, I’d like to have something like [this](https://matplotlib.org/stable/tutorials/colors/colormapnorms.html), or [this](https://matplotlib.org/stable/gallery/images_contours_and_fields/contourf_log.html), where each level is an order of magnitude. Is this possible?
---
### Author:  [@rafael.guerra](https://discourse.julialang.org/u/rafael.guerra)
#### Post date: [November 21, 2022, 11:04pm UTC](https://discourse.julialang.org/t/colormap-logscale-using-plot/44759/7 "2022-11-21T23:04:36Z")
You can play with `plot()`'s keyword arguments `levels` and `colorbar_ticks` to produce discrete or smooth contour maps:
---
### Author:  [@Ininterrompue](https://discourse.julialang.org/u/Ininterrompue)
#### Post date: [November 22, 2022, 3:26am UTC](https://discourse.julialang.org/t/colormap-logscale-using-plot/44759/9 "2022-11-22T03:26:17Z")
Ok I figured it out. Unfortunately it requires plotting \log z instead of z directly…code below for reference.
```julia
using Plots, LaTeXStrings
pyplot()
h(x, y) = exp(x^2 + y^2)
x = range(-3, 3, length=100) |> adjoint
y = range(-3, 3, length=100)
z = @. h(x, y)
tv = 0:8
tl = [L"10^{%$i}" for i in tv]
contourf(x, y, log10.(z), color=:turbo, levels=8, colorbar_ticks=(tv, tl),
aspect_ratio=:equal,
title=L"\exp(x^{2} + y^{2})",
xlabel=L"x",
ylabel=L"y")
```
