Testing if a pandas DataFrame exists

Question

In my code, I have several variables which can either contain a pandas DataFrame or nothing at all. Let\'s say I want to test and see if a certain DataFrame has been created ye

Answer 1

Option 1 (my preferred option)

This is @Ami Tavory's

Please select his answer if you like this approach

It is very idiomatic python to initialize a variable with None then check for None prior to doing something with that variable.

df1 = None

if df1 is not None:
    print df1.head()

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Option 2

However, setting up an empty dataframe isn't at all a bad idea.

df1 = pd.DataFrame()

if not df1.empty:
    print df1.head()

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Option 3

Just try it.

try:
    print df1.head()
# catch when df1 is None
except AttributeError:
    pass
# catch when it hasn't even been defined
except NameError:
    pass

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Timing

When df1 is in initialized state or doesn't exist at all

When df1 is a dataframe with something in it

df1 = pd.DataFrame(np.arange(25).reshape(5, 5), list('ABCDE'), list('abcde'))
df1