Numpy常用函数总结

Numpy函数

  • 广播
  • 数学函数
    • 算术运算
      • 加:numpy.add(x1, x2, *args, **kwargs)
      • 减:numpy.subtract(x1, x2, *args, **kwargs)
      • 乘:numpy.multiply(x1, x2, *args, **kwargs)
      • 除:numpy.divide(x1, x2, *args, **kwargs)
      • 整除:numpy.floor_divide(x1, x2, *args, **kwargs)
      • 幂:numpy.power(x1, x2, *args, **kwargs)
      • 开方:numpy.sqrt(x, *args, **kwargs)
      • 平方:numpy.square(x, *args, **kwargs)
      • 示例
    • 三角函数
      • numpy.sin(x, *args, **kwargs)
      • numpy.cos(x, *args, **kwargs)
      • numpy.tan(x, *args, **kwargs)
      • numpy.arcsin(x, *args, **kwargs)
      • numpy.arccos(x, *args, **kwargs)
      • numpy.arctan(x, *args, **kwargs)
      • 示例
    • 指数、对数函数
      • numpy.exp(x, *args, **kwargs)
      • numpy.log(x, *args, **kwargs)
      • numpy.exp2(x, *args, **kwargs)
      • numpy.log2(x, *args, **kwargs)
      • numpy.log10(x, *args, **kwargs)
      • 示例
    • 维度加、累加、累乘
      • 维度加:numpy.sum(a[, axis=None, dtype=None, out=None, …])—— 返回给定轴上的数组元素的总和
      • 累加:numpy.cumsum(a, axis=None, dtype=None, out=None) ——返回给定轴上的数组元素的累加和。
      • 维度乘:numpy.prod(a[, axis=None, dtype=None, out=None, …])—— 返回给定轴上数组元素的乘积
      • 累乘:numpy.cumprod(a, axis=None, dtype=None, out=None) ——返回给定轴上数组元素的累乘
    • 临差:numpy.diff(a, n=1, axis=-1, prepend=np._NoValue, append=np._NoValue) — 沿着指定轴计算第N维的离散差值
    • 四舍五入
      • numpy.around(a, decimals=0, out=None) —— 将数组舍入到给定的小数位数
      • 向上\下取整
        • numpy.ceil(x, *args, **kwargs)——向上取整
        • numpy.floor(x, *args, **kwargs) ——向下取整
    • 其它
      • numpy.clip(a, a_min, a_max, out=None, **kwargs) —— 限制值范围
      • numpy.absolute(x, *args, **kwargs) /numpy.abs(x, *args, **kwargs) —— 绝对值
      • numpy.sign(x, *args, **kwargs) ——正负性返回
  • 逻辑函数
    • 真值判断numpy.all(任意真则真)、numpy.any(存在真则真)
    • 逻辑运算
      • 与、或、非、异或
        • numpy.logical_and(x1, x2, *args, **kwargs)
        • numpy.logical_or(x1, x2, *args, **kwargs)
        • numpy.logical_not(x, *args, **kwargs)
        • numpy.logical_xor(x1, x2, *args, **kwargs)
      • 比较(大于、小于、等于、不大于、不小于)
        • numpy.greater(x1, x2, *args, **kwargs)
        • numpy.greater_equal(x1, x2, *args, **kwargs)
        • numpy.equal(x1, x2, *args, **kwargs)
        • numpy.not_equal(x1, x2, *args, **kwargs)
        • numpy.less(x1, x2, *args, **kwargs)
        • numpy.less_equal(x1, x2, *args, **kwargs)

广播

广播的规则有三个:

  • 如果两个数组的维度数dim不相同,那么小维度数组的形状将会在左边补1。

  • 如果shape维度不匹配,但是有维度是1,那么可以扩展维度是1的维度匹配另一个数组;

  • 如果shape维度不匹配,但是没有任何一个维度是1,则匹配引发错误;

    示例:

    x = np.arange(4)
    y = np.ones((3, 4))
    print(x.shape)  # (4,)
    print(y.shape)  # (3, 4)
    
    print((x + y).shape)  # (3, 4)
    print(x + y)
    # [[1. 2. 3. 4.]
    #  [1. 2. 3. 4.]
    #  [1. 2. 3. 4.]]
    

