| Re: logarithmic axis lables [message #56950 is a reply to message #56945] |
Tue, 27 November 2007 14:18   |
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Paul Van Delst[1]
Messages: 1157
Registered: April 2002
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Senior Member |
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Haje Korth wrote:
> Hi,
> Is there a way to convince IDL to use axis lables like 10^-1 (10!U-1!N in
> hershey language) instead of 0.1? Plot sets this automatically to the former
> format if for very small and very large numbers, but is there a way to
> always force this format?
>
> Hints highly appreciated!
>
> Thanks,
> Haje
>
>
;+
;
; (C) Cooperative Institute for Meteorological Satellite Studies, 2000
;
; NAME:
; logticks_exp
;
; PURPOSE:
; Function to print logarithmic axis tickmarks with exponential
; output.
;
; CATEGORY:
; Graphics
;
; LANGUAGE:
; IDL v5
;
; CALLING SEQUENCE:
; PLOT, x, y, /YLOG, YICKFORMAT = 'logticks_exp'
;
; INPUTS:
; axis: the axis number. 0 for X axis, 1 for Y axis, 2 for Z axis.
; index: the tick mark index which starts at 0.
; value: the default tick mark value (a floating-point number);
;
; OUTPUTS:
; Function returns a string containing the tick mark labels.
;
; CREATION HISTORY:
; Written by: Paul van Delst, CIMSS/SSEC, 08-Nov-2000
; paul.vandelst@ssec.wisc.edu
;
;-
FUNCTION logticks_exp, axis, index, value
; Determine the base-10 exponent
exponent = LONG( ALOG10( value ) )
; Construct the tickmark string based on the exponent
tickmark = '10!E' + STRTRIM( STRING( exponent ), 2 ) + '!N'
; Return the formatted tickmark string
RETURN, tickmark
END
Use it thusly:
IDL> x=dindgen(1000)+1.0d0
IDL> y=x^2
IDL> plot, x, y, /ylog,ytickformat='logticks_exp',charsize=2
cheers,
paulv
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