API: select_dtypes

[jreback]

related #7308
related #7314

maybe something like this

df.get_for_dtypes(types)

types could be a list of string/dtypes or a dtype/string

e.g.

'float64'
['float']
['float32','float64','object']
['float',np.dtype('bool')]
['numeric']
['datetime','timedelta']

are possible values

pretty easy to implement (just translate the types and filter on the blocks, ala _get_numeric_data)

[jreback]

if anyone could think of a better name.... :)

[cpcloud]

cols_with_type(list_o_types)

[jreback]

could also have a signature

``df.get_for_dtypes(include=..., exclude=....)`

[TomAugspurger]

Is this intended for internal use only, or for everyone?

[jreback]

I think external (user) use; (as we already have _get_numeric_data/_get_bool_data (and could make another if necessary