;+ ; NAME: ; PARTVELVEC ; ; PURPOSE: ; Plot the velocity vectors of particles at their positions ; EXPLANATION: ; This procedure plots the velocity vectors of particles (at the ; positions of the particles). ; ; CATEGORY: ; Plotting, Two-dimensional. ; ; CALLING SEQUENCE: ; PARTVELVEC, VELX, VELY, POSX, POSY [, X, Y] ; ; INPUTS: ; VELX: An array of any dimension, containing the x-components ; of the particle velocities. ; VELY: An array of the same dimension as velx, containing the ; y-components of the particle velocities. ; POSX: An array of the same dimension as velx, containing the ; x-components of the particle positions. ; POSY: An array of the same dimension as velx, containing the ; y-components of the particle positions. ; ; OPTIONAL INPUTS: ; X: Optional abcissae values. X must be a vector. ; Y: Optional ordinate values. Y must be a vector. If only X ; is specified, then Y is taken equal to be equal to X. ; ; OPTIONAL INPUT KEYWORD PARAMETERS: ; FRACTION: The fraction of the vectors to plot. They are ; taken at random from the complete sample. Default is ; FRACTION = 1.0, use all vectors ; ; LENGTH: The maximum vectorlength relative to the plot data ; window. Default = 0.08 ; ; COLOR: Color for the vectors, axes and titles by string name or ; number (see cgCOLOR). Note that if VECCOLORS is ; supplied, then the COLOR keyword still specifies the ; color of the axes and title. Default = 'Opposite' ; ; OVER: Plot over the previous plot ; ; VECCOLORS: The vector colors. Must be either a scalar, or ; a vector (nmeric or string) the same size as VELX. ; Set to COLOR by default. ; WINDOW - Set this keyword to plot to a resizeable graphics window ; ; Plot All other keywords available to cgPlot (e.g. AXISCOLOR, ; Keywords: LINESTYLE, XRANGE) are available (via _EXTRA) ; ; OUTPUTS: ; This procedure plots the velocity vectors (VELX,VELY) at the ; positions of the particles, (POSX,POSY). If X and Y are not ; specified, then the size of the plot is such that all vectors ; just fit within in the plot data window. ; ; SIDE EFFECTS: ; Plotting on the current device is performed. ; ; EXAMPLE: ; Generate some particle positions and velocities. ; ; POSX=RANDOMU(seed,200) ; POSY=RANDOMU(seed,200) ; VELX=RANDOMU(seed,200)-0.5 ; VELY=RANDOMU(seed,200)-0.5 ; ; Plot the particle velocities. ; ; PARTVELVEC, VELX, VELY, POSX, POSY ; ; Example using vector colors. ; ; POSX=RANDOMU(seed,200) ; POSY=RANDOMU(seed,200) ; VELX=RANDOMU(seed,200)-0.5 ; VELY=RANDOMU(seed,200)-0.5 ; magnitude = SQRT(velx^2 + vely^2) ; LOADCT, 5, NCOLORS=254, BOTTOM=1 ; Load vector colors ; colors = BytScl(magnitude, Top=254) + 1B ; PARTVELVEC, VELX, VELY, POSX, POSY, COLOR='green', VECCOLORS=colors ; ; MODIFICATION HISTORY: ; Written by: Joop Schaye (jschaye@astro.rug.nl), Sep 1996. ; Added /OVER keyword Theo Brauers (th.brauers@fz-juelich.de) Jul 2002 ; Added VECCOLORS keyword. David Fanning (david@dfanning.com) March, 2005 ; Incorporate the Coyote Graphics (cg) plot programs WL January 2011 ;- PRO partvelvec,velx,vely,posx,posy,x,y, OVER = over, VECCOLORS=vecColors, $ FRACTION=fraction,LENGTH=length,COLOR=color,WINDOW=window, $ _EXTRA=extra ;--------------------------------------------- ; Various settings, modify these to customize ;--------------------------------------------- c = {customize, $ length: 0.08, $ ; Maximum vector length relative to plot region. (*) lengtharrow: 0.3, $ ; Length of arrowhead legs relative to vectorlength. angle: 22.5 } ; 1/2 times the angle between the arrowhead legs. ; (*) Not used if keyword LENGTH is present ;--------------------- ; Some error handling ;--------------------- on_error,2 ; Return to caller if an error occurs. nparams=n_params() IF