python: viewing all defined variables

Question

I'm currently working on a computation in python shell. What I want to have is Matlab style listout where you can see all the variables that have been defined up to a point (so I know which names I've used, their values and such).

Is there a way and how would one go in python about that ?

Answer 1

To get the names:

for name in vars().keys():
  print(name)

To get the values:

for value in vars().values():
  print(value)

vars() also takes an optional argument to find out which vars are defined within an object itself.

Answer 2

print locals()

edit continued from comment.

To make it look a little prettier when printing:

import sys, pprint
sys.displayhook = pprint.pprint
locals()

That should give you a more vertical printout.

Answer 3

Couple of things you could use:

• dir () will give you the list of in scope variables:
• globals () will give you a dictionary of global variables
• locals () will give you a dictionary of local variables

Answer 4

globals(), locals(), vars(), and dir() may all help you in what you want.

Answer 5

keep in mind dir() will return all current imports, AND variables.

if you just want your variables, I would suggest a naming scheme that is easy to extract from dir, such as varScore, varNames, etc.

that way, you can simply do this:

for vars in dir():
 if vars.startswith("var"):
   print vars

Edit

if you want to list all variables, but exclude imported modules and variables such as:

__builtins__

you can use something like so:

import os
import re

x = 11
imports = "os","re"

for vars in dir():
    if vars.startswith("__") == 0 and vars not in imports:
     print vars

as you can see, it will show the variable "imports" though, because it is a variable (well, a tuple). A quick workaround is to add the word "imports" into the imports tuple itself!

Answer 6

If this is an option for you, you might want to look at IPython:

To get a list of all currently defined variables, type who:

In [1]: foo = 'bar'

In [2]: who
foo

You can type whos for more detail:

In [3]: whos
Variable   Type    Data/Info
----------------------------
foo        str     bar

There are a wealth of other functions available - basically it is the Python interpreter on steroids. One convenient one is store command, which lets you save variables between sessions (kind of like a super easy pickle)

If you have a few minutes, check out Jeff Rush's excellent IPython demonstration screencasts:

I am in no way associated with the team behind IPython, just a satisfied user.

Answer 7

Already been asked, I posted this a while back, it's at:

Enumerate or list all variables in a program of [your favorite language here]