    shape维度不匹配,但是有维度是1:

    x = np.arange(4).reshape(4, 1)
    y = np.ones(5)
    
    print(x.shape)  # (4, 1)
    print(y.shape)  # (5,)
    
    print((x + y).shape)  # (4, 5)
    print(x + y)
    # [[1. 1. 1. 1. 1.]
    #  [2. 2. 2. 2. 2.]
    #  [3. 3. 3. 3. 3.]
    #  [4. 4. 4. 4. 4.]]
    
    x = np.array([0.0, 10.0, 20.0, 30.0])
    y = np.array([1.0, 2.0, 3.0])
    z = x[:, np.newaxis] + y
    print(z)
    # [[ 1.  2.  3.]
    #  [11. 12. 13.]
    #  [21. 22. 23.]
    #  [31. 32. 33.]]
    

    匹配失败:

    x = np.arange(4)
    y = np.ones(5)
    
    print(x.shape)  # (4,)
    print(y.shape)  # (5,)
    
    print(x + y)
    # ValueError: operands could not be broadcast together with shapes (4,) (5,)
    

数学函数

算术运算

算符为 元素级。也就是说,它们只用于位置相同的元素之间,所得到的运算结果组成一个新的数组。

加:numpy.add(x1, x2, *args, **kwargs)

Add arguments element-wise.

减:numpy.subtract(x1, x2, *args, **kwargs)

Subtract arguments element-wise

乘:numpy.multiply(x1, x2, *args, **kwargs)

Multiply arguments element-wise.

除:numpy.divide(x1, x2, *args, **kwargs)

Returns a true division of the inputs, element-wise.

整除:numpy.floor_divide(x1, x2, *args, **kwargs)

Return the largest integer smaller or equal to the division of the inputs.

幂:numpy.power(x1, x2, *args, **kwargs)

First array elements raised to powers from second array, element-wise.

开方:numpy.sqrt(x, *args, **kwargs)

Return the non-negative square-root of an array, element-wise.

平方:numpy.square(x, *args, **kwargs)

Return the element-wise square of the input.

示例

  • 矩阵与数字

    x = np.array([1, 2, 3, 4, 5, 6, 7, 8])
    y = x + 1
    print(y)
    print(np.add(x, 1))
    # [2 3 4 5 6 7 8 9]
    
    y = x - 1
    print(y)
    print(np.subtract(x, 1))
    # [0 1 2 3 4 5 6 7]
    
    y = x * 2
    print(y)
    print(np.multiply(x, 2))
    # [ 2  4  6  8 10 12 14 16]
    
    y = x / 2
    print(y)
    print(np.divide(x, 2))
    # [0.5 1.  1.5 2.  2.5 3.  3.5 4. ]
    
    y = x // 2
    print(y)
    print(np.floor_divide(x, 2))
    # [0 1 1 2 2 3 3 4]
    
    y = x ** 2
    print(y)
    print(np.power(x, 2))
    # [ 1  4  9 16 25 36 49 64]
    
  • 非相同形状矩阵运算(广播)

    x = np.array([[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]])
    
    y = np.arange(1, 6)
    print(y)
    # [1 2 3 4 5]
    
    z = x + y
    print(z)
    print(np.add(x, y))
    # [[12 14 16 18 20]
    #  [17 19 21 23 25]
    #  [22 24 26 28 30]
    #  [27 29 31 33 35]
    #  [32 34 36 38 40]]
    
    z = x - y
    print(z)
    print(np.subtract(x, y))
    # [[10 10 10 10 10]
    #  [15 15 15 15 15]
    #  [20 20 20 20 20]
    #  [25 25 25 25 25]
    #  [30 30 30 30 30]]
    
    z = x * y
    print(z)
    print(np.multiply(x, y))
    # [[ 11  24  39  56  75]
    #  [ 16  34  54  76 100]
    #  [ 21  44  69  96 125]
    #  [ 26  54  84 116 150]
    #  [ 31  64  99 136 175]]
    
    z = x / y
    print(z)
    print(np.divide(x, y))
    # [[11.          6.          4.33333333  3.5         3.        ]
    #  [16.          8.5         6.          4.75        4.        ]
    #  [21.         11.          7.66666667  6.          5.        ]
    #  [26.         13.5         9.33333333  7.25        6.        ]
    #  [31.         16.         11.          8.5         7.        ]]
    
