source: trunk/PLOTS/DESSINE/bar_plot.pro @ 2

; $Id$
;
; Copyright (c) 1990-2000, Research Systems, Inc.  All rights reserved.
;       Unauthorized reproduction prohibited.
;

pro bar_plot,values,baselines=baselines,colors=colors,barnames=barnames, $
          title=title,xtitle=xtitle,ytitle=ytitle,baserange=baserange, $
          barwidth=barwidth,barspace=barspace,baroffset=baroffset, $
          outline=outline,overplot=overplot,background=background, $
          rotate=rotate, _EXTRA = ex
;+
; NAME:
;       BAR_PLOT
;
; PURPOSE:
;       Create a bar graph, or overplot on an existing one.
;
; CATEGORY:
;       Graphics.
;
; CALLING SEQUENCE:
;       BAR_PLOT, Values
;
; INPUTS:
;       Values: A vector containing the values to be represented by the bars.
;               Each element in VALUES corresponds to a single bar in the
;               output.
;
; KEYWORD PARAMETERS:
;   BASELINES:  A vector, the same size as VALUES, that contains the
;               base value associated with each bar.  If not specified,
;               a base value of zero is used for all bars.
;
;      COLORS:  A vector, the same size as VALUES, containing the color index
;               to be used for each bar.  If not specified, the colors are
;               selected based on spacing the color indices as widely as
;               possible within the available colors (specified by D.N_COLORS).
;
;    BARNAMES:  A string array, containing one string label per bar.
;               If the bars are vertical, the labels are placed beneath
;               them.  If horizontal (rotated) bars are specified, the labels
;               are placed to the left of the bars.
;
;       TITLE:  A string containing the main title to for the bar plot.
;
;       XTITLE: A string containing the title for the X axis.
;
;       YTITLE: A string containing the title for the Y axis.
;
;   BASERANGE:  A floating-point scalar in the range 0.0 to 1.0, that
;               determines the fraction of the total available plotting area
;               (in the direction perpendicular to the bars) to be used.
;               If not specified, the full available area is used.
;
;    BARWIDTH:  A floating-point value that specifies the width of the bars
;               in units of "nominal bar width".  The nominal bar width is
;               computed so that all the bars (and the space between them,
;               set by default to 20% of the width of the bars) will fill the
;               available space (optionally controlled with the BASERANGE
;               keyword).
;
;    BARSPACE:  A scalar that specifies, in units of "nominal bar width",
;               the spacing between bars.  For example, if BARSPACE is 1.0,
;               then all bars will have one bar-width of space between them.
;               If not specified, the bars are spaced apart by 20% of the bar
;               width.
;
;   BAROFFSET:  A scalar that specifies the offset to be applied to the
;               first bar, in units of "nominal bar width".  This keyword
;               allows, for example, different groups of bars to be overplotted
;               on the same graph.  If not specified, the default offset is
;               equal to BARSPACE.
;
;     OUTLINE:  If set, this keyword specifies that an outline should be
;               drawn around each bar.
;
;    OVERPLOT:  If set, this keyword specifies that the bar plot should be
;               overplotted on an existing graph.
;
;  BACKGROUND:  A scalar that specifies the color index to be used for
;               the background color.  By default, the normal IDL background
;               color is used.
;
;       ROTATE: If set, this keyword indicates that horizontal rather than
;               vertical bars should be drawn.  The bases of horizontal bars
;               are on the left, "Y" axis and the bars extend to the right.
;
; OUTPUTS:
;       A bar plot is created, or an existing one is overplotted.
;
; EXAMPLE:
;       By using the overplotting capability, it is relatively easy to create
;       stacked bar charts, or different groups of bars on the same graph.
;
;       For example, if ARRAY is a two-dimensional array of 5 columns and 8
;       rows, it is natural to make a plot with 5 bars, each of which is a
;       "stacked" composite of 8 sections.  First, create a 2D COLORS array,
;       equal in size to ARRAY, that has identical color index values across
;       each row to ensure that the same item is represented by the same color
;       in all bars.
;
;       With ARRAYS and COLORS defined, the following code fragment
;       illustrates the creation of stacked bars (note that the number of rows
;       and columns is arbitrary):
;
;       !Y.RANGE = [0,ymax] ; Scale range to accommodate the total bar lengths.
;       BASE = INTARR(NROWS)
;       FOR I = 0, NROWS-1 DO BEGIN
;          BAR_PLOT, ARRAY(*,I), COLORS=COLORS(*,I), BASELINES=BASE, $
;                    BARWIDTH=0.75, BARSPACE=0.25, OVER=(I GT 0)
;          BASE = BASE + ARRAY(*,I)
;       ENDFOR
;
;       To plot each row of ARRAY as a clustered group of bars within the same
;       graph, use the BASERANGE keyword to restrict the available plotting
;       region for each set of bars.  The sample code fragment below
;       illustrates this method:
;
;       FOR I = 0, NROWS-1 DO $
;          BAR_PLOT, ARRAY(*,I), COLORS=COLORVECT, BARWIDTH=0.8,BARSPACE=0.2, $
;            BAROFFSET=I*((1.0+BARSPACE)*NCOLS), OVER=(I GT 0), BASERANGE=0.19
;
;       where NCOLS is the number of columns in ARRAY, and COLORVECT is a
;       vector containing the color indices to be used for each group of
;       bars.  (In this example, each group uses the same set of colors, but
;       this could easily be changed.)
;
; MODIFICATION HISTORY:
;       August 1990, T.J. Armitage, RSI, initial programming.  Replacement
;       for PLOTBAR and OPLOTBAR routines written by William Thompson.
;
;       September 1990, Steve Richards, RSI, changed defaults to improve the
;       appearance of the bar plots in the default mode. Included
;       spacing the bars slightly.
;-
if (n_params(d) eq 0) then begin  ;Print call & return if no parameters
  print,'bar_test,values,baselines=baselines,colors=colors,barnames=barnames,$'
  print,' title=title,xtitle=xtitle,ytitle=ytitle,baserange=baserange, $'
  print,' barwidth=barwidth,barspace=barspace,baroffset=baroffset, $'
  print,' outline=outline,overplot=overplot,background=background, $'
  print,' rotate=rotate'
  return
endif

