数组的合并¶

In [3]:

a = np.array([[1, 2,3], [7, 8, 9]])
b = np.array([[100, 101, 102], [103, 104, 105]])
c = np.array([[0,0], [0, 0]])

In [4]:

a
b
c

Out[4]:

array([[1, 2, 3],
       [7, 8, 9]])

Out[4]:

array([[100, 101, 102],
       [103, 104, 105]])

Out[4]:

array([[0, 0],
       [0, 0]])

np.vstack 沿纵轴拼接¶

在纵向拼接，增加的是行，列不变

In [5]:

np.vstack((a,b))

Out[5]:

array([[  1,   2,   3],
       [  7,   8,   9],
       [100, 101, 102],
       [103, 104, 105]])

In [6]:

np.vstack((a,c))   #维度必须匹配

---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
<ipython-input-6-abd99944b1f4> in <module>
----> 1 np.vstack((a,c))   #维度必须匹配

D:\Anaconda3\lib\site-packages\numpy\core\shape_base.py in vstack(tup)
    281     """
    282     _warn_for_nonsequence(tup)
--> 283     return _nx.concatenate([atleast_2d(_m) for _m in tup], 0)
    284 
    285 

ValueError: all the input array dimensions except for the concatenation axis must match exactly

np.hstack 沿横轴拼接¶

在横向拼接，增加的是列，行不变

In [7]:

a = np.array([[1, 2,3], [7, 8, 9]])
b = np.array([[100, 101, 102], [103, 104, 105]])
c = np.array([[0,0], [0, 0]])

In [8]:

a
b
c

Out[8]:

array([[1, 2, 3],
       [7, 8, 9]])

Out[8]:

array([[100, 101, 102],
       [103, 104, 105]])

Out[8]:

array([[0, 0],
       [0, 0]])

In [9]:

np.hstack((a,b))

Out[9]:

array([[  1,   2,   3, 100, 101, 102],
       [  7,   8,   9, 103, 104, 105]])

In [10]:

np.hstack((a,c))

Out[10]:

array([[1, 2, 3, 0, 0],
       [7, 8, 9, 0, 0]])

指定拼接方向的np.concatenate()¶

参数axis=0默认在纵轴上拼接，axis=1横向拼接

In [11]:

a = np.array([[1, 2,3], [7, 8, 9]])
b = np.array([[100, 101, 102], [103, 104, 105]])
c = np.array([[0,0], [0, 0]])

In [12]:

a
b
c

Out[12]:

array([[1, 2, 3],
       [7, 8, 9]])

Out[12]:

array([[100, 101, 102],
       [103, 104, 105]])

Out[12]:

array([[0, 0],
       [0, 0]])

In [13]:

np.concatenate((a,b), axis=0)   #axis=0默认在纵轴上拼接

Out[13]:

array([[  1,   2,   3],
       [  7,   8,   9],
       [100, 101, 102],
       [103, 104, 105]])

In [14]:

np.concatenate((a,b), axis=1)   #axis=1在横轴上拼接

Out[14]:

array([[  1,   2,   3, 100, 101, 102],
       [  7,   8,   9, 103, 104, 105]])

In [ ]:

数组的分割¶

In [15]:

a = np.arange(1,37).reshape(4,9)
a

Out[15]:

array([[ 1,  2,  3,  4,  5,  6,  7,  8,  9],
       [10, 11, 12, 13, 14, 15, 16, 17, 18],
       [19, 20, 21, 22, 23, 24, 25, 26, 27],
       [28, 29, 30, 31, 32, 33, 34, 35, 36]])

np.hsplit 横向进行分割¶

In [16]:

b = np.hsplit(a,3)    # 第二个参数只写一个整数时，会在横向进行平均分割
b

Out[16]:

[array([[ 1,  2,  3],
        [10, 11, 12],
        [19, 20, 21],
        [28, 29, 30]]), array([[ 4,  5,  6],
        [13, 14, 15],
        [22, 23, 24],
        [31, 32, 33]]), array([[ 7,  8,  9],
        [16, 17, 18],
        [25, 26, 27],
        [34, 35, 36]])]

In [17]:

for i in b:
    print(i)
    print('*'*30)

