On Fri 06 Feb 2026 at 23:30:14 (+0000), David wrote: > On Fri, 6 Feb 2026 at 16:00, David Wright <[email protected]> wrote: > > On Fri 06 Feb 2026 at 14:27:26 (+0000), Chris Green wrote: [ … ] > > > No, it doesn't really address the issue, or at least I don't think it > > > does, I may be misunderstanding though. > > > > I have more X values than will fit across the screen as discrete points. > > > > So, for a day's results, I have 1440 x values, going from 0 to 1339 > > > (minutes in a day). One of the sets of y values will simply be a > > > battery voltage, probably in the range 10v to 15v. I want to have a > > > plot which shows how the voltage varies over the 24 hours (1440 > > > minutes) of the day with, say, the hour of the day shown on the x-axis. > > > I've not used gnuplot before. > > Me neither! :)
I thought I'd try something a bit more random. So I typed: $ for j in $(seq 10 0.0005 15); do printf '%s\t%s\n' "$RANDOM" "$j"; done | sort -n > values > > I then cut and pasted the exact gnuplot lines above, and a graph > > popped up on the screen, showing a … mass of blue, with white circles outlining the dots (your pointintervalbox, David, was a clever touch), showing … > > a "battery" … voltage affected by a bad connection. There were 10001 points "squeezed" into the X-axis with no difficulty at all. I'd already discovered that a right-click and left-click sequence would magnify sections of the graph, so I could check that it was all plotted correctly. I have some old day-long files of temperature and battery charge meansured every three seconds, but I haven't used them as test data because I'd need to read up about using their HH:MM:SS timestamps for the X-axis. > > Isn't that what you want? … when you have already collected your data. > I found a similar question [1] on stackoverflow, where the solution seems > to be using a gnuplot 'filter' [2], possibly a 'bins' filter [3]. > > [1] > https://stackoverflow.com/questions/22839796/reduce-datapoints-when-using-logscale-in-gnuplot > [2] http://www.gnuplot.info/docs/loc8198.html > [3] http://www.gnuplot.info/docs/loc8212.html Because the OP gave a linear example, I haven't bothered with any data transformations at all. The HTML files in gnuplot-doc were well organised, so I figured out what the two-letter abbreviations were doing. One or two (like "with lp ls 1") look non-unique, so I need to play with changing them, and I haven't yet come across a table for changing from blue dots by setting a value other than that "1". Sometime I'll take a look at rrdtool and try realtime plotting. Cheers, David.
