CODEWITHSUNDEEP
plotgnuplotbar-chart
H W
H W

Reputation: 153

explicit the x-value for plotting in gnuplot

In GNUPLOT, I would like to plot 5 values on a single bar chart, separated with some spacing in between. If I have data formatted as such:

3342336, 3375103, 7110653, 32770, 0

where those 5 values are the y-values, how can I specify the x-values myself for where they should belong?

For example, I would like my bar chart to have each entry be of length 1, so I plot y-value 3342336 at x-value 1, y-value 3375103 at x-value 3, y-value 7110653 at x-value 5, y-value 32770 at x-value 7, and y-value 0 at x-value 9.

I would appreciate any example code that can achieve this. Thanks.

Upvotes: 1

Views: 917

Answers (1)

Matthew
Matthew

Reputation: 7590

If your data is in one row as shown, you can achieve this by using the plot for syntax looping over the column index, and calculating the x value from that index. We can grab the column by using the column function which retrieves the specified column number.

set boxwidth 1
set datafile separator comma    # only if data is comma separated
plot for [i=1:5] (2*i-1):(column(i)) with boxes

If we need to ensure the same line type is used each time, we can explicitly state it in the plot command.

plot for [i=1:5] (2*i-1):(column(i)) with boxes lt 1

enter image description here

Additionally, if a key is to be generated, and we don't wish each plot statement to generate one, we can test for and only give a nonempty title on the first iteration (an empty title is treated the same as no title).

plot for [i=1:5] (2*i-1):(column(i)) with boxes lt 1 title (i==1)?"Title":""

If your data is separated into rows as is the normal format, this can be obtained a different way.

Gnuplot has several pseuduocolumns (see help pseudocolumns for details). In your case, column 0 is of interest. Column 0 gives the line number of the data starting at 0. Thus to get sequential odd numbers like that, you can use 2*$0+1.

For example, if your data (stored in datafile.txt) looks like

3342336
3375103
7110653
32770
0

and you wish to plot boxes of length 1 at those values, you can do

set boxwidth 1
plot "datafile.txt" u (2*$0+1):1 with boxes

Upvotes: 1

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