python & numpy port of james hague's blog post 141

prog21_141.py

"""
python & numpy port of james hague's blog post 141

ref:
    http://prog21.dadgum.com/141.html
"""

import numpy

a = numpy.array([10, 5, 9, 6, 20, 17, 1])
print(a)

# slice into `a` using array of indices
print(a[[0, 1, 3, 6]])

# drop first two elements, slicing with explicit array of indices
print(a[[2, 3, 4, 5, 6]])

# drop first two elements, slicing with boolean mask array
print(a[numpy.array([False, False, True, True, True, True, True], dtype = numpy.bool)])

# drop first two elements using nice pythonic slice syntax
print(a[2:])

# permute arrays `a` and `b` to sort a, keeping them in synch
b = numpy.array([101, 51, 91, 61, 201, 171, 11])
print(a)
print(b)
order = numpy.argsort(a)
# check that argsort does what we expect
assert numpy.all(a[order] == numpy.sort(a))
print(a[order])
print(b[order])