python numpy数组

1.数组创建:

import numpy

arr = numpy.array([11, 22, 33, 44, 55])

print(arr)
输出:
[11 22 33 44 55]
#数组属性查看:
print(type(arr))
输出:
<class 'numpy.ndarray'>
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2.数组维度:

import numpy

arr = numpy.array(10)
arr1 = numpy.array([1, 2, 3, 4, 5])
arr2 = numpy.array((1,2,3,4,5))
arr3 = numpy.array([[8,9,10],[1,2,3],[4,5,6]])

#查看维度数:
print(arr)
print(arr1)
print(arr2)
print(arr3)
输出:
	0
	1
	1
	2
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3.数组索引:

import numpy

arr = numpy.array([1,2,3,4,5])
arr1 = numpy.array([[11,22],[33,44],[55,66]])

print(arr[3])
输出:
	4
print(arr11[2,1])
输出: 
    66
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4.数组迭代:

import numpy

arr = numpy.array([11,22,33])
for i in arr:
    print(i)
输出:
     11
     22
     33
arr0 = numpy.array([[[1, 2, 3], [4, 5, 6]], [[7, 8, 9], [10, 11, 12]]])
for x in arr0:
  print(x)
  for y in x:
      print(y)
      for z in y:
          print(z)
输出:
[1 2 3]
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3
[4 5 6]
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6
[[ 7  8  9]
 [10 11 12]]
[7 8 9]
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9
[10 11 12]
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12
for k in numpy.nditer(arr0):
    print(k)
    输出:
    1
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	5
	6
	7
	8
	9
	10
	11
	12
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5.数组随机取数:

from numpy import random

 #整数分3组5个
x = random.randint(100,size=(3,5))  
#浮点数分3组5个       
y = random.rand(3,5)                        
z = random.choice([11,22,33])   

print(x)
输出:
[[83 28 58 86 28]
 [74 10 50 64 77]
 [74 47 72 52 69]]
print(y)
输出:
[[0.62403419 0.28132926 0.39252042 0.24294266 0.32071179]
 [0.00681339 0.22880091 0.96694071 0.72081899 0.52969825]
 [0.89168273 0.44716415 0.97038642 0.39105253 0.58724623]]
print(z)
输出:
     22
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6.数组合并:

import numpy
arr8 = numpy.array([[1, 2, 3],[7,8,9]])
arr9 = numpy.array([[4, 5, 6],[10,11,12]])
arr10 = numpy.array([[4, 7, 6],[10,17,12]])


print(numpy.concatenate((arr8,arr9),axis=1)) 
输出:
[[ 1  2  3  4  5  6]
 [ 7  8  9 10 11 12]]   
print(numpy.stack((arr8,arr9),axis=1))   
输出:
   [[[ 1  2  3]
  [ 4  5  6]]

 [[ 7  8  9]
  [10 11 12]]]           
print(numpy.vstack((arr8,arr9))) 
输出:
[[ 1  2  3]
 [ 7  8  9]
 [ 4  5  6]
 [10 11 12]]                      
print(numpy.dstack((arr8,arr9)))                        
输出:
[[[ 1  4]
  [ 2  5]
  [ 3  6]]

 [[ 7 10]
  [ 8 11]
  [ 9 12]]]
print(numpy.concatenate((arr8,arr9)))    
输出:
[[ 1  2  3]
 [ 7  8  9]
 [ 4  5  6]
 [10 11 12]]               
print(numpy.hstack((arr8,arr9)))   
输出:
[[ 1  2  3  4  5  6]
 [ 7  8  9 10 11 12]]
 
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7.数组拆分:

import numpy

arr = numpy.array([1,2,3,4,5,6,7,8])

print(numpy.array_split(arr,2))
输出:
[array([1, 2, 3, 4]), array([5, 6, 7, 8])]
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8.数组过滤、排序:

import numpy

arr = numpy.array([1,2,3,4,5,6,7,8])
new_arr = []
for i in arr:
    if i%2 == 0:
        new_arr.append(True)
    else:
        new_arr.append(False)

N_arr = arr[new_arr]

print(new_arr)
print(N_arr)

输出:
[False, True, False, True, False,rue, False, True]
[2 4 6 8]

arr0 = numpy.array([[4, 7, 6],[10,17,12]])

print(numpy.sort(arr0))   
输出:
 [[ 4  6  7]
  [10 12 17]]]
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