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IDL 8.0 Graphics: A Primer in the new Graphical System

IDL 8.0 Graphics: A Primer in the new Graphical System. Jonathan Fairman UAH Atmospheric Science 3/4/11 and 3/7/11 Short Course. What’s new in IDL 8.0?. New graphics system New plotting routines New mapping routines New contour routines New vector routines Ability to do streamlines!.

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IDL 8.0 Graphics: A Primer in the new Graphical System

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  1. IDL 8.0 Graphics: A Primer in the new Graphical System Jonathan Fairman UAH Atmospheric Science 3/4/11 and 3/7/11 Short Course

  2. What’s new in IDL 8.0? • New graphics system • New plotting routines • New mapping routines • New contour routines • New vector routines • Ability to do streamlines!

  3. Overview • New System Introduction • Changes to PLOT • Annotations: TEXT, LEGEND • New routines: BARPLOT, ERRORPLOT • Changes to CONTOUR • COLORBAR • Changes to IMAGE • Changes to MAP • MAPGRID, MAPCONTINENTS • New Routines • VECTOR, STREAMLINE • Bugaboos with new routines

  4. So, what’s this new system, anyways? • Functional graphics • Old IDL direct graphics were procedural • Aspects of iPlot tools/object graphics systems • Scriptable • Dynamic Plot Changes without redrawing • Smart saving images • Old direct graphics system still works, so your code will still produce the plots • However, some things are worth merging over

  5. Graphics basis • No need to set device keywords • Opens new window with white background automatically • Stores graphical variables in memory, dynamically addressable • LaTeX-like syntax for special characters • Colors are stored in the system • Symbols are stored in the system • Can use text to specify symbols and colors (versus old specification of numbers) • Let’s start with just introducing the WINDOW W1 = window()

  6. Old code: Device, decomposed=0, retain=2 !p.background = 255 Loadct, 39, /silent Window, 0, xs=600, ys=600 Plot, findgen(10), color=0, /nodata oplot, findgen(10), color=250 New Code: P=plot(findgen(10), color=‘red’,$ dimensions=[600,600]) PLOT

  7. PLOT • Properties: • Under the old code, had to specify everything in one statement, e.g.: Plot, findgen(33)/16*!pi, sin(findgen(33)/16*!pi), color=0, xrange=[0,2*!pi], $ yrange=[-1,1], charsize=2.0, ystyle=1, xstyle=1 , $ ytitle=‘Y = sin(x), xtitle =‘ x = [0,2!7p!8]’,/nodata oplot, findgen(33)/16*!pi, sin(findgen(33)/16*!pi), color=250, thick=2 Oplot, findgen(33)/16*!pi, sin(findgen(33)/16*!pi), psym=3, color=0 • New code is dynamic – can set things separately as well as together P1=plot(findgen(33)/16*!pi, sin(findgen(33)/16*!pi)) P1.color=‘red’ P1.xrange=[0,2*!pi] P1.ytitle=‘Y = sin(x)’ P1.xtitle =‘x = [0, 2$\pi$] ;this is equivalent to: P1.symbol=‘plus’ P1.sym_color=‘black’ P1 = plot(findgen(33)/16*!pi, sin(findgen(33)/16*!pi), color=‘red’,$ xrange=[0,2*!pi, ytitle=‘y = sin(x)’, xtitle=‘x = [0, 2$\pi$],$ symbol=‘plus’

  8. Annotations • LEGEND: uses plot data to make legend, replacing old method of PLOTS and XYOUTS • TEXT: outputs text to screen (analogue: XYOUTS) • Create multiple plots with differing names • Use annotations.pro from collections

  9. BARPLOT • Draws a bar plot of data • Syntax: • B1 = BARPLOT(x, y) • Old syntax for bar plots in make_precip_barplot.pro • Let’s go to the code…

  10. ERRORPLOT • Specification: • E1 = ERRORPLOT(x,y,xerror,yerror) • Draws a box and whisker plot • All plot keywords the same • Find the code in make_precip_error.pro

  11. CONTOUR • Similar to other plotting systems, but with a twist! • Nonfilled contours similar to changes in PLOT system • Filled contours a little different… • Old code: Loadct, 39, /silent Max1 = max(data) Min1 = min(data) Contour, data, x, y, nlevels=251, /cell_fill, levels=findgen(251)/250.*(max1-min1) – min1, color=0 New code: C1 = contour(data,x,y,n_levels=251,/fill, rgb_table=39)

