python_ebook/NumPy/Code/ch2code/arrayattributes2.py at master · WilliamMKLee/python_ebook · GitHub

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import numpy as np

# Chapter 2 Beginning with NumPy fundamentals
#
# Demonstrates ndarray attributes.
#
# Run from the commandline with
#
#  python arrayattributes2.py
b = np.arange(24).reshape(2, 12)
print "In: b"
print b
#Out:
#array([[ 0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11],
#       [12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23]])

print "In: b.ndim"
print b.ndim
#Out: 2

print "In: b.size"
print b.size
#Out: 24

print "In: b.itemsize"
print b.itemsize
#Out: 8

print "In: b.nbytes"
print b.nbytes
#Out: 192

print "In: b.size * b.itemsize"
print b.size * b.itemsize
#Out: 192

print "In: b.resize(6,4)"
print b.resize(6,4)

print "In: b"
print b
#Out:
#array([[ 0,  1,  2,  3],
#       [ 4,  5,  6,  7],
#       [ 8,  9, 10, 11],
#       [12, 13, 14, 15],
#       [16, 17, 18, 19],
#       [20, 21, 22, 23]])

print "In: b.T"
print b.T
#Out:
#array([[ 0,  4,  8, 12, 16, 20],
#       [ 1,  5,  9, 13, 17, 21],
#       [ 2,  6, 10, 14, 18, 22],
#       [ 3,  7, 11, 15, 19, 23]])

print "In: b.ndim"
print b.ndim
#Out: 1

print "In: b.T"
print b.T
#Out: array([0, 1, 2, 3, 4])


print "In: b = array([1.j + 1, 2.j + 3])"
b = np.array([1.j + 1, 2.j + 3])

print "In: b"
print b
#Out: array([ 1.+1.j,  3.+2.j])

print "In: b.real"
print b.real
#Out: array([ 1.,  3.])

print "In: b.imag"
print b.imag
#Out: array([ 1.,  2.])

print "In: b.dtype"
print b.dtype
#Out: dtype('complex128')

print "In: b.dtype.str"
print b.dtype.str
#Out: '<c16'


print "In: b = arange(4).reshape(2,2)"
b = np.arange(4).reshape(2,2)

print "In: b"
print b
#Out:
#array([[0, 1],
#       [2, 3]])

print "In: f = b.flat"
f = b.flat

print "In: f"
print f
#Out: <numpy.flatiter object at 0x103013e00>

print "In: for it in f: print it"
for it in f:
   print it
#0
#1
#2
#3

print "In: b.flat[2]"
print b.flat[2]
#Out: 2


print "In: b.flat[[1,3]]"
print b.flat[[1,3]]
#Out: array([1, 3])


print "In: b"
print b
#Out:
#array([[7, 7],
#       [7, 7]])

print "In: b.flat[[1,3]] = 1"
b.flat[[1,3]] = 1

print "In: b"
print b
#Out:
#array([[7, 1],
#       [7, 1]])