    z = x // y
    print(z)
    print(np.floor_divide(x, y))
    # [[11  6  4  3  3]
    #  [16  8  6  4  4]
    #  [21 11  7  6  5]
    #  [26 13  9  7  6]
    #  [31 16 11  8  7]]
    
    z = x ** np.full([1, 5], 2)
    print(z)
    print(np.power(x, np.full([5, 5], 2)))
    # [[ 121  144  169  196  225]
    #  [ 256  289  324  361  400]
    #  [ 441  484  529  576  625]
    #  [ 676  729  784  841  900]
    #  [ 961 1024 1089 1156 1225]]
    
  • 相同形状代码运算

    x = np.array([[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]])
    
    y = np.arange(1, 26).reshape([5, 5])
    print(y)
    # [[ 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]]
    
    z = x + y
    print(z)
    print(np.add(x, y))
    # [[12 14 16 18 20]
    #  [22 24 26 28 30]
    #  [32 34 36 38 40]
    #  [42 44 46 48 50]
    #  [52 54 56 58 60]]
    
    z = x - y
    print(z)
    print(np.subtract(x, y))
    # [[10 10 10 10 10]
    #  [10 10 10 10 10]
    #  [10 10 10 10 10]
    #  [10 10 10 10 10]
    #  [10 10 10 10 10]]
    
    z = x * y
    print(z)
    print(np.multiply(x, y))
    # [[ 11  24  39  56  75]
    #  [ 96 119 144 171 200]
    #  [231 264 299 336 375]
    #  [416 459 504 551 600]
    #  [651 704 759 816 875]]
    
    z = x / y
    print(z)
    print(np.divide(x, y))
    # [[11.          6.          4.33333333  3.5         3.        ]
    #  [ 2.66666667  2.42857143  2.25        2.11111111  2.        ]
    #  [ 1.90909091  1.83333333  1.76923077  1.71428571  1.66666667]
    #  [ 1.625       1.58823529  1.55555556  1.52631579  1.5       ]
    #  [ 1.47619048  1.45454545  1.43478261  1.41666667  1.4       ]]
    
    z = x // y
    print(z)
    print(np.floor_divide(x, y))
    # [[11  6  4  3  3]
    #  [ 2  2  2  2  2]
    #  [ 1  1  1  1  1]
    #  [ 1  1  1  1  1]
    #  [ 1  1  1  1  1]]
    
    z = x ** np.full([5, 5], 2)
    print(z)
    print(np.power(x, np.full([5, 5], 2)))
    # [[ 121  144  169  196  225]
    #  [ 256  289  324  361  400]
    #  [ 441  484  529  576  625]
    #  [ 676  729  784  841  900]
    #  [ 961 1024 1089 1156 1225]]
    
  • 对每个元素开平方

    x = np.arange(1, 5)
    print(x)  # [1 2 3 4]
    #开方
    y = np.sqrt(x)
    print(y)
    # [1.         1.41421356 1.73205081 2.        ]
    print(np.power(x, 0.5))
    # [1.         1.41421356 1.73205081 2.        ]
    #平方
    y = np.square(x)
    print(y)
    # [ 1  4  9 16]
    print(np.power(x, 2))
    # [ 1  4  9 16]
    

三角函数

numpy.sin(x, *args, **kwargs)

Trigonometric sine, element-wise.

numpy.cos(x, *args, **kwargs)

Cosine element-wise.

numpy.tan(x, *args, **kwargs)

Compute tangent element-wise.

numpy.arcsin(x, *args, **kwargs)

Inverse sine, element-wise.

numpy.arccos(x, *args, **kwargs)

Trigonometric inverse cosine, element-wise.

numpy.arctan(x, *args, **kwargs)

Trigonometric inverse tangent, element-wise.

