I wrote this as a "fix" to velovect. It allows one to place
vectors over a pre-drawn plot, like a map background.
Please let me know if it works for you.
There is a nice text widget at the top which
provides usage information.
;This "front end" procedure is a help tool for velovect.
pro vec_help
base = widget_base(title='VEC_HELP', /row)
list = widget_text(base, xsize=85, ysize=20 ,scroll=1, $
font='-adobe-helvetica-medium-r-normal--14-140-75-75-p-77-is o8859-1', $
value=[$
'=========================================================== ============',$
' >>>> MAP_VEC HELP MENU
<<<<', $
' ', $
' The map_vec procedure plots vectors within an existing plot
space.', $
' Usually a map is produced, then vectors are overlayed using
velovect.', $
' ', $
'----------------------------------------------------------- ------------',$
'USAGE: map_vec, u, v, x, y, missing=missing, length=length, maxvec=maxvec,
round=round, $', $
' dots=dots, color=color, everyx=everyx, everyy=everyy,
arrowsize=arrowsize, $', $
' limit=limit, refvec=refvec, refunit=refunit,
refposx=refposx, $',$
' refposy=refposy, reflabely=reflabely, charsize=charsize,
help=help', $
'=========================================================== ============',$
' ', $
'PARAMETERS:', $
' u,v.............. 2-D data arrays specifying the zonal and meridional
velocity components.', $
' x,y.............. Meridional and zonal location vectors (longitude,
latitude).', $
' ', $
'KEYWORDS:', $
' missing.......... Do not plot vectors with a magnitude greater or equal to
this value.', $
' length........... Length factor. The default of 1.0 makes the longest
vector the', $
' length of one grid cell.', $
' maxvec........... Maximum vector magnitude for scaling. Default is
computed', $
' round............ Round computed maxvec so it is divisible by 5.', $
' dots............. After setting dots to 1, a dot is placed at missing data
points.', $
' color............ Color index for drawing vectors. Default is zero.', $
' everyx........... Plot every 2nd, 3rd, 4th... vector in the x direction.
Default is 1.', $
' everyy........... Plot every 2nd, 3rd, 4th... vector in the y direction.
Default is 1.', $
' arrowsize........ Factor by which default arrowsize is multiplied.', $
' limit............ vector containing [latmin, lonmin, latmx, lonmax] for
plotting area.', $
' ', $
' refvec........... After setting refvec to 1, a "max vector magnitude"
arrow appears on the plot.',$
" refunit.......... String variable containing unit of the reference vector.
Default is 'm s!U-1!n.'",$
' refposx.......... Ending x position (in data coords.) for drawing refvec.
Default is computed.', $
' refposy.......... Y position (in data coords.) for drawing refvec.
Default is computed.', $
' reflabely........ Y position (in data coords.) for drawing label beneath
refvec. Default is computed.', $
' charsize......... Character size for reference vector label. Default is
.88', $
' help............. Bring up this help menu.', $
'........................................................... ....................
.....................'+$
'........................................................... ....................
.....................'+$
'..........................',$
' ', $
' EXAMPLE: Plotting global taux, tauy data.', $
" taux = rz('/data/obs/nmc/stress/taux_9_90', xloc=x, yloc=y)", $
" tauy = rz('/data/obs/nmc/stress/tauy_9_90')", $
' gplot, taux, x, y, /nodata ... or ... map_set, 0, 180,
/cont, /cyl', $
' ', $
' map_vec, taux, tauy, x, y, missing=999., everyx=2, everyy=1,
length=5, /dots, $', $
" /refvec, refunit='dynes cm !e-2!n', refposx=340.,
refposy=-100., $", $
' reflabely=-106.', $
' ' ])
widget_control, /realize, base
end
pro map_vec, u, v, x, y, missing=missing, length=length, maxvec=maxvec,
round=round, $
dots=dots, color=color, everyx=everyx, everyy=everyy,
arrowsize=arrowsize, $
limit=limit, refvec=refvec, refunit=refunit, refposx=refposx,
refposy=refposy, $
reflabely=reflabely, charsize=charsize, help=help
;
; NAME:
; MAP_VEC
;
;
; PURPOSE:
; Produce a two-dimensional velocity field plot.
;
; A directed arrow is drawn at each point showing the direction and
; magnitude of the field.
;
;
; CATEGORY:
; Plotting, two-dimensional.
