A function possible inputs in PYTHON

Question

How can I quickly check what are the possible inputs to a specific function? For example, I want to plot a histogram for a data frame: df.hist(). I know I can change the bin size, so I know probably there is a way to give the desired bin size as an input to the hist() function. If instead of bins = 10 I use df.hist(bin = 10), Python obviously gives me an error and says hist does not have property bin.

I wonder how I can quickly check what are the possible inputs to a function.

• juanpa.arrivillaga: Generally, you need to read the documentation.
• Chris: An editor or IDE with decent completion can help too.
• Mahraz: I know the best way is always reading the documentation but sometimes, like the example I described above, you have a good guess of what the input should look like and I was looking for a way to verify quickly.

Answer 1

Since your question tag contains jupyter notebook I am assuming you are trying on it. So in jupyter notebook 2.0 Shift+Tab would give you function arguments.

Answer 2

One way is to see if there is documentation on the function itself:

from pandas import DataFrame as DF
help(DF.hist)

Alternatively, if you are inside IPython, using DF.hist? will work as well.

Answer 3

You can use the help function:

help(df.hist)

Also:

df.hist? # in ipython only

The possible arguments will print into the console.

• Chris: The ? suffix syntax isn't part of Python. It's something that iPython adds.

Answer 4

You can use the inspect module

def f(x, y):
 return x + y
print(inspect.signature(f))

See the documentation of the module for details regarding the returned type.