This procedure performs labeling of lat/lon points around the
edge of a map. It is pretty specific to the way I prefer things,
but it may help you with your problem as well. Good luck with it.
It is a bit verbose, but seems to do the job with a variety of
map projections...
; Procedure to label the lat/lon values around the boundary of a map.
;
; Originator: Andrew F. Loughe (2/22/95)
pro map_label, color=color, charsize=charsize, $
lhs=lhs, rhs=rhs, $
latdel=latdel, londel=londel, $
nudgex=nudgex, nudgey=nudgey, help=help
; Print a help message to the IDLTERM.
if (n_elements(help) gt 0) then begin
message, ' map_label, color=color, charsize=charsize,' + $
' lhs=lhs, rhs=rhs, latdel=latdel, londel=londel,' + $
' nudgex=nudgex, nudgey=nudgey, help=help'
endif
; Set some defaults
if (n_elements(color) eq 0) then color = !p.color
if (n_elements(charsize) eq 0) then charsize = 0.8
lhs = keyword_set (lhs)
rhs = keyword_set (rhs)
if (lhs eq 0 and rhs eq 0) then lhs = 1
if (n_elements(latdel) eq 0) then latdel = 30
if (n_elements(londel) eq 0) then londel = 30
if (n_elements(nudgex) eq 0) then nudgex=0
if (n_elements(nudgey) eq 0) then nudgey=0
on_error, 2
; Get lat/lon boundaries of the map.
lonmin = !map.out(2)
lonmax = !map.out(3)
latmin = !map.out(4)
latmax = !map.out(5)
if (lonmin eq lonmax) then lonmax = lonmin + 360.
DX = abs (lonmax - lonmin)
; Determine character height and width. Apply charsize.
char_ht = convert_coord([0,!d.y_ch_size],/device,/to_norm)
char_ht = char_ht(1) * 1.0
if (!d.name ne 'X' and charsize gt 1.) then $
char_ht = char_ht * charsize
char_wd = convert_coord([0,!d.x_ch_size],/device,/to_norm)
char_wd = char_wd(1)
; Nudging factor (convert from data to normalized)
y_avg = .5*(latmin + latmax)
nudgex1 = convert_coord( [nudgex,y_avg], /data, /to_norm )
nudgex2 = convert_coord( [nudgex+nudgex,y_avg], /data, /to_norm )
nudgex = nudgex2 - nudgex1
nudgex = nudgex(0)
x_avg = .5*(lonmin + lonmax)
nudgey1 = convert_coord( [x_avg,nudgey], /data, /to_norm )
nudgey2 = convert_coord( [x_avg,nudgey+nudgey], /data, /to_norm )
nudgey = nudgey2 - nudgey1
nudgey = nudgey(1)
; Test to see how close the lower longitude points are.
; If they are too close, then place longitude labels along EQ.
xypos1 = convert_coord([lonmin, latmin], /data, /to_norm)
xypos2 = convert_coord([lonmin+DX/2., latmin], /data, /to_norm)
bottom = 'yes'
if ( abs(xypos1(0) - xypos2(0)) lt .2 ) then bottom='no'
; Plot longitude labels along BOTTOM boundary of the map.
for i = fix(lonmin), fix(lonmax) do begin
if ( (i mod londel) eq 0 ) then begin
ii = fix(abs(i))
if (i gt 180) then ii = abs(360 - ii)
; Determine text of longitude label.
append = ''
if (i gt 0 and i lt 180) then append='E'
if (i lt 0 or i gt 180) then append='W'
if (i gt 360 and i lt 540) then append='E'
if (i gt 540 and i lt 720) then append='w'
if ( (abs(i) mod 180) eq 0 ) then append=''
if ( (abs(i) mod 360) eq 0 ) then ii='0'
label = strcompress(string(ii), /rem) + append
; Determine where to place longitude label.
xypos = convert_coord([i, latmin], /data, /to_norm)
x = xypos(0)
y = !y.window(0) - (char_ht)*1.2 + nudgey
; Some projections have longitude labels at EQ.
if ( bottom eq 'no' ) then begin
xypos = convert_coord([i, .5], /data, /to_norm)
x = xypos(0)
y = xypos(1)
if ( x ge !x.window(0)+char_wd*2. and $
x le !x.window(1)-char_wd*2. and $
y ge !y.window(0)+char_ht and $
y le !y.window(1)-char_ht ) then $
xyouts,x,y,label,charsize=charsize,color=color,align=.5,/nor m
endif else begin
; Plot longitude labels at bottom of the map.
if ( x ge !x.window(0)+char_wd*2. and $
x le !x.window(1)-char_wd*2. ) then $
xyouts,x,y,label,charsize=charsize,color=color,align=.5,/nor m
endelse
endif
endfor ; i
; Plot latitude labels along LEFT or RIGHT boundary of the map.
for i = latmin, latmax do begin
if ( (i mod latdel eq 0) ) then begin
ii = fix(abs(i))
; Determine text of latitude label.
append=''
if (i lt 0) then append='S'
if (i gt 0) then append='N'
if (i eq 0) then ii='EQ'
label = strcompress(string(ii), /rem) + append
; Determine where to place latitude label.
; Work in from the far left to find the y position.
if (lhs eq 1) then begin
for x1 = lonmin-10., lonmax, .1 do begin
xypos = convert_coord( [x1, i], /data, /to_norm)
xypos2 = xypos
xypos2(0) = xypos2(0) - char_wd
xypos2(1) = xypos2(1) + char_ht
if (xypos2(0) ge !x.window(0) and xypos2(1) ge $
!y.window(0) and xypos2(1) le !y.window(1)) $
then goto, jump2
endfor
; Work in from the far right to find the y position.
endif else begin
for x1 = lonmax+10., lonmin, -.1 do begin
xypos = convert_coord( [x1, i], /data, /to_norm)
xypos2 = xypos
xypos2(0) = xypos2(0) + char_wd
xypos2(1) = xypos2(1) + char_ht
if (xypos2(0) le !x.window(1) and xypos2(1) ge $
!y.window(0) and xypos2(1) le !y.window(1)) $
then goto, jump2
endfor
endelse
jump2: y = xypos(1) - (char_ht*.25)
; Move end latitudes around a bit.
if (i eq latmax) then y = xypos(1) - (char_ht * .2)
if (i eq latmin) then y = xypos(1)
; Find lefthand or righthand side of the plot boundary.
if (lhs eq 1) then x = !x.window(0) - (char_wd*.5) + nudgex
if (rhs eq 1) then x = !x.window(1) + (char_wd) + nudgex
; Plot latitude label.
xyouts, x, y, label, charsize=charsize, color=color, $
align=(lhs eq 1), /norm
endif
endfor ; i
end
--
Andrew F. Loughe email: afl@cdc.noaa.gov
University of Colorado, CIRES voice: (303) 492-0707
Campus Box 449 fax: (303) 497-7013
Boulder, CO 80309-0449 USA
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