示例

x = np.linspace(start=0, stop=np.pi / 2, num=10)
print(x)
# [0.         0.17453293 0.34906585 0.52359878 0.6981317  0.87266463
#  1.04719755 1.22173048 1.3962634  1.57079633]

y = np.sin(x)
print(y)
# [0.         0.17364818 0.34202014 0.5        0.64278761 0.76604444
#  0.8660254  0.93969262 0.98480775 1.        ]

z = np.arcsin(y)
print(z)
# [0.         0.17453293 0.34906585 0.52359878 0.6981317  0.87266463
#  1.04719755 1.22173048 1.3962634  1.57079633]

y = np.cos(x)
print(y)
# [1.00000000e+00 9.84807753e-01 9.39692621e-01 8.66025404e-01
#  7.66044443e-01 6.42787610e-01 5.00000000e-01 3.42020143e-01
#  1.73648178e-01 6.12323400e-17]

z = np.arccos(y)
print(z)
# [0.         0.17453293 0.34906585 0.52359878 0.6981317  0.87266463
#  1.04719755 1.22173048 1.3962634  1.57079633]

y = np.tan(x)
print(y)
# [0.00000000e+00 1.76326981e-01 3.63970234e-01 5.77350269e-01
#  8.39099631e-01 1.19175359e+00 1.73205081e+00 2.74747742e+00
#  5.67128182e+00 1.63312394e+16]

z = np.arctan(y)
print(z)
# [0.         0.17453293 0.34906585 0.52359878 0.6981317  0.87266463
#  1.04719755 1.22173048 1.3962634  1.57079633]

指数、对数函数

numpy.exp(x, *args, **kwargs)

Calculate the exponential of all elements in the input array.

numpy.log(x, *args, **kwargs)

Natural logarithm, element-wise.

numpy.exp2(x, *args, **kwargs)

Calculate 2**p for all p in the input array.

numpy.log2(x, *args, **kwargs)

Base-2 logarithm of x.

numpy.log10(x, *args, **kwargs)

Return the base 10 logarithm of the input array, element-wise.

示例

x = np.arange(1, 5)
print(x)
# [1 2 3 4]
y = np.exp(x)
print(y)
# [ 2.71828183  7.3890561  20.08553692 54.59815003]
z = np.log(y)
print(z)
# [1. 2. 3. 4.]

维度加、累加、累乘

维度加:numpy.sum(a[, axis=None, dtype=None, out=None, …])—— 返回给定轴上的数组元素的总和

Sum of array elements over a given axis.
返回给定轴上的数组元素的总和。
通过不同的 axis,numpy 会沿着不同的方向进行操作:如果不设置,那么对所有的元素操作;如果axis=0,则沿着纵轴进行操作;axis=1,则沿着横轴进行操作;axis=i,则 numpy 沿着第i个下标变化的方向进行操作。
示例:

x = np.array([[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]])
y = np.sum(x)
print(y)  # 575

y = np.sum(x, axis=0)
print(y)  # [105 110 115 120 125]

y = np.sum(x, axis=1)
print(y)  # [ 65  90 115 140 165]

累加:numpy.cumsum(a, axis=None, dtype=None, out=None) ——返回给定轴上的数组元素的累加和。

Return the cumulative sum of the elements along a given axis.
聚合函数 是指对一组值(比如一个数组)进行操作,返回一个单一值作为结果的函数。因而,求数组所有元素之和的函数就是聚合函数。ndarray类实现了多个这样的函数。

x = np.array([[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]])
y = np.cumsum(x)
print(y)
# [ 11  23  36  50  65  81  98 116 135 155 176 198 221 245 270 296 323 351
#  380 410 441 473 506 540 575]

y = np.cumsum(x, axis=0)
print(y)
# [[ 11  12  13  14  15]
#  [ 27  29  31  33  35]
#  [ 48  51  54  57  60]
#  [ 74  78  82  86  90]
#  [105 110 115 120 125]]

y = np.cumsum(x, axis=1)
print(y)
# [[ 11  23  36  50  65]
#  [ 16  33  51  70  90]
#  [ 21  43  66  90 115]
#  [ 26  53  81 110 140]
#  [ 31  63  96 130 165]]

维度乘:numpy.prod(a[, axis=None, dtype=None, out=None, …])—— 返回给定轴上数组元素的乘积

Return the product of array elements over a given axis.
参数用法与numpy.sum()相同
示例:

x = np.array([[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]])
y = np.prod(x)
print(y)  # 788529152

y = np.prod(x, axis=0)
print(y)
# [2978976 3877632 4972968 6294624 7875000]

y = np.prod(x, axis=1)
print(y)
# [  360360  1860480  6375600 17100720 38955840]

