Messages from Usenet group comp.lang.idl-pvwave, compiled by Paulo Penteado
Bruce Bowler (bbowler@bigelow.org) writes: > I have some data that I'm trying to plot where the xaxis data range is (from min and max) [0,3.19377] and the yaxis range is [-85,85]. The y axis values are fixed, the x > axis values change depending on the data set. Sometimes, the plot that results from plot,x,y,yrange=[-90,90],/ystyle has an x axis that starts at 0, sometimes it starts at - > 1 (in the particular case shown here, the range plotted is [-1,5]). I'd like to force the xaxis to start at 0 (the minimum is *never* negative) and have a "nice" upper bound > (so /xstyle doesn't work). Is there an option I'm missing? Is there a routine that will return a "nice" number (like 4, not 3.19377, or 250 if 248.9 is input), is the algorithm > that IDL uses to determine plot ranges documented anywhere? For a "nice number" axis range that always starts at 0, I'd try setting XRANGE=[0,Max(data)], with XSTYLE=0. The algorithm IDL uses is not documented anywhere I know about, but a "pretty axis" is more-or-less IDL's thing, and always when you least expect it. :-) Cheers, David -- David W. Fanning, Ph.D. Fanning Software Consulting Phone: 970-221-0438, E-mail: david@dfanning.com Coyote's Guide to IDL Programming: http://www.dfanning.com/ Toll-Free IDL Book Orders: 1-888-461-0155
David Fanning <david@dfanning.com> writes: > Bruce Bowler (bbowler@bigelow.org) writes: > >> I have some data that I'm trying to plot where the xaxis data range is (from min and max) [0,3.19377] and the yaxis range is [-85,85]. The y axis values are fixed, the x >> axis values change depending on the data set. Sometimes, the plot that results from plot,x,y,yrange=[-90,90],/ystyle has an x axis that starts at 0, sometimes it starts at - >> 1 (in the particular case shown here, the range plotted is [-1,5]). I'd like to force the xaxis to start at 0 (the minimum is *never* negative) and have a "nice" upper bound >> (so /xstyle doesn't work). Is there an option I'm missing? Is there a routine that will return a "nice" number (like 4, not 3.19377, or 250 if 248.9 is input), is the algorithm >> that IDL uses to determine plot ranges documented anywhere? > > For a "nice number" axis range that always starts at 0, > I'd try setting XRANGE=[0,Max(data)], with XSTYLE=0. > The algorithm IDL uses is not documented anywhere I know > about, but a "pretty axis" is more-or-less IDL's thing, > and always when you least expect it. :-) Tried that, same result, but I found a routine called nicenumber :-) at in the JHU-APL archive. That, in conjunction with /xstyle comes very close to what I'm looking for. Bruce