Predicates (and fix minimize so that tests pass)

[papajohn]

No description provided.

[papajohn]

Implements #207

[SamLau95]

This means that all the functions in predicates.py will be in the global scope when we run from datascience import *.

Are we concerned about potential name conflicts since predicates.py has a lot of functions?

[SamLau95]

Looks mostly good to me, aside from a question and a suggestion.

We should also add predicates.py to the docs by adding a line in docs/index.rst and creating a predicates.rst file that looks like the util.rst file.

[papajohn]

I suppose we could put all predicate functions as attributes of some
class... I'll think about it. Something like,

t.where('age', Item.between(3, 8))

On Sun, Mar 6, 2016 at 2:55 AM, Sam Lau notifications@github.com wrote:

Looks mostly good to me, aside from a question and a suggestion.

We should also add predicates.py to the docs by adding a line in
docs/index.rst and creating a predicates.rst file that looks like the
util.rst file.

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#209 (comment).

[peterasujan]

If you end up pursuing this method, I might suggest using "is" (I guess it should be capitalized though) as the class name, so that the whole line reads (almost) like English.

[papajohn]

Ok, all single predicates are now methods of are. (I considered Is, but requires caps to avoid keyword and ls and Is look the same.)

I left both and either in the global namespace as well as in are because it looks prettier...

t.where('age', either(are.equal_to(5), are.above(8))

vs

t.where('age', are.either(are.equal_to(5), are.above(8))