PRO AUTOHIST,V, ZX,ZY,XX,YY, NOPLOT=whatever,_EXTRA = _extra ; ;+ ; NAME: ; AUTOHIST ; ; PURPOSE: ; Draw a histogram using automatic bin-sizing. ; EXPLANATION ; AUTOHIST chooses a number of bins (initially, SQRT(2*N). If this leads ; to a histogram in which > 1/5 of the central 50% of the bins are empty, ; it decreases the number of bins and tries again. The minimum # bins is ; 5. The max=199. Called by HISTOGAUSS and HALFAGAUSS. ; ; CALLING SEQUENCE: ; AUTOHIST, Sample, XLines, Ylines, XCenters, YCenters, [/NOPLOT, ] ; ...Plotting Keywords ; INPUT: ; Sample = the vector to be histogrammed ; ; OUTPUT: ; XLINES = vector of x coordinates of the points that trace the rectangular ; histogram bins ; YLINES = vector of y coordinates. To draw the histogram plot YLINES vs ; XLINES ; XCENTERS = the x values of the bin centers ; YCENTERS = the corresponding y values ; ; OPTIONAL INPUT KEYWORDS: ; /NOPLOT If set, nothing is drawn ; ; Any plotting keywords (e.g. XTITLE) may be supplied to AUTOHIST through ; the _EXTRA facility. ; REVISION HISTORY: ; Written, H. Freudenreich, STX, 1/91 ; 1998 March 17 - Changed shading of histogram. RSH, RSTX ; V5.0 update, _EXTRA keywords W. Landsman April 2002 ; Added NOCLIP keyword for POLYFILL call C. Paxson/W. Landsman July 2003 ; Use Coyote graphics W. Landsman Feb 2011 ;- ON_ERROR,2 compile_opt idl2 if N_params() LT 1 then begin print,'Syntax - AUTOHIST, Sample, XLines, Ylines, XCenters, YCenters, [ ' print,' /NOPLOT, Plotting keywords... ]' return endif MINBIN=5 N = N_ELEMENTS(V) NB = FIX(SQRT(2.*N)) < 199 NB = NB > MINBIN X1 = MIN(V, MAX = X2) tryagain: DX = (X2-X1)/NB XX = FINDGEN(NB)*DX + DX/2. + X1 IND = (V-X1)/DX > 0 <(NB-1) ; Compute the histogram for the current binning YY = HISTOGRAM(IND,MIN=0,MAX = NB-1) ; Count the fraction of empty bins in the middle half of the histogram: X14 = (XX[NB-1]-XX[0])/4.+X1 X34 = XX[NB-1]-(XX[NB-1]-XX[0])/4. Q=WHERE( (YY EQ 0.) AND (XX GT X14) AND (XX LT X34), COUNT ) IF (COUNT GT NB/10) AND (NB GT MINBIN) THEN BEGIN ; 20% EMPTY NB = 3*NB/4 IF NB LT (2*N) THEN GOTO,tryagain ENDIF ; Fill in ZX,ZY: MB = 2*NB+2 ZX = FLTARR(MB) & ZY = FLTARR(MB) IT = INDGEN(NB)*2 + 1 ZY[IT] = YY & ZY[IT+1] = YY ZX[0] = X1 ZX[IT] = XX - DX/2. & ZX[IT+1] = XX + DX/2. ZX[MB-1] = X2 IF KEYWORD_SET(WHATEVER) THEN RETURN ; Plot, then fill, the bins: YTOP = MAX(YY[1:NB-2]) YY[0] = YY[0] < YTOP YY[NB-1] = YY[NB-1] < YTOP cgPLOT,XX,YY,XRAN=[X1-DX,X2+DX],YRAN=[0.,1.1*YTOP],PSYM=10,_EXTRA=_extra FOR J=0,NB-1 DO BEGIN IF YY[J] GT 0 THEN BEGIN A=[XX[J]-DX/2.,XX[J]+DX/2.,XX[J]+DX/2.,XX[J]-DX/2.] B=[0.,0.,YY[J],YY[J]] cgcolorFILL,A,B,orientation=45,noclip=0 ENDIF ENDFOR RETURN END