;+ ; NAME: ; partvelvec ; ; PURPOSE: ; 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: The color for the vectors, axes and titles. ; Default=!P.COLOR ; ; OVER: Plot over the previous plot ; ; Plot All other keywords available to PLOT are also used ; Keywords: by this procedure. ; ; 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 ; ; MODIFICATION HISTORY: ; Written by: Joop Schaye (jschaye@astro.rug.nl), Sep 1996. ; Modified: Theo Brauers (th.brauers@fz-juelich.de) Oct. 1997 ; use with maps, incl. debug ;- PRO partvelvec,velx,vely,posx,posy,x,y, OVER=over, $ FRACTION=fraction,LENGTH=length,COLOR=color,_EXTRA=extra debug, '1.10 T.B. 1997-OCT-20' ;--------------------------------------------- ; 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 OR 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 $ OR total(sizevelx(0:sizevelx(0))-sizeposx(0:sizevelx(0))) NE 0 $ OR 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 OR 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=!p.color IF n_elements(over) EQ 0 THEN BEGIN IF nparams EQ 4 THEN $ plot,[minposx,maxposx],[minposy,maxposy], $ /nodata,/xstyle,/ystyle,COLOR=color,_EXTRA=extra $ ELSE plot,x,y,/nodata,/xstyle,/ystyle,COLOR=color,_EXTRA=extra ENDIF ;-------------- ; Plot vectors ;-------------- IF n_elements(fraction) GT 0 THEN BEGIN IF fraction EQ 1.0 THEN GOTO,plotall 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 plotall: 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. plots,[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=color ENDFOR END ; End of procedure PARTVELVEC.