累乘:numpy.cumprod(a, axis=None, dtype=None, out=None) ——返回给定轴上数组元素的累乘

Return the cumulative product of elements along a given axis.

x = np.array([[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]])
y = np.cumprod(x)
print(y)
# [         11         132        1716       24024      360360     5765760
#     98017920  1764322560  -837609728   427674624   391232512    17180672
#    395155456   893796352   870072320  1147043840   905412608  -418250752
#    755630080  1194065920 -1638662144  -897581056   444596224 -2063597568
#    788529152]

y = np.cumprod(x, axis=0)
print(y)
# [[     11      12      13      14      15]
#  [    176     204     234     266     300]
#  [   3696    4488    5382    6384    7500]
#  [  96096  121176  150696  185136  225000]
#  [2978976 3877632 4972968 6294624 7875000]]

y = np.cumprod(x, axis=1)
print(y)
# [[      11      132     1716    24024   360360]
#  [      16      272     4896    93024  1860480]
#  [      21      462    10626   255024  6375600]
#  [      26      702    19656   570024 17100720]
#  [      31      992    32736  1113024 38955840]]

临差:numpy.diff(a, n=1, axis=-1, prepend=np._NoValue, append=np._NoValue) — 沿着指定轴计算第N维的离散差值

The first difference is given by out[i] = a[i+1] - a[i] along the given axis, higher differences are calculated by using diff recursively.
Calculate the n-th discrete difference along the given axis

  • a:输入矩阵
  • n:可选,代表要执行几次差值
  • axis:默认是最后一个
    示例:
A = np.arange(2, 14).reshape((3, 4))
A[1, 1] = 8
print(A)
# [[ 2  3  4  5]
#  [ 6  8  8  9]
#  [10 11 12 13]]
print(np.diff(A))
# [[1 1 1]
#  [2 0 1]
#  [1 1 1]]
print(np.diff(A, axis=0))
# [[4 5 4 4]
#  [4 3 4 4]]

四舍五入

numpy.around(a, decimals=0, out=None) —— 将数组舍入到给定的小数位数

Evenly round to the given number of decimals

x = np.random.rand(3, 3) * 10
print(x)
# [[6.59144457 3.78566113 8.15321227]
#  [1.68241475 3.78753332 7.68886328]
#  [2.84255822 9.58106727 7.86678037]]

y = np.around(x)
print(y)
# [[ 7.  4.  8.]
#  [ 2.  4.  8.]
#  [ 3. 10.  8.]]

y = np.around(x, decimals=2)
print(y)
# [[6.59 3.79 8.15]
#  [1.68 3.79 7.69]
#  [2.84 9.58 7.87]]

向上\下取整

numpy.ceil(x, *args, **kwargs)——向上取整

Return the ceiling of the input, element-wise.

x = np.random.rand(3, 3) * 10
print(x)
# [[0.67847795 1.33073923 4.53920122]
#  [7.55724676 5.88854047 2.65502046]
#  [8.67640444 8.80110812 5.97528726]]

y = np.ceil(x)
print(y)
# [[1. 2. 5.]
#  [8. 6. 3.]
#  [9. 9. 6.]]

numpy.floor(x, *args, **kwargs) ——向下取整

Return the floor of the input, element-wise

y = np.floor(x)
print(y)
# [[0. 1. 4.]
#  [7. 5. 2.]
#  [8. 8. 5.]]

其它

numpy.clip(a, a_min, a_max, out=None, **kwargs) —— 限制值范围

Clip (limit) the values in an array

x = np.array([[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]])
y = np.clip(x, a_min=20, a_max=30)
print(y)
# [[20 20 20 20 20]
#  [20 20 20 20 20]
#  [21 22 23 24 25]
#  [26 27 28 29 30]
#  [30 30 30 30 30]]

numpy.absolute(x, *args, **kwargs) /numpy.abs(x, *args, **kwargs) —— 绝对值

abs是对absolute的简写形势

x = np.arange(-5, 5)
print(x)
# [-5 -4 -3 -2 -1  0  1  2  3  4]

y = np.abs(x)
print(y)
# [5 4 3 2 1 0 1 2 3 4]

y = np.absolute(x)
print(y)
# [5 4 3 2 1 0 1 2 3 4]

numpy.sign(x, *args, **kwargs) ——正负性返回

Returns an element-wise indication of the sign of a number.

