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- function nice_contourlevels, data, nlevels=nlevels
- ;+----------------------------------------------------------------------------------------
- ; nice_contourlevels.pro
- ;
- ; Select nice contour levels based on the data input and the number of levels
- ;
- ; Author: D. J. Lea - Feb 2008
- ;
- ;+----------------------------------------------------------------------------------------
- if (n_elements(nlevels) eq 0) then nlevels=15
- mx=max(data)
- mn=min(data)
- ; use this to select colors to plot and labels
- clevels=findgen(nlevels)/nlevels*(mx-mn)+mn
- ocint=1./nlevels*(mx-mn)
- print,'ocint ',ocint
- ; contour interval at 2 sig figs
- ;digits=2
- ;p10 = floor(alog10(abs(ocint)))
- ;expo = 10.0d^(digits -1 - p10)
- ;cint = long(ocint*expo)/expo
- ;print,'cint ',cint
- ;does it end in 5 or 0?
- digits=1
- p10 = floor(alog10(abs(ocint)))
- expo = 10.0d^(digits -1 - p10)
- cint = long(ocint*expo)/expo
- print,'cint ',cint
- if (mx ne mn) then begin
- mxfix=fix(mx/cint)*cint
- mnfix=fix(mn/cint)*cint
- print, mx, mxfix
- print, mn, mnfix
- ; nice contour values
- ;calculate new nlevels
- nlevels=fix((mxfix-mnfix)/cint+1)
- ;print,nlevels
- if (nlevels gt 0) then begin
- clevels=findgen(nlevels)*cint+mnfix
- endif else begin
- clevels=mnfix
- endelse
- endif else begin
- clevels=mn
- endelse
- return, clevels
- end
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