nbars=n_elements(values)                ; Determine number of bars
; Baselines (bars extend from baselines through values); default=0
if not(keyword_set(baselines)) then baselines=intarr(nbars)
; Default colors spaced evenly in current color table
if not(keyword_set(colors)) then $
   colors=fix((!d.n_colors/float(nbars))*(indgen(nbars)+0.5))
; Labels for the individual bars; none by default
if not(keyword_set(barnames)) then barnames=strarr(nbars)+' '
; Main title
if not(keyword_set(title)) then title=''
; Centered title under X-axis
if not(keyword_set(xtitle)) then xtitle=''
; Title for Y-axis
if not(keyword_set(ytitle)) then ytitle=''
; Fraction (0-1) of full X range to use
if not(keyword_set(baserange)) then baserange=1.0
; Space betw. bars, taken from nominal bar widths; default is none
If not(keyword_set(barspace)) then barspace=0.2
; Bar width scaling factor, relative to nominal
if not(keyword_set(barwidth)) then barwidth=1.0 - barspace - barspace / nbars
; Initial X offset, in scaled bar widths; default is none
if not(keyword_set(baroffset)) then baroffset=barspace/barwidth
; Outline of bars; default is none
outline = keyword_set(outline)
; Overplot (do not erase the existing display); default is to create new plot
overplot = keyword_set(overplot)
; Background color index; defaults to 0 (usually black) if not specified
if not(keyword_set(background)) then background=0
; Rotate (make horizontal bars); default is vertical bars
rotate = keyword_set(rotate)

mnB = MIN(baselines, MAX=mxB, /NAN)
mnV = MIN(values, MAX=mxV, /NAN)
range=[mnB < mnV, $    ;Minimum of bases & values
                mxB > mxV]      ;Maximum of bases & values

