CODEWITHSUNDEEP
juliabar-chart
Arsalan
Arsalan

Reputation: 373

groupedbar in StatsPlots(Julia) modifies the input array weirdly

I am encountering a strange issue! I am trying to plot using groupedbar but I facing this strange issue. here is the code to generate the data and plot it:

nam = string.(repeat(1:20, outer=2))
sx = repeat(["Pre-Polarization", "Post-Polarization"], inner = 20)
c = 1:40
groupedbar(nam, c, group = sx, xlabel = "Groups", ylabel = "Scores",
        title = "Scores by group and category", bar_width = 0.9,
        lw = 0, framestyle = :box)

And I get the following results:

enter image description here

Does anybody know the reason it's happening?

Upvotes: 1

Views: 722

Answers (2)

AsgerHB
AsgerHB

Reputation: 335

If strings are required, you can exploit the fact that space comes before numbers in lexicographical sort, such that " 3" < "10"

For example:

nam = (repeat(1:20, outer=2))

# Space sorts before numbers
nam = [ n >= 20 ? "$n" : 
        n >= 10 ? " $n" :
        "  $n" 
        for n in nam]

sx = repeat(["Pre-Polarization", "Post-Polarization"], inner = 20)
c = 1:40
groupedbar(nam, c, group = sx, xlabel = "Groups", ylabel = "Scores",
    title = "Scores by group and category", bar_width = 0.9,
    lw = 0, framestyle = :box)

A grouped bar chart showing two groups of steadily increasing values. The values on the x axis are ordered correctly.

The keen-eyed observer might notice a slight misalignment of the numbers now. This can be fixed by using either U+200B Zero Width Space or an U+2063 Invisible Seperator in place of the regular space, though it would make the code harder to read.

Upvotes: 0

Bill
Bill

Reputation: 6086

The reason the X axis values look strange is the Julia is sorting the numbers as strings, not as numbers. This means, for example, that "3" > "20" in your code for nam.

To fix this you should not stringify nam before it is plotted. So use 

nam = repeat(1:20, outer=2)

in the above code.

Upvotes: 2

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