IDL

• Interactive use
• Writing IDL procedures and running them

• Documentation
• Astronomy Users Library

• print
• variables and arrays
  • initialize arrays using var=fltarr(nx,ny) (or intarr)
• arithmetic
• strings
• conditionals
• loops
• functions (return a value) and procedures (don't return value, but can modify arguments)

• Start IDL: idl
• Define some numerical variables, and do some arithmetic with them
• Define some string variables, and do some operations with them
• Write some operations in a file, and then execute the file from the command line, and from within ipython

• Astronomy users library
• SDSS tools: idlutils, idlspec2d
• Finding routines: IDL_PATH environment variable

• IDL Users library readcol routine (library must be in IDL_PATH!)
  • each column is read into an array variable
  • readcol,'filename',c1,c2,c3,c4,c5,c6[,format=('fffff') (variable names for columsn can be anything you want, formats are fda for float (default), integer, character)
• IDL Users library mrdfits routine (library must be in IDL_PATH!)
  • var=mrdfits('filename'[,ext,head=head]) reads data from specified extension into var
  • table data is read into a structure variable, access elements using e.g. var.colname
  • help,var to see the columns

• As above for Python, but IDL

• plot,x,y[,xtit=xtitle,ytit=ytitle,xr=[xmin,max],yr=[ymin,ymax]]
• oplot

• plots command allows you to specify color (between 0-255) and size of a point

    plots,x,y,color=(z-zmin)*(zmax-zmin),size=size
  

• so far as I know, for color-coded and/or size-coded points, need to plot one point at a time in a loop over array elements:

• As above for Python, but IDL