Re: y-axis log plot "Log axis requires all positive extent"

Hi Andrew,
In this case, where the axis actually is defined with linear spacing of the coordinates, this is a bug. I agree with Mary that it does not make sense. It will be fixed in 6.0.0.
 -dave

On Mar 18, 2011, at 1:45 PM, Mary Haley wrote:

> Hi Andrew,
>
> Your question got posted to "ncl-talk-owner@ucar.edu". I'm including ncl-talk@ucar.edu here.
>
> I admit I've never understood why the trYLog = True doesn't work for contour plots. Dave might have some information here.
>
> Instead of this resource, try:
>
> res@gsnYAxisIrregular2Log = True
> The way I found this resource was to go to the "tips" link off the Applications page, and then start searching on the word " log".
> I had to add the space in front of "log", because otherwise I got a bunch of "climatology" hits.
>
> I found these two examples, which both mention the same resource.
>
> Making an axis logarithmic in a contour plot
> axes_2.ncl (axes)
> conwomap_5.ncl (contours w/o maps)
>
> Hopefully this will help for future searches of information.
>
> --Mary
>
> On Mar 18, 2011, at 10:46 AM, Andrew Penny wrote:
>
>> Hi all,
>>
>> I'm attempting to create a color-filled contour plot with the y-axis in log coordinates, however,
>> nothing I try seems to work. I keep getting the error:
>>
>> warning:ContourPlotSetValues: Log axis requires all positive extent: setting trYAxisType to LinearAxis (trYLog to False)
>>
>> It looks as though this issue has been raised before, but none of the examples have
>> proven helpful. None of my coordinate arrays are equal to or less than zero. Can anyone
>> spot what I am missing? I've pasted a little dummy script below that illustrates the problem.
>>
>> Thanks in advance for your help,
>> Andy
>>
>> ;================================================
>> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl"
>> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_csm.ncl"
>>
>> ; CREATE DUMMARY DATA ARRAY "T"
>> N = 10
>> T = new((/N,N/),float)
>> do i = 0, N - 1
>> do j = 0, N - 1
>> T(j,i) = (j-N/2)*(i-N/2)
>> end do
>> end do
>>
>> wks = gsn_open_wks ("pdf", "test_log" )
>> gsn_define_colormap(wks,"rainbow")
>>
>> ; CREATE COORDINATE ARRAYS (> 0)
>> x = ispan(N,2*N-1,1)
>> y = ispan(N,2*N-1,1)
>>
>> T!0 = "vert"
>> T&vert = y
>> T!1 = "horiz"
>> T&horiz = x
>>
>> cnres = True
>> cnres@trYLog = True
>> cnres@cnFillOn = True
>> cnres@gsnSpreadColors = True
>>
>> contour = gsn_csm_contour(wks,T,cnres)
>> ;================================================
>
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Received on Fri Mar 18 14:16:14 2011