Column.is_in

[MarcoGorelli]

In the last call it was brought up that perhaps we should add Column.is_in

This can be achieved with the existing Standard methods:

result = column == values[0]
for value in values[1:]:
    if math.isnan(value):
        result |= column.isnan()
    elif value is namespace.null:
        result |= column.isnull()
    else:
        result |= column == value

so it really just be a convenience method. No objections to adding it anyway

[jorisvandenbossche]

Apart from convenience, an additional reason that many DataFrame libraries have a function like this is also because it can be much more performant with a custom implementation, compared to the generic code above.

(also, your code needs a slight edit to support NaN/null as first value, so probably it would be easiest to start result with an all-False column)

[MarcoGorelli]

right, thanks - OK, I'll make a PR then, this probably needs to be included