| PSYM=10 problem [message #17831] |
Tue, 16 November 1999 00:00 |
Laurent Chardon
Messages: 8
Registered: June 1999
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Junior Member |
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Is there a good reason why the first bin plotted by the plot/PSYM=10
combination is half the size of all the others? Can I get around this
behaviour? I want all the bins to be of equal size.
Thanks for your help.
Laurent
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| Re: PSYM=10 problem [message #17920 is a reply to message #17831] |
Tue, 16 November 1999 00:00  |
Craig Markwardt
Messages: 1869
Registered: November 1996
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Senior Member |
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Liam Gumley <Liam.Gumley@ssec.wisc.edu> writes:
>
> Laurent Chardon wrote:
>> Is there a good reason why the first bin plotted by the plot/PSYM=10
>> combination is half the size of all the others? Can I get around this
>> behaviour? I want all the bins to be of equal size.
>
> A few months ago in this newsgroup, David Fanning convinced me that
> PSYM=10 would never give an accurate representation of a histogram, and
> that the only way to do it right is to plot the histogram yourself. As
> you've noted, the problem is getting the edges of the bins in the right
> position. I came up with the following procedure which I believe
> computes and plots a 'correct' histogram (let me know if I'm wrong!):
Thanks to Liam for his sample program. I also have a histogram
plotter called PLOTBIN. While it leaves the histogramming to you
(unlike Liam's), it does a pretty good job of actually plotting the
right thing.
It is distinguished by the ability to plot bins of different widths,
which is especially nice on log-log graphs. You can specify a single
binsize with the WIDTH keyword, or give a vector of widths, one for
each bin.
Craig
http://cow.physics.wisc.edu/~craigm/idl/idl.html
--
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Craig B. Markwardt, Ph.D. EMAIL: craigmnet@cow.physics.wisc.edu
Astrophysics, IDL, Finance, Derivatives | Remove "net" for better response
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| Re: PSYM=10 problem [message #17924 is a reply to message #17831] |
Tue, 16 November 1999 00:00 |
davidf
Messages: 2866
Registered: September 1996
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Senior Member |
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Liam Gumley (Liam.Gumley@ssec.wisc.edu) writes:
> A few months ago in this newsgroup, David Fanning convinced me that
> PSYM=10 would never give an accurate representation of a histogram, and
> that the only way to do it right is to plot the histogram yourself.
Indeed, if this is true, you must have been the *only* one
I convinced, Liam, if my mail is any indication. (I did
get a nice e-mail from a chap the other day who admitted
that after thinking I was feeding him a crock of bull for
over three months the light finally went on and he realized
I was right. :-)
In any case, I'm right, and I think this solution you
offer here may be a good one. I intend to approach it
in a slightly different way when I get the chance.
(I was looking at my notes just the other day.) But
there are only about, oh, 100 things in line first. :-(
Cheers,
David
--
David Fanning, Ph.D.
Fanning Software Consulting
Phone: 970-221-0438 E-Mail: davidf@dfanning.com
Coyote's Guide to IDL Programming: http://www.dfanning.com/
Toll-Free IDL Book Orders: 1-888-461-0155
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| Re: PSYM=10 problem [message #17925 is a reply to message #17831] |
Tue, 16 November 1999 00:00 |
Laurent Chardon
Messages: 8
Registered: June 1999
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Junior Member |
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Thank you Steve and Liam for your answers.
Laurent
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Laurent Chardon <chardons@NOT_THISsprint.ca (Remove NOT_THIS to reply)>
wrote in message news:iSgY3.39227$1v5.925927@newscontent-01.sprint.ca...
> Is there a good reason why the first bin plotted by the plot/PSYM=10
> combination is half the size of all the others? Can I get around this
> behaviour? I want all the bins to be of equal size.
>
> Thanks for your help.
>
> Laurent
>
> --
>
> Remove NOT_THIS in the email address to reply.
>
>
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