Question

I have the following method:

def get_data(replace_nan=False):
    if replace_nan is not False
        data[numpy.isnan(data)] = replace_nan
        return data
    else:
        return data[~numpy.isnan(data)]

So, if replace_nan is False, we return some data array but remove NaNs, and if it’s anything else, we replace NaNs with the argument.

Problem is, I may want to replace NaN with False. Or anything else, for that sake. What’s the most pythonic way to do so? This:

def get_data(**kwargs):
    if "replace_nan" in kwargs:
       ...

works, but is semantically ugly (because we’re really just interested in one keyword argument, replace_nan) Any suggestions how to handle this case?

Answer 1

Usually people use None as the default value and then check for is not None.

If you need to allow None, too, use a dummy object:

__default = object()
def get_data(replace_nan=__default):
    if replace_nan is __default:
        ...