;
;
; CALLING SEQUENCE:
; MAP_VEC, U, V, X, Y
;
;
; INPUTS:
; U: The X component of the two-dimensional field.
; U must be a two-dimensional array.
;
; V: The Y component of the two dimensional field. Y must have
; the same dimensions as X. The vector at point (i,j) has a
; magnitude of:
;
; SQRT ( U(i,j)^2 + V(i,j)^2 )
;
; and a direction of:
;
; ATAN2 ( V(i,j), U(i,j) )
;
;
; OPTIONAL INPUT PARAMETERS:
; X: Optional abcissae values. X must be a vector with a length
; equal to the first dimension of U and V.
;
; Y: Optional ordinate values. Y must be a vector with a length
; equal to the first dimension of U and V.
;
;
; KEYWORD INPUT PARAMETERS:
; MISSING: Missing data value. Vectors with a LENGTH greater
; than MISSING are ignored.
;
; LENGTH: Length factor. The default of 1.0 makes the longest (U,V)
; vector the length of a cell.
;
; DOTS: Set this keyword to 1 to place a dot at each missing point.
; Set this keyword to 0 or omit it to draw nothing for missing
; points. Has effect only if MISSING is specified.
;
; COLOR: The color index used for the arrows.
;
; EVERY: Plot every ____ vector. Default is 1.
;
; REFARROW: Plot a maximum vector magnitude. Default is 0 (NO).
;
; REFUNIT: Unit of max arrow. Default is m s!e-1!n (i.e., m/s)
;
; REFPOSX: X starting position of maxxarrow. Default is computed.
;
; REFPOSY: Y position of maxxarrow. Default is computed.
;
; REFLABELY: Y position of refveclabel. Default is computed.
;
;
; OUTPUTS:
; None.
;
;
; COMMON BLOCKS:
; None.
;
;
; SIDE EFFECTS:
; Plotting on the selected device is performed.
;
;
; RESTRICTIONS:
; None.
;
;
; PROCEDURE:
; Straightforward. The system variables !XTITLE, !YTITLE and
; !MTITLE can be set to title the axes.
;
;
; MODIFICATION HISTORY:
; DMS, RSI, Oct., 1983.
;
; For Sun, DMS, RSI, April, 1989.
;
; Added TITLE, Oct, 1990.
;
; Added POSITION, NOERASE, COLOR, Feb 91, RES.
;
; Added all keywords past color. June 1993, Andrew F. Loughe
; Draw to current plot area (usually a map).
on_error, 2 ;Return to caller if an error occurs
help = keyword_set(help)
if (help eq 1 or n_params() eq 0) then begin
vec_help
message, 'Stopped for help in map_vec.pro'
endif
s = size(u)
t = size(v)
; Check size of input arrays.
if n_params(1) lt 4 then $
message, 'Must specify u, v, x, y'
if s(0) ne 2 then begin
baduv: message, 'U and V parameters must be 2D and same size.'
endif
if total(abs(s(0:2)-t(0:2))) ne 0 then goto, baduv
if (n_elements(x) ne s(1) or n_elements(y) ne s(2)) then $
message, 'X and Y arrays have incorrect size.'
; Set some default values.
if n_elements(missing) le 0 then missing = 1.0e10
if n_elements(length) le 0 then length = 1.0
if n_elements(maxvec) le 0 then maxvec = -1.
if n_elements(round) le 0 then round = 0
if n_elements(everyx) le 0 then everyx = 1
if n_elements(everyy) le 0 then everyy = 1
if n_elements(arrowsize) le 0 then arrowsize = 1.
if n_elements(limit) le 0 then limit = [-100.,-10000.,100.,10000.]
if n_elements(title) le 0 then title = ''
if n_elements(charsize) le 0 then charsize = .88
if n_elements(color) le 0 then color = 0
latmin = limit(0) ;Get geographical limits
lonmin = limit(1) ;for plotting the data
latmax = limit(2)
lonmax = limit(3)
mag = sqrt(u^2 + v^2) ;Get magnitude of all vectors
; Get subscripts of good and bad elements.
; good = those points where vector magnitude is less than missing value.
