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internal:administration:idl [2025/07/29 09:58] – [histogram] janinternal:administration:idl [2025/11/25 14:42] (current) – [symboltypes] jan
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    1 => Plus sign (+)     1 => Plus sign (+) 
    2 => Asterisk (*)     2 => Asterisk (*) 
-   3 => Period (.) +   3 => one pixel dot (.) 
    4 => Diamond     4 => Diamond 
-   5 => Triangle 'up'+   5 => Triangle up (if symsize>0)  or down if symsize<0
    6 => Square     6 => Square 
    7 => X     7 => X 
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 ==== transparency ==== ==== transparency ====
  
-IDL does not know transparent overlays but on pixel based devices you can implement it with TVRD and TVRD.+IDL does not know transparent overlays but on pixel based devices you can implement it with TVRD and TV.
 Lets assume you want to put a bitmap BMP with size Nx, Ny at a position x0 y0 (pixels) with a tranparency factor of q_tra: Lets assume you want to put a bitmap BMP with size Nx, Ny at a position x0 y0 (pixels) with a tranparency factor of q_tra:
  
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 %%-dGraphicsAlphaBits=1%% avoids gridlines after rastering (http://www.idlcoyote.com/ps_tips/psstripes.html), \\ %%-dGraphicsAlphaBits=1%% avoids gridlines after rastering (http://www.idlcoyote.com/ps_tips/psstripes.html), \\
 %%-dEPSCrop%% crops the image at the bounding box. %%-dEPSCrop%% crops the image at the bounding box.
 +
 +You can execute gs from within IDL with the SPAWN command. As of IDL 9.x you need to prepend a ''unset LD_LIBRARY_PATH'' because IDL try to ensure its own (outdated) libraries for any spawn call:
 +  SPAWN, 'unset LD_LIBRARY_PATH; gs -dSAFER -dBATCH -dNOPAUSE -sDEVICE=png16m -r120 -dTextAlphaBits=4 -dGraphicsAlphaBits=1 -dEPSCrop -sOutputFile='+plt_name+'.png '+pl_name+'.eps', result, err_result
 +
 ==== postscript -> PDF ==== ==== postscript -> PDF ====
  
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 A one dimensional histogram is e.g. generated with A one dimensional histogram is e.g. generated with
  
-  histo = histogram( data , binsize=bin, locations = classes , /nan )+  binsize = 0.1 
 +  histo = histogram( data , binsize=binsize, locations = classes , /nan )
  
 the classes variable will contain the **lower borders** of the bins with the first bin starting at min(data). \\ the classes variable will contain the **lower borders** of the bins with the first bin starting at min(data). \\
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 or you write an own plot-histo procedure ... or you ask jan :-) ... or you write an own plot-histo procedure ... or you ask jan :-) ...
 +
 +
 +A histogram with geometric spacing, i.e. each bin is by a factor q_bin larger than the previous.\\
 +In this case data points lower or equal to zero are not allowed:
 +  q_bin = 2.0
 +  log_binsize = alog10(q_bin)
 +  histo = histogram( alog10(data[where(data gt 0)]), binsize=log_binsize, locations = log_bins, /nan )
 +  classes = 10^log_bins
 +
 +Plotting shall use then logarithmic scaling for the x-axes:
 +
 +    plot, classes , histo , psym=10, $
 +      xtitle = 'class (unit)', $
 +      ytitle = 'freq.', $
 +      /xlog
 +
  
 === 2-D histogram === === 2-D histogram ===
internal/administration/idl.1753783093.txt.gz · Last modified: by jan