[[ 1  2  3]
 [10 11 12]
 [19 20 21]
 [28 29 30]]
******************************
[[ 4  5  6]
 [13 14 15]
 [22 23 24]
 [31 32 33]]
******************************
[[ 7  8  9]
 [16 17 18]
 [25 26 27]
 [34 35 36]]
******************************

In [18]:

Out[18]:

array([[ 1,  2,  3,  4,  5,  6,  7,  8,  9],
       [10, 11, 12, 13, 14, 15, 16, 17, 18],
       [19, 20, 21, 22, 23, 24, 25, 26, 27],
       [28, 29, 30, 31, 32, 33, 34, 35, 36]])

In [19]:

np.hsplit(a,(3,5))   #在第三列和第五列的后面划一刀

Out[19]:

[array([[ 1,  2,  3],
        [10, 11, 12],
        [19, 20, 21],
        [28, 29, 30]]), array([[ 4,  5],
        [13, 14],
        [22, 23],
        [31, 32]]), array([[ 6,  7,  8,  9],
        [15, 16, 17, 18],
        [24, 25, 26, 27],
        [33, 34, 35, 36]])]

In [20]:

np.hsplit(a,(3,5,6,7)) 

Out[20]:

[array([[ 1,  2,  3],
        [10, 11, 12],
        [19, 20, 21],
        [28, 29, 30]]), array([[ 4,  5],
        [13, 14],
        [22, 23],
        [31, 32]]), array([[ 6],
        [15],
        [24],
        [33]]), array([[ 7],
        [16],
        [25],
        [34]]), array([[ 8,  9],
        [17, 18],
        [26, 27],
        [35, 36]])]

np.vsplit()横向进行分割¶

In [21]:

Out[21]:

array([[ 1,  2,  3,  4,  5,  6,  7,  8,  9],
       [10, 11, 12, 13, 14, 15, 16, 17, 18],
       [19, 20, 21, 22, 23, 24, 25, 26, 27],
       [28, 29, 30, 31, 32, 33, 34, 35, 36]])

In [22]:

np.vsplit(a,4)

Out[22]:

[array([[1, 2, 3, 4, 5, 6, 7, 8, 9]]),
 array([[10, 11, 12, 13, 14, 15, 16, 17, 18]]),
 array([[19, 20, 21, 22, 23, 24, 25, 26, 27]]),
 array([[28, 29, 30, 31, 32, 33, 34, 35, 36]])]

In [23]:

np.vsplit(a,(1,3))

Out[23]:

[array([[1, 2, 3, 4, 5, 6, 7, 8, 9]]),
 array([[10, 11, 12, 13, 14, 15, 16, 17, 18],
        [19, 20, 21, 22, 23, 24, 25, 26, 27]]),
 array([[28, 29, 30, 31, 32, 33, 34, 35, 36]])]

可指定方向的np.array_split()¶

In [24]:

Out[24]:

array([[ 1,  2,  3,  4,  5,  6,  7,  8,  9],
       [10, 11, 12, 13, 14, 15, 16, 17, 18],
       [19, 20, 21, 22, 23, 24, 25, 26, 27],
       [28, 29, 30, 31, 32, 33, 34, 35, 36]])

In [25]:

np.array_split(a,(1,3),axis=0)

Out[25]:

[array([[1, 2, 3, 4, 5, 6, 7, 8, 9]]),
 array([[10, 11, 12, 13, 14, 15, 16, 17, 18],
        [19, 20, 21, 22, 23, 24, 25, 26, 27]]),
 array([[28, 29, 30, 31, 32, 33, 34, 35, 36]])]

In [26]:

np.array_split(a,(1,3),axis=1)

Out[26]:

[array([[ 1],
        [10],
        [19],
        [28]]), array([[ 2,  3],
        [11, 12],
        [20, 21],
        [29, 30]]), array([[ 4,  5,  6,  7,  8,  9],
        [13, 14, 15, 16, 17, 18],
        [22, 23, 24, 25, 26, 27],
        [31, 32, 33, 34, 35, 36]])]

In [ ]:

Table of Contents

数组的合并¶

np.vstack 沿纵轴拼接¶

np.hstack 沿横轴拼接¶

指定拼接方向的np.concatenate()¶

数组的分割¶

np.hsplit 横向进行分割¶

np.vsplit()横向进行分割¶

可指定方向的np.array_split()¶