if (rotate) then begin                             ;Horizontal bars
   if (!x.range[0] eq 0) and (!x.range[1] eq 0) $  ;Determine range for X-axis
      then xrange=range $
      else xrange=!x.range                         ;Or, use range specified
   if (!y.range[0] eq 0) and (!y.range[1] eq 0) $  ;Plot will calculate
      then $                                       ; defaults for X, but not
        yrange = [0, n_elements(values)] $         ; for Ys, so fill in here.
      else $
        yrange=!y.range                            ;Axis perpend. to bars
   yticks=1                                        ;Suppress ticks in plot
   ytickname=strarr(2)+' '
   xticks=0
   xtickname=strarr(1)+''
endif else begin                                   ;Vertical bars
   if (!y.range[0] eq 0) and (!y.range[1] eq 0) $  ;Determine range for Y-axis
      then yrange=range $
      else yrange=!y.range                         ;Or, use range specified
   xrange=!x.range                                 ;Axis perpend. to bars
   xticks=1                                        ;Suppress ticks in plot
   xtickname=strarr(2)+' '
   yticks=0
   ytickname=strarr(1)+''
endelse
if (overplot eq 0) then $                          ;Create new plot, no data
plot,[values],/nodata,title=title,xtitle=xtitle,ytitle=ytitle, $
   noerase=overplot,xrange=xrange,yrange=yrange,xticks=xticks, $
   xtickname=xtickname,yticks=yticks,ytickname=ytickname, $
   xstyle=1,ystyle=1,/data,background=background, _EXTRA = ex
if (rotate) then begin                             ;Horizontal bars
   base_win=!y.window                              ;Window range in Y
   scal_fact=!x.s                                  ;Scaling factors
   tick_scal_fact=!y.s                             ;Tick scaling factors
endif else begin                                   ;Vertical bars
   base_win=!x.window                              ;Window range in X
   scal_fact=!y.s                                  ;Scaling factors
   tick_scal_fact=!x.s                             ;Tick scaling factors
endelse
winrange=baserange*(base_win[1]-base_win[0])       ;Normal. window range
barsize=barwidth*winrange/nbars                    ;Normal. bar width
winoffset=base_win[0]+(baroffset*barsize)          ;Normal. first offset
bases=scal_fact[0]+(scal_fact[1]*baselines)        ;Baselines, in normal coor.
normal=scal_fact[0]+(scal_fact[1]*values)          ;Values, in normal coor.
barstart=indgen(nbars)*(barsize+barspace*(winrange/nbars)) ;Coor. at left edges
tickv=winoffset+barstart+(0.5*barsize)             ;Tick coor. (centered)
for i=0,nbars-1 do begin                           ;Draw the bars
   width=winoffset+[barstart[i],barstart[i], $     ;Compute bar width
     (barstart[i]+barsize),(barstart[i]+barsize)]
   length=[bases[i],normal[i],normal[i],bases[i]]  ;Compute bar length
   if (rotate) then begin                          ;Horizontal bars
      x=length                                     ;X-axis is "length" axis
      y=width                                      ;Y-axis is "width" axis
   endif else begin                                ;Vertical bars
      x=width                                      ;X-axis is "width" axis
      y=length                                     ;Y-axis is "length" axis
   endelse
   polyfill,x,y,color=colors[i],/normal            ;Polyfill with color
   if (outline) then plots,x,y,/normal             ;Outline using !p.color
endfor

tickv=(tickv-tick_scal_fact[0])/tick_scal_fact[1]  ;Locations of the ticks
if (rotate) then $                                 ;Label the bars (Y-axis)
  axis,yaxis=0,ystyle=1,yticks=(nbars-1),ytickv=tickv,ytickname=barnames, $
  yticklen=0.0 $
else $                                             ;Label the bars (X-axis)
  axis,xaxis=0,xstyle=1,xticks=(nbars-1),xtickv=tickv,xtickname=barnames, $
  xticklen=0.0
return
end