iimport numpy as np
import pandas as pd
from pandas.testing import assert_index_equal

def master(self, other):
    return set(self._ndarray_values) & set(other._ndarray_values)

def pr(self, other):
    lvals = self._ndarray_values
    rvals = other._ndarray_values
    
    other_uniq = set(rvals)
    seen = set()
    return [x for x in lvals if x in other_uniq and not (x in seen or seen.add(x))]

def indexer(self, other):
    lvals = self._ndarray_values

    if self.is_monotonic and other.is_monotonic:
        rvals = other._ndarray_values
        return self._inner_indexer(lvals, rvals)[0]

    other_uniq = other.unique()
    indexer = other_uniq.get_indexer(lvals)
    indexer = indexer.take((indexer != -1).nonzero()[0])

    return other_uniq.take(indexer)._ndarray_values

def mixed(self, other):
    lvals = self._ndarray_values
    rvals = other._ndarray_values

    if self.is_monotonic and other.is_monotonic:
        return self._inner_indexer(lvals, rvals)[0]

    other_uniq = set(rvals)
    seen = set()
    return [x for x in lvals if x in other_uniq and not (x in seen or seen.add(x))]

size = 100000 
left = pd.MultiIndex.from_arrays([np.arange(1, size), np.arange(1, size)])
right = pd.MultiIndex.from_arrays([np.arange(1, size//10)[::-1], np.arange(1, size//10)[::-1]])
right_monotonic = pd.MultiIndex.from_arrays([np.arange(1, size//10), np.arange(1, size//10)])

for r in [right, right_monotonic]:
    print(f"\nBoth monotonic: {r.is_monotonic}\n---------------")
    expected = pd.MultiIndex.from_tuples(pr(left, r))
    actual_indexer = pd.MultiIndex.from_tuples(indexer(left, r))
    assert_index_equal(expected, actual_indexer)
    actual_mixed = pd.MultiIndex.from_tuples(mixed(left, r))
    assert_index_equal(expected, actual_mixed)

    print("master implementation:")
    %timeit -n 10 master(left, r)
    print("pr implementation:")
    %timeit -n 10 pr(left, r)
    print("Suggested indexer implementation:")
    %timeit -n 10 indexer(left, r)
    print("Mixed implementation:")
    %timeit -n 10 mixed(left, r)