CODEWITHSUNDEEP
gnuplot
aokcula
aokcula

Reputation: 23

Round to leading digit in Gnuplot

Can I define a round function in gnuplot that automatically rounds numbers not to a close integer (like floor etc.) but to the leading digit, like

round(0.00230354) = 0.002 ?

Of course, I could multiply every value by the correct power of 10 and then floor it. But in order to do so I would need to look at every number individually. I would want to use the function to label color bars where I determine the tics positions dynamically with the stats command for varying datasets.

Upvotes: 2

Views: 2078

Answers (1)

ewcz
ewcz

Reputation: 13097

you could most likely use sprintf for this task (i.e., to obtain first the "rounded" string representation of the number of interest which is then converted back to a number via the real function):

gnuplot> x = real(sprintf("%.0E", 0.00230354));print x
0.002
gnuplot> x = real(sprintf("%.0E", 0.00260354));print x
0.003

So in terms of a custom function round, the example would look like:

gnuplot> round(x) = real(sprintf("%.0E", x));
gnuplot> print round(0.00230354);
0.002

Or if you wanted just the string representation which you could then use directly for the labels then perhaps the g/G conversion specifier might be more relevant:

gnuplot> s = sprintf("%.1g", 0.00230354); print s
0.002
gnuplot> s = sprintf("%.1g", 0.000000230354); print s
2e-07
gnuplot> s = sprintf("%.1g", 0.000000260354); print s
3e-07

Upvotes: 3

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