; bad = those points where vector magnitude is greater or equal to missing value.
nbad = 0 ;# of missing points
if n_elements(missing) gt 0 then begin
good = where(mag lt missing)
if keyword_set(dots) then bad = where(mag ge missing, nbad)
endif else begin
good = lindgen(n_elements(mag))
endelse
; Using good points, find maximum vector magnitude for scaling.
if (maxvec eq -1.) then begin
mag2 = mag(good) ;Get magnitude of good points.
if (max(mag2) le 2) then maxvec = fix(max(mag2))
if (max(mag2) gt 2) then maxvec = fix(max(mag2)+1)
if (round eq 1) then begin
maxvec = fix((max(mag2)+1)/5)*5 ;Round maxvec dwn to number
divisible by 5
print, 'Max vector length for scaling is made divisible by 5:
',maxvec
endif
if (maxvec eq 0.) then maxvec = 1
endif
;Grid spacing needed for scaling vectors
deltax = (max(x) - min(x)) / (s(1)-1)
deltay = (max(y) - min(y)) / (s(2)-1)
; Plot vectors and arrow heads (loop through all points).
for j = 0, s(2)-2, fix(everyy) do begin
for i = 0, s(1)-1, fix(everyx) do begin
; Get scaled vector componets.
; length = If three, the longest vector covers three grid cells.
; u,v = The actual velocity components.
; maxvec = The maximum wind component.
if (mag(i,j) lt missing) then begin
dx = length * (deltax) * (u(i,j)/maxvec) ;Get (u,v) components
dy = length * (deltay) * (v(i,j)/maxvec) ;that will be plotted
x0 = x(i) ;Get beginning/ending coords of vector
x1 = x0 + dx
y0 = y(j)
y1 = y0 + dy
if (y0 ge latmin and y1 le latmax and $
x0 ge lonmin and x1 le lonmax) then begin
arrow_andy, x0, y0, x1, y1, color=color, /data, $
hsize=float(arrowsize)*(!d.x_size/94.)*(mag(i,j)/(2.*maxvec) )
endif
endif
endfor
endfor
; Plot a "maximum vector" arrow at the bottom righthand corner of the plot
if n_elements(refvec) gt 0 then begin
; Determine new arrow head size and angle for the reference vector
r = .35 ;Length of arrow head
angle = 15. * !dtor ;Half-co-angle of arrowhead
st = r * sin(angle) ;Sin 15 degs * length of head
ct = r * cos(angle)
dx = length * deltax ;Get x-component
dy = length * deltay ;Get y-component
dy=0
; Compute (or use supplied value) for the ending x position, and the
; y position of the reference vector.
if n_elements (refposx) le 0 then refposx= max(x) - dx*3.
if n_elements (refposy) le 0 then refposy= min(y) - (y(3)-y(0))
x0 = refposx - dx
y0 = refposy
x1 = x0 + dx
y1 = y0 + dy ;No y variation (reference vector is horizontal)
; Find default (x,y) positions for max vector label
xlabel = (x0 + x1)/2.
ylabel = y0 - (y(4)-y(0))
if n_elements(reflabely) gt 0 then ylabel=reflabely
; Determine (or use supplied value) unit of the reference vector
if n_elements(refunit) le 0 then refunit= 'm s!U-1!n'
max_label = strcompress(string(maxvec), /remove_all) ;Get maxvec
reftitle = max_label + ' '+ refunit
xyouts, xlabel, ylabel, reftitle, align=.5, charsize=charsize,
color=color
; Found it more universally acceptable to plot refvec in normalized coords.
new_coords = convert_coord (x0, y0, /data, /to_norm)
xx0 = new_coords(0) & yy0 = new_coords(1) ;refvec starts here
new_coords = convert_coord (x1, y1, /data, /to_norm)
xx1 = new_coords(0) & yy1 = new_coords(1) ;refvec ends here
new_coords = convert_coord ( x1-(ct*dx-st*dy), y1-(ct*dy+st*dx),$
/data, /to_norm)
xx2 = new_coords(0) & yy2 = new_coords(1) ;top arrowheads end here
new_coords = convert_coord ( x1-(ct*dx+st*dy), y1-(ct*dy-st*dx),$
/data, /to_norm)
xx3 = new_coords(0) & yy3 = new_coords(1) ;bot arrowheads end here
plots,[xx0, xx1, xx3, xx1, xx3], $
[yy0, yy1, yy3+2.*(yy1-yy3), yy1, yy3], color=color, $
thick=1., /norm
endif
; Place dots at missing data points
if nbad gt 0 then $
oplot, x(bad mod s(1)), y(bad/s(1)), psym=3, color=color
end
|
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