nparams NE 4 THEN BEGIN IF (nparams NE 5 AND nparams NE 6) THEN BEGIN message,'Wrong number of parameters!',/continue message,'Syntax: PARTVELVEC, VELX, VELY, POSX, POSY [, X, Y]', $ /noname,/noprefix ENDIF IF nparams EQ 5 THEN y=x sizex = size(x) sizey = size(y) IF (sizex[0] NE 1 || sizey[0] NE 1) THEN $ message,'X and Y must be vectors!' ENDIF sizevelx = size(velx) sizevely = size(vely) sizeposx = size(posx) sizeposy = size(posy) IF (total(sizevelx[0:sizevelx[0]]-sizevely[0:sizevelx[0]]) NE 0 $ || total(sizevelx[0:sizevelx[0]]-sizeposx[0:sizevelx[0]]) NE 0 $ || total(sizevelx[0:sizevelx[0]]-sizeposy[0:sizevelx[0]]) NE 0) THEN $ message,'All arguments must have the same dimension and size!' IF n_elements(fraction) GT 0 THEN $ IF (fraction LT 0.0 || fraction GT 1.0) THEN $ message,'Fraction has to be between 0.0 and 1.0.' ;-------------- ; Prepare plot ;-------------- nvecs = n_elements(velx) ; Number of particles. vel = sqrt(velx^2+vely^2) ; Total velocity. maxvel = max(vel) ; Maximum velocity. ; Compute maximum length of vectors. IF n_elements(length) LE 0 THEN length=c.length minposx = min(posx) maxposx = max(posx) minposy = min(posy) maxposy = max(posy) length = length*((maxposx-minposx) > (maxposy-minposy)) ; Convert velocities. vx = length*velx/maxvel vy = length*vely/maxvel vel = length*temporary(vel)/maxvel ; Make sure no vectors extend beyond the plot data window. x1 = posx+vx ; End of vector. y1 = posy+vy IF nparams EQ 4 THEN BEGIN minposx = min(x1)maxposx minposy = min(y1)maxposy ENDIF angle = c.angle*!dtor ; Convert from degrees to radians. sinangle = sin(angle) ; Need these. cosangle = cos(angle) ;----------- ; Plot axes ;----------- if N_elements(color) EQ 0 then color = cgcolor('opposite') IF n_elements(veccolors) EQ 0 THEN BEGIN veccolors = Replicate(cgcolor('opposite'), nvecs) ENDIF ELSE BEGIN nvc = N_Elements(veccolors) CASE nvc OF 1: veccolors = Replicate(veccolors, nvecs) nvecs: ELSE: Message, 'Vector color array VECCOLORS must be same size as VELX.' ENDCASE ENDELSE IF n_elements(over) EQ 0 THEN BEGIN IF nparams EQ 4 THEN $ cgPlot,[minposx,maxposx],[minposy,maxposy], axiscolor=color,$ /nodata,/xstyle,/ystyle,COLOR=color,window=window,_EXTRA=extra $ ELSE cgPlot,x,y,/nodata,/xstyle,/ystyle,COLOR=color,window=window,_EXTRA=extra ENDIF if keyword_set(window) then cgcontrol,execute=0 ;-------------- ; Plot vectors ;-------------- IF (n_elements(fraction) GT 0) && (fraction NE 1.0) THEN BEGIN nrgood=long(fraction*nvecs) ; # of vectors to plot. IF nrgood EQ 0 THEN return ; Compute indices of vectors to plot. I use two lines to get more ; random "random numbers". good=long(randomu(seed,nrgood+1)*(nvecs-1.0)) good=good[1:*] vx = temporary(vx[good]) vy = temporary(vy[good]) px = posx[good] ; Can't use temporary if we wan't to keep the data. py = posy[good] x1 = temporary(x1[good]) y1 = temporary(y1[good]) nvecs=nrgood ENDIF ELSE BEGIN px=posx py=posy ENDELSE FOR i=0l,nvecs-1l DO BEGIN ; Loop over particles. ; Note that we cannot put the next three lines outside the loop, ; because we want the arrow size to be relative to the vector length. r = c.lengtharrow*vel[i] ; Length of arrow head. rsin = r*sinangle rcos = r*cosangle ; Draw basis, arrow leg, same arrow leg, other arrow leg. ; One arrow leg is drawn twice, because we need to return to the end ; of the vector to draw the other leg. cgPlots,[px[i],x1[i],x1[i]-(vx[i]*rcos+vy[i]*rsin)/vel[i], $ x1[i],x1[i]-(vx[i]*rcos-vy[i]*rsin)/vel[i]], $ [py[i],y1[i],y1[i]-(vy[i]*rcos-vx[i]*rsin)/vel[i], $ y1[i],y1[i]-(vy[i]*rcos+vx[i]*rsin)/vel[i]],COLOR=veccolors[i],$ ADDCMD = window ENDFOR if keyword_set(window) then cgcontrol,execute=1 return END ; End of procedure PARTVELVEC.