irregular axis and transforms

From: James Boyle <boyle5_at_nyahnyahspammersnyahnyah>
Date: Mon, 29 Nov 2004 10:30:04 -0800

Sorry if this is a repeat to the list - but Dennis said that NCAR was
hacked and I am unsure as to the disposition of the original message:

Example 8 in of the pyngl examples shows how to plot and label a
pressure axis at non-uniform levels.

What I want to do is the same EXCEPT for irregular data. Example 8
assumes that the input data are on an evenly spaced grid.
As is very common, I have data at mandatory levels e.g. 1000., 925.,
850., 700., 600., 500., 400., 300., 250., 200., 150., 100.]
To contour these correctly I think I have to set sfYArray to these

If sfYArray is set then contour uses irregular transformations.

I want a results exactly as in example 8 BUT using sfYArray= 1000.,
925., 850., 700., 600., 500., 400., 300., 250., 200., 150.,
Thus i want the Y axis reversed and using a log Y axis.

I have tried to figure out how things work once sfYArray is set, there
appears to be complex interactions between contour, transformations
I cannot get the log to work at all and even the linear axis has the
labels equally spaced even if I follow the example.

If I set sfYCStartV and sfYCEndV I can reproduce the nice example 8
spacing and labeling but since the data are not evenly spaced the
contour plot is shown incorrectly placed in pressure space.

My bottom line is that I want to produce a plot just like Example 8,
only for irregularly spaced data as input to contour. I do not want to
interpolate the data to a regular grid - I want to see the data as it
is (within the usual havoc that contouring wreaks).

Maybe this cannot be done? I note that the meteogram example by John
Ertl, does set sfYArray and sfXArray but retains the irregular spacing
in the contour plot.

Thanks for any help


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Received on Mon Nov 29 2004 - 11:30:04 MST

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