What this does is whichever row for A contains the numbers between 5 and 10, it restricts column B to those same rows. Examples of this:Īrevised=where(a ge 5 and a le 10,countsa) You can also restrict one column and use data from the other columns that match up with your restricted columns data. You can also use this command to count the total amount of numbers/elements in your restricted data. 'a' is the column name that we are restricting, and the arevised is just the title for this restricted data. Ge stands for greater than or equal to, and le stands for less than or equal to. If we wanted to pull out just the numbers between 5 and 10, we could do something like this:

Looking at our column A, it runs from 0 to 15. Using this command you can restrict your data to certain ranges. Use the '?' help feature, and type in plot to get a complete list of commands.Īnother command that you are going to use a lot is the 'WHERE' command. You can also change the symbol used to plot the data, using the 'psym=#', where # is any number 1-10. You can find a complete list of the colors by typing in '?' into idl, and then typing in color in the search window. For colors, it is done by a number system, with 250 being red. To add commands, we just add a comma and then add whichever command we want. If you notice, we have to read our 'X' variable first, then Y.

Let's try plotting column B versus column A: Want our axis labeled, or what color we should use. We have to tell IDL what our variables are, and we can also tell it how we

The command to plot things is.plot, you guessed it. Remember, our file has 3 columns, a/b/c in order, so: An example of the basic format, using the datafile. You want to specify the filename after readcol, and then all the column names so you can call them later on. Readcol : This reads in the columns of the file you want to use. This should be your first step on anything if you get stuck. ? : The ? opens up the IDL help window, allowing you to search through the manual and the list of commands. Then type IDL in the command line.īefore we start doing any work, I'll list the most useful command in IDL, the '?' This exercise is intended to go through basic commands in IDL to make basic plots, sort data based on specific parameters, and make a for-loop.

Idl plots