idl> n = 10
   idl> y = findgen(n) 
   idl> plot, y 

  idl> print, findgen(6)
        0.00000      1.00000      2.00000      3.00000      4.00000      5.00000

Using IDL plot command is quite inconvenient to save the figure as a postscript. In addition, positioning the figure on the window/page by using !p.position, !p.region and !p.multi is often a nightmare. That's why we developed splot (like super-plot) which can be used in the same way as plot but is much more convenient to make postscript and position the figure.

  idl> splot, y 
  % Compiled module: SPLOT.
  % Compiled module: REINITPLT.
  % Compiled module: PLACEDESSIN.
  % Compiled module: CALIBRE.
  % Compiled module: GIVEWINDOWSIZE.
  % Compiled module: GET_SCREEN_SIZE.
  % Compiled module: TERMINEDESSIN.

Save the figure seen on the screen as a (real, not a screen capture) postscript in only one command.

  idl> @ps
  % Compiled module: GETFILE.
  % Compiled module: PUTFILE.
  % Compiled module: OPENPS.
  % Compiled module: XQUESTION.
  Name of the postscript file? (default answer is idl.ps)first_ps 
  % Compiled module: ISAFILE.
  % Compiled module: XNOTICE.
  % Compiled module: CLOSEPS.
  % Compiled module: PRINTPS.
  % Compiled module: FILE_WHICH.
  % Compiled module: CW_BGROUP.
  % Compiled module: XMANAGER.

Check that the “first_ps.ps” file is now existing …

  idl> print, file_test(psdir + 'first_ps.ps')
             1
  idl> help, file_info(psdir + 'first_ps.ps'), /structure
  ** Structure FILE_INFO, 21 tags, length=64, data length=63:
     NAME            STRING    '/Users/sebastie/IDL/first_ps.ps'
     EXISTS          BYTE         1
     READ            BYTE         1
     WRITE           BYTE         1
     EXECUTE         BYTE         0
     REGULAR         BYTE         1
     DIRECTORY       BYTE         0
     BLOCK_SPECIAL   BYTE         0
     CHARACTER_SPECIAL
                     BYTE         0
     NAMED_PIPE      BYTE         0
     SETUID          BYTE         0
     SETGID          BYTE         0
     SOCKET          BYTE         0
     STICKY_BIT      BYTE         0
     SYMLINK         BYTE         0
     DANGLING_SYMLINK
                     BYTE         0
     MODE            LONG               420
     ATIME           LONG64                1122424373
     CTIME           LONG64                1122424373
     MTIME           LONG64                1122424373
     SIZE            LONG64                      4913

splot accepts the same keywords as plot (/ISOTROPIC, MAX_VALUE=value, MIN_VALUE=value, NSUM=value, /POLAR, THICK=value, /XLOG, /YLOG, /YNOZERO), including the graphics keywords (BACKGROUND, CHARSIZE, CHARTHICK, CLIP, COLOR, DATA, DEVICE, FONT, LINESTYLE, NOCLIP, NODATA, NOERASE, NORMAL, POSITION, PSYM, SUBTITLE, SYMSIZE, T3D, THICK, TICKLEN, TITLE, [XYZ]CHARSIZE, [XYZ]GRIDSTYLE, [XYZ]MARGIN, [XYZ]MINOR, [XYZ]RANGE, [XYZ]STYLE, [XYZ]THICK, [XYZ]TICKFORMAT, [XYZ]TICKINTERVAL, [XYZ]TICKLAYOUT, [XYZ]TICKLEN, [XYZ]TICKNAME, [XYZ]TICKS, [XYZ]TICKUNITS, [XYZ]TICKV, [XYZ]TICK_GET, [XYZ]TITLE, ZVALUE).

It can therefore be customized as much as you want. See this short example:

  idl> splot, y, y^2, linestyle = 2, thick = 2, title = 'y = x^2', /portrait 

splot can be used to setup the graphic environment (!p, !x, !y, !z variables) needed by procedures like oplot

  idl> splot, y, yrange = [0, (n-1)^2], title = 'x and x^2'
  idl> oplot, y^2, color = 50, linestyle = 2 

Use the keyword small to produce multi plots figures.

  idl> splot, y, y^2, title = 'y = x^2', psym = 2, small  = [1, 2, 1]
  idl> splot, findgen(360)/36., findgen(360)*2.*!dtor, /polar $
  idl>     , small  = [1, 2, 2], /noerase  

Following splot example, we provide scontour as a “super contour”.

  idl> z = dist(n)
  % Compiled module: DIST.
  idl> scontour, z 
  % Compiled module: SCONTOUR.
  % Compiled module: CHKSTRU.

scontour accepts the same keywords as contour (C_ANNOTATION=vector_of_strings, C_CHARSIZE=value, C_CHARTHICK=integer, C_COLORS=vector, C_LABELS=vector{each element 0 or 1}, C_LINESTYLE=vector, { /FILL | /CELL_FILL | C_ORIENTATION=degrees}, C_SPACING=value, C_THICK=vector, /CLOSED, /DOWNHILL, /FOLLOW, /IRREGULAR, /ISOTROPIC, LEVELS=vector, NLEVELS=integer{1 to 60}, MAX_VALUE=value, MIN_VALUE=value, /OVERPLOT, {/PATH_DATA_COORDS, PATH_FILENAME=string, PATH_INFO=variable, PATH_XY=variable}, TRIANGULATION=variable, /PATH_DOUBLE, /XLOG, /YLOG, ZAXIS={0 | 1 | 2 | 3 | 4}), including the graphics keywords (except LINESTYLE, PSYM, SYMSIZE).

