List user defined variables, python

Question

I am trying to iterate through the variables set in a python script. I came across the following:

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

and in the first example:

#!/us/bin/python                                                                                    

foo1 = "Hello world"
foo2 = "bar"
foo3 = {"1":"a", "2":"b"}
foo4 = "1+1"

for name in dir():
    myvalue = eval(name)
    print name, "is", type(name), "and is equal to ", myvalue

It lists all the variables stored in memory. I want to isolate the variables I have created in my script and not list the system variables created by default. Is there any way to do this?

Solution 1

If you don't put any underscores in front of your variables you could do:

#!/us/bin/python                                                                                    

foo1 = "Hello world"
foo2 = "bar"
foo3 = {"1":"a", "2":"b"}
foo4 = "1+1"

for name in dir():
    if not name.startswith('__'):
        myvalue = eval(name)
        print name, "is", type(myvalue), "and is equal to ", myvalue

Solution 2

You can strip out variables that are included in your module by default by checking if they are in the builtin __builtins__ module, like this:

>>> x = 3
>>> set(dir()) - set(dir(__builtins__))
set(['__builtins__', 'x'])

The only thing this doesn't strip out is __builtins__ itself, which is easy to special case.

Also note that this won't work if you have re-defined any builtin names. You shouldn't do this in practice, but a lot of people do, many by accident.

Solution 3

Here is solution.

#!/us/bin/python    

not_my_data = set(dir())

foo1 = "Hello world"
foo2 = "bar"
foo3 = {"1":"a", "2":"b"}
foo4 = "1+1"

my_data = set(dir()) - not_my_data

for name in my_data :
    myvalue = eval(name)
    print name, "is", type(name), "and is equal to ", myvalue

but this is bad practice.

You should use something like

#!/us/bin/python    
my_data = dict()                                                                                   
my_data['foo1'] = "Hello world"
my_data['foo2'] = "bar"
my_data['foo1'] = {"1":"a", "2":"b"}
my_data['foo1'] = "1+1"

for name in my_data :
    myvalue = eval(my_data[name])
    print name, "is", type(name), "and is equal to ", myvalue

Solution 4

The question title leads me to see this. But this is not what I wanted.

self-answering is below

[s for s in dir() if not '__' in s]

View more solutions

Comments

[interjay]

dir() doesn't give the names in __builtins__ for me (Python 2.7). All I get is ['__builtins__', '__doc__', '__name__', '__package__'].

[jterrace]

@interjay it gives some other things though, like __doc__ and __name__ that I think OP wants stripped out

[interjay]

But that has nothing to do with __builtins__, they are just names which are defined in every module (and therefore happen to be in __builtins__ as well). Calling them "builtin variables" is misleading.