In IDL you would use a, the equivalent in Python is a. If we have read in a standard atmosphere grid, in IDL it will appear as longitude, latitude, height, in Python it will appear as height, latitude, longitude. Python has a C style data interface while IDL has a Fortran style. The rules of operator precedence are the same as in IDL - an integer multiplied by a float gives a float. Indentation is the way of closing if then statements or loops in Python - there's no need for an endif or endfor as in IDL. Both Python and IDL indicies start at zero - i.e. In IDL this would be print, a,b,c.Īrray elements are accessed via brackets only. Use print a,b,c to see the variables a,b,c. As in IDL you can reassign variables to be different types. There is no need to declare variable types - just use them. In Python variable names case sensitive while in IDL they are case insensitive. Long integers can grow as large as is needed. A long integer is specified by putting a L or l after the number. Python integers are 32 bit and not 16 bit as in IDL. Python floats are at least 64 bit numbers. In Python no end statement or procedure/function name is needed. Import matplotlib.pyplot as plt - plottingįrom mpl_toolkits.basemap import Basemap, shiftgrid, addcyclic - mappingįrom subprocess import call - calling Unix programsįrom netCDF4 import Dataset as ncfile - netCDF I/OĪfter importing a package functions can then referenced - for example, np.mean(a) for the NumPy mean function. Import numpy as np - scientific computingįrom scipy import interpolate - interpolation In Python you have to explicitly import packages you need.
In IDL all the functionality of the language is available by just typing idl - maps, stats etc. Users outside the department will need Python with the NumPy, matplotlib, basemap and netCDF4 packages installed. To use the Canopy Enthought Python distribution in the Meteorology department type:
Please report any errors or ommisions to me - more detailed look at Python is available on-line at Johnny Lin's website.
This web page is intended to help get you started using Python and making plots with Matplotlib. Python for IDL users Python for IDL usersĪ guide for IDL users using Python for the first time.
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