How to Use Python for SPSS?

Summary

There are different ways to use Python in SPSS. The easiest is to just copy-paste-run the syntax you need. However, most users will at some point want to write their own Python syntax. Even more efficiency can be gained by passing code into functions and eventually modules. This tutorial walks you through the options from most basic to most advanced.

1. Copy Paste Run

In many cases, users can get things done by simply copying-pasting-running SPSS Python syntax. Usually, minor modifications are needed (such as specifying variables or folders). These should be obvious as long as a few basics are kept in mind.

2. Write Your Own Syntax

More flexibility and control can be gained by simply writing SPSS Python syntax yourself. Other users' SPSS Python syntax may provide very useful examples. The strictness of Python code, however, may require some practice to get used to.

3. Write Your Own Functions

If there are blocks of SPSS Python syntax you use a lot, you can sometimes define them as functions. In this case, you choose a function name for some task(s) and write code that should be executed when the function is called upon. The obvious advantage is that you don't need to repeat some block of code for each time you'd like to use it. Instead, after writing out a function just once, you can use it as many times as you like with a single line of code (possibly in a loop if desired).

4. Write Your Own Module

A Useful SPSS Python Module can be as Short as Five Lines of Code

This is where it gets really interesting. A module is a simple text file containing functions and/or other statements. By moving functions into a module, you don't need their code in your SPSS syntax files anymore. After importing your module, you can use each of its functions with a single line of code. This will render your SPSS syntax much shorter and more readable. Another advantage is that if you discover some mistake in one of your functions, you need to correct it just once (in your module). All syntax files that use this function will now use the corrected version and there's no need to correct each of them individually.

5. Create Custom Dialogs and Toolbar Tools

SPSS Syntax - including SPSS Python syntax - can be Pasted and/or run from the GUI (Graphical User Interface, the 'point-click menu'). There are two basic ways to do this.

Attach a toolbar item to a syntax file. Also, see SPSS Toolbar Tool Building. You can now run your syntax with a single left mouse click. However, this syntax won't be pasted in your syntax window and you can't pass any parameters into it.
Create an SPSS custom dialog. In this case, you'll need more than a single mouse click to run this syntax but you can pass one or more parameters (such as variables) into it and paste the result.

SPSS Custom Dialogs Render Python Accessible to Clients

Three Reasons for Creating your Own Menu Items

Accessibility. If you're working with a client, he may be not entirely comfortable with SPSS (Python) syntax. However, most users are at ease with using menu items regardless of what code is lying underneath them.
Ease. If you want to run a function from your own module, the function call should be exactly correct. That is, you must the exact function name (including the capitalization - if any) and the way parameters should be specified. By having a dialog window generate the function call for you, you don't need to memorize any of that.
Speed. A single mouse click is probably the fastest possible way to run syntax.

Note that IBM also offers additional functions called extension commands. See SPSS Extension Bundles for more on this.