Adjust the decimals in scientific notation with Plots.jl

New to Julia
,
1

Hello!
I try to publish my figures so I need to edit them as nicely as possible.
I have trouble adjusting the format of my ylabel.

I would like to keep a scientific notation, but Plots.jl is automatically set to a two digits precision.
I would like to keep it to one (else, it takes too much place in subplots).

For example :

using Plots
x = 0:1:10
plot(x, x*1e-6)

How can I keep the ylabel with a format like 2.5x10^-6 instead of 2.50x10^-6 ?

I guess I should use yformatter, but I could not find a documentation or a tutorial to apply.
(I also take recommendations of backends for publication-grade figures)
Thanks!

1 Like
2

There are some examples here in discourse. See if this one helps.

With the latest recommended Format.jl package, try:

using Format, Plots
x = 0:1:10
plot(x, x*1e-6, yformatter = x -> cfmt( "%.1e", x), tickfontsize=6)
1 Like
3 
1 dependency successfully precompiled in 1 seconds. 537 already precompiled.
  1 dependency had output during precompilation:
┌ Formatting
│  ┌ Warning: DEPRECATION NOTICE
│  │ 
│  │ Formatting.jl has been unmaintained for a while, with some serious
│  │ correctness bugs compromising the original purpose of the package. As a result,
│  │ it has been deprecated - consider using an alternative, such as
│  │ `Format.jl` (https://github.com/JuliaString/Format.jl) or the `Printf` stdlib directly.
│  │ 
│  │ If you are not using Formatting.jl as a direct dependency, please consider
│  │ opening an issue on any packages you are using that do use it as a dependency.
│  │ From Julia 1.9 onwards, you can query `]why Formatting` to figure out which
│  │ package originally brings it in as a dependency.
│  └ @ Formatting ~/.julia/packages/Formatting/3VxOt/src/Formatting.jl:12
└

I will try to see what Format.jl can do…

4

Please refer to the example I have added above.

5

I would prefer a notation with x10^n if it is not too hard.

6

I don’t know of an easy way, but the following is within reach, with some more labour:

using Plots

x = 0:1:10
p = plot(x, x*1e-6, yformatter=:scientific)
yt = yticks(p)
# Edit yt programmatically (done here manually):
yt[1][2] .= ["0", "2.5×10^{−6}", "5.0×10^{−6}", "7.5×10^{−6}", "1.0×10^{−5}"]

plot!(p, yticks=yt[1], tickfontsize=6)

With a bit more work below.

CODE: to programmatically edit scientific plot ticks 
using Format, Plots

function sci_ticks(yt; precision=1)
    # "×" can be typed by \times<tab>
    vs = [String.(split(y,'×')) for y in yt[1][2]]
    ix = findall(x->length(x)==1, vs)
    for i in eachindex(vs)
        i ∈ ix ? (vs[i] = [vs[i][1], ""]) : (vs[i][2] = "×" * vs[i][2])
    end
    ystr = format.(parse.(Float64, first.(vs)), precision=precision)
    yt[1][2] .= ystr .* last.(vs)
    return yt[1]
end

x = 0:1:10
p = plot(x, x*1e-6, yformatter=:scientific)
plot!(p, yticks=sci_ticks(yticks(p); precision=1), tickfontsize=6)
1 Like
7

Actually, there is a simple way to handle your example:

plot(x, x*1e-6, yformatter=x->round(x,sigdigits=1))
2 Likes
8

First, thank you very much for all your answers.
It is not clear to me if yformatter does format only the yticks or the values themselves.
Anyhow, with your new solution, I cannot for example have the value with no digits
(like 2x10^-6 instead of 2.0x10^-6).
(I tried that : )
plot(x, x*1e-6, yformatter=x->round(x,sigdigits=0))

9

Indeed, this simple approach doesn’t seem to work when asking for zero digits for numbers < 1.

Another alternative using Printf.jl:

using Printf
plot(x, x*1e-6, yformatter=x->join(split(@sprintf("%.0e", x), 'e'), "×10^{") * "}")