numpy where with array of tuples

问题

Why can't I find the location of a tuple in an array? Afterall, the bottom expression prints True

foo = numpy.array([(5, 30), (5,), 5])
bar = numpy.where(foo==foo[0])
print(bar)

Prints (array([], dtype=int64),)

print((5,30)==foo[0])

Prints True

回答1:

It's because:

import numpy

foo = numpy.array([(5, 30), (5,), 5])
bar = numpy.where(foo==foo[0])
print(foo==foo[0])

False

That's why you're getting an empty array. A list comprehension alternative is [v for v in foo if v == foo[0]] will result in [(5, 30)]

来源：https://stackoverflow.com/questions/33609871/numpy-where-with-array-of-tuples