It can therefore be customized as much as you want. See these short examples:

  idl> scontour, z, /fill, nlevels = 15, subtitle = 'nicer contour' $
  idl>     , xtitle = 'x index', charsize = 1.5 

It can be used in combination with contour to make more complex plots:

  idl> ind = findgen(2*n)/(2.*n)
  idl> scontour, z, levels = n*ind, c_orientation = 180*ind, c_spacing = 0.4*ind
  idl> contour, z, /overplot, c_label = rebin([1, 0], 2, n) , levels = n*ind $
  idl>     , c_charthick = 2, c_charsize = 1.5, c_colors = 250*ind 

  idl> print, rebin([1, 0], 2, 3)
         1       0
         1       0
         1       0

scontour is compatible with the positioning method associated with the small keyword. See for example the test file tst_basic.pro:

  idl> tst_basic 

tvplus is a enhanced version of tvscl and allow you to have a quick look and perform basic exploration of 2D arrays.

 idl> tvplus, dist(20) 
 left button  : mouse position and associated array value
 middle button: use it twice to define a zoom box
 right button : quit
 (x, y) = (  5,   5), value = 7.07107
 (x, y) = ( 12,   8), value = 11.3137
 

For more informations on tvplus, try:

 idl> xhelp, 'tvplus'

To see the source code of tvplus, try:

 idl> xfile, 'tvplus'

 idl> ?tvplus

pltv is a mix between tvplus and plt and allow you to have formal quick look of 2D arrays.

  idl> pltv, dist(20) 
  

Example of Levitus temperature on a regular 1x1 grid.

  idl> @tst_initlev
  % Compiled module: INITNCDF.
  % Compiled module: ISAFILE.
  % Compiled module: UNIQ.
  % Loaded DLM: NCDF.
  % Compiled module: COMPUTEGRID.
  % Compiled module: DOMDEF.
  % Compiled module: INTER.
  % Compiled module: TRIANGULE.
  % Compiled module: TRIANGULE_C.
  % Compiled module: UNDEFINE.
  % Compiled module: TESTVAR.
  % Compiled module: DIFFERENT.
  % Compiled module: DEFINETRI.
  

This @tst_initlev command allows us to define:

  idl> help, jpi,jpj,jpk
  JPI (LOCAL_COORD)   LONG      =          360
  JPJ (LOCAL_COORD)   LONG      =          180
  JPK (LOCAL_COORD)   LONG      =           33
  idl> help, glamt, gphit,glamf, gphif
  GLAMT (LONGITUDES)  FLOAT     = Array[360, 180]
  GPHIT (LATITUDES)   FLOAT     = Array[360, 180]
  GLAMF (LONGITUDES)  FLOAT     = Array[360, 180]
  GPHIF (LATITUDES)   FLOAT     = Array[360, 180]
  idl> help, gdept, gdepw
  GDEPT (VERTICAL)    FLOAT     = Array[33]
  GDEPW (VERTICAL)    FLOAT     = Array[33]
  idl> help, e1t, e2t, e3t
  E1T (SCALE_FACTORS) FLOAT     = Array[360, 180]
  E2T (SCALE_FACTORS) FLOAT     = Array[360, 180]
  E3T (VERTICAL)      FLOAT     = Array[33]
  idl> help, tmask
  TMASK (MASKS)       BYTE      = Array[360, 180, 33]
  idl> help, triangles_list
  TRIANGLES_LIST (LIEES_A_TRIANGULE) LONG      = Array[3, 128880]
  idl> tvplus, glamt*tmask[*,*,0]
  idl> tvplus, gphit*tmask[*,*,0]
  

We provide other initialization methods/examples

When the grid is really irregular (its abscissa and ordinate cannot be descried by a vector), loading the grid directly from the data forces us to make an approximation when computing the grid corners position and the cells size. In that case, it can be preferable to load the grid from the meshmask file created by OPA. As OPA use a Arakawa-C discretization, loading the grid from the meshmask will also define all parameters related to the U, V and F grids (glam[uv],gphi[uv], e[12][uvf]). Note that, when using a simple grid definition from the data itself (with initncdf or computegrid), adding the keyword /FULLCGRID leads also to the definition of all U, V and F grids parameters. There is the examples to load ORCA grids from OPA meshmask.