  12. COLORBAR • Remember how much of a pain making colorbars was? Not anymore! • Old code: Ncolors=255 Loc = [0.1,0.1,0.8,0.125] xsize= (loc(2) – loc(0))*D.X_VSIZE Ysize = (loc(3) – loc(1))*D.Y_VSIZE Xstart = loc(0)*D.X_VSIZE Ystart = loc(3) *D.Y_VSIZE Bar = BINDGEN(256)#REPLICATE(1B,10) Bar = BYTSCL(bar, top=ncolors-1) TV, CONGRID(bar, xsize, ysize), xstart+1, ystart=1 PLOT, findgen(251)/250., findgen(251)/250.*max1, /nodata, $ position=loc, yticks=1, ytickformat=‘(A1)’ yminor=1, xticklen=0.25,$ xrange=[min1,max1], xtitle=title1, color=0, /noerase, xstyle=1 • New code: Loc = [0.1,0.1,0.8,0.125] cbar1 = colorbar(target = c1, position = loc)

  13. CONTOUR and COLORBAR • Let’s go to the code… looking at the wind speed example • contour_windspeed.pro

  14. IMAGE • Replaces TV, does some other stuff as well… • Context: Im1 = image(bands, xval, yval, order=1) Old code: Tv, bands, xval, yval, order=1, true=3 -Still need order command to make things look right if you don’t rotate it -automatically senses if it’s a 3-band overlay (no more true=3) -Saves via im1.save, no more write_png, etc.

  15. MAP • Most overhauled routine • Moves it into more GIS/ENVI type mapping versus IDL direct mapping • Calling context: M1 = map(‘Equirectangular’, limit = [min(lat), min(lon), max(lat), max(lon)], position=[0.1,0.1,0.9,0.9], dimension=[900,900] Replaces: Map_set, limit = [min(lat), min(lon), max(lat), max(lon)], position = [0.1,0.1,0.9,0.9]

  16. MAP • The MAP command also leads to changes in MAPGRID and MAPCONTINENTS • Start a map… M1 = map(‘Geographic’, limit=[10,-130,50,-60], dimensions=[900,600]) Now, let’s change some properties… Mg1 = m1.mapgrid Mg1.linestyle = ‘Dash’ Mg1.label_position = ‘0’ Mg1.font_size=14 ;now, let’s add some continents Mc1 = mapcontinents(/countries) Mc1 = mapcontinents(/usa) ;now let’s change some properties! M1[‘Longitudes’].label_angle=0 M1[‘Ohio’].fill_color=‘red’ M1[‘Michigan’].fill_color=‘blue’

  17. MAP • The map works in projection space, not in the direct space anymore • So, let’s say we want to plot points in the map… of the NARR grid or something • Let’s go to plot_narr_latlon.pro

  18. VECTOR and STREAMLINE • Two new ways to plot wind features! • Some of these are pretty awesome! Context: V1 = vector(uwind, vwind, x, y, vector_style=‘barbs’) St1 = streamline(uwind, vwind, x, y, streamline_stepsize=0.1, streamline_nsteps=200) Let’s go to the code: start with stream_vector.pro

  19. Combination plots! • OK, so we have covered mapping, plotting, streamlines, vectors, colorbars… • Now let’s put some of these together in IDL 8.0 syntax. • Let’s look at combo_plot.pro and go from there…

  20. Bugaboos • Some issues that I haven’t figured out yet • More then these, just a brief synopsis • MAP • Inability to switch to decimal degrees • Haven’t quite figured out how to map a satellite image yet • Can’t specify position, automatically defined based on projection • Problems with multiple maps in the same window • CONTOUR • Filled contours have issue with fixed tables • Can be slow to save in EPS • COLORBAR • Can’t change range- specified in data • PLOT • Multiple axes can be slow if it’s not a direct multiplier • Skew-T in the new plotting system would be a nightmare

  21. Overview • IDL 8.0 makes simple things easier! • IDL 8.0 makes complex things harder! • Overall, adapt code as you see fit- I’m moving most of my new simple plotting (especially error and bar plots) to the new system, but will probably keep the old Direct Graphics for mapping and filled contours

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