Gnuplot minimum and maximum boundaries for autoscaling

Question

How can I limit the autoscaling of gnuplot, so that, as example for the y-max, it is at least a certain value and it would autoscale up to fixed \"limit\"?

From loo

Answer 1

Since version 4.6 gnuplot offers a new syntax to specify upper and lower limits for the autoscaling. For your case you could use

set xrange [0:100 < * < 1000]

Quoting from the documentation:

The range in which autoscaling is being performed may be limited by a lower bound <lb> or an upper bound <ub> or both. The syntax is

{ <lb> < } * { < <ub> }

For example

0 < * < 200

sets <lb> = 0 and <ub> = 200.

That syntax can be applied to both the minimum or maximum value of set *range.

To autoscale xmin but keeping it positive, use

set xrange [0<*:]

To autoscale x but keep minimum range of 10 to 50:

set xrange [*<10:50<*]

See the documentation about set xrange for more information.

Answer 2

In this case, you could filter the data and let gnuplot do it's normal auto-scaling:

set yrange [*:*]
plot 'mydatafile' u 1:(($2 >= YMIN && $2 <= YMAX) ? $2 : 1/0)

Answer 3

Since people seem to be interested in this question, I'll add the way I solved this as an answer:

I made the minimum for the autoscaling by inserting a invisible marker in the beginning of the data. That cause the plot to always "show" it, even though it can not bee seen.

Then I implemented the maximum outside of gnuplot (propably could have been possible inside it as well, take a look at mgilson's answer), in a parser script that I have used to prepare the data for gnuplot.

Actually in the script I took all the "clipped out" values, added them to y=0, and made them red. That way I get a "warning", of values being too big to be sensible to graph. (My program monitors pings between two hosts, and there is no sense trying to graph 5s+ latencies => I mark it as connection broken)

Answer 4

I don't think it is possible, either you have autoscaling on no-, min- or max-, or both axis i.e.:

set yrange [FIXED_MIN : FIXED_MAX]
set yrange [        * : FIXED_MAX]
set yrange [FIXED_MIN :         *]
set yrange [        * :          ]

Respectively.