x = np.arange(-5, 5)
print(x)
#[-5 -4 -3 -2 -1  0  1  2  3  4]
print(np.sign(x))
#[-1 -1 -1 -1 -1  0  1  1  1  1]

逻辑函数

真值判断numpy.all(任意真则真)、numpy.any(存在真则真)

  • numpy.all(a, axis=None, out=None, keepdims=np._NoValue) Test whether all array elements along a given axis evaluate to True.
  • numpy.any(a, axis=None, out=None, keepdims=np._NoValue) Test whether any array element along a given axis evaluates to True.
a = np.array([0, 4, 5])
b = np.copy(a)
print(np.all(a == b))  # True
print(np.any(a == b))  # True

b[0] = 1
print(np.all(a == b))  # False
print(np.any(a == b))  # True

print(np.all([1.0, np.nan]))  # True
print(np.any([1.0, np.nan]))  # True

a = np.eye(3)
print(np.all(a, axis=0))  # [False False False]
print(np.any(a, axis=0))  # [ True  True  True]

逻辑运算

与、或、非、异或

numpy.logical_and(x1, x2, *args, **kwargs)

Compute the truth value of x1 AND x2 element-wise.

numpy.logical_or(x1, x2, *args, **kwargs)

Compute the truth value of x1 OR x2 element-wise.

numpy.logical_not(x, *args, **kwargs)

Compute the truth value of NOT x element-wise.

numpy.logical_xor(x1, x2, *args, **kwargs)

Compute the truth value of x1 XOR x2, element-wise.

print(np.logical_not(3))  
# False
print(np.logical_not([True, False, 0, 1]))
# [False  True  True False]

x = np.arange(5)
print(np.logical_not(x < 3))
# [False False False  True  True]

【例】计算x1 AND x2元素的真值。

print(np.logical_and(True, False))  
# False
print(np.logical_and([True, False], [True, False]))
# [ True False]
print(np.logical_and(x > 1, x < 4))
# [False False  True  True False]

【例】逐元素计算x1 OR x2的真值。


print(np.logical_or(True, False))
# True
print(np.logical_or([True, False], [False, False]))
# [ True False]
print(np.logical_or(x < 1, x > 3))
# [ True False False False  True]

【例】计算x1 XOR x2的真值,按元素计算。

print(np.logical_xor(True, False))
# True
print(np.logical_xor([True, True, False, False], [True, False, True, False]))
# [False  True  True False]
print(np.logical_xor(x < 1, x > 3))
# [ True False False False  True]
print(np.logical_xor(0, np.eye(2)))
# [[ True False]
#  [False  True]]

比较(大于、小于、等于、不大于、不小于)

numpy.greater(x1, x2, *args, **kwargs)

Return the truth value of (x1 > x2) element-wise.

numpy.greater_equal(x1, x2, *args, **kwargs)

Return the truth value of (x1 >= x2) element-wise.

numpy.equal(x1, x2, *args, **kwargs)

Return (x1 == x2) element-wise.

numpy.not_equal(x1, x2, *args, **kwargs)

Return (x1 != x2) element-wise.

numpy.less(x1, x2, *args, **kwargs)

Return the truth value of (x1 < x2) element-wise.

numpy.less_equal(x1, x2, *args, **kwargs)

Return the truth value of (x1 =< x2) element-wise.

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

y = x > 2
print(y)
print(np.greater(x, 2))
# [False False  True  True  True  True  True  True]

y = x >= 2
print(y)
print(np.greater_equal(x, 2))
# [False  True  True  True  True  True  True  True]

y = x == 2
print(y)
print(np.equal(x, 2))
# [False  True False False False False False False]

y = x != 2
print(y)
print(np.not_equal(x, 2))
# [ True False  True  True  True  True  True  True]

y = x < 2
print(y)
print(np.less(x, 2))
# [ True False False False False False False False]

y = x <= 2
print(y)
print(np.less_equal(x, 2))
# [ True  True False False False False False False]

比较时可以存在广播

x = np.array([[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]])

np.random.seed(20200611)
y = np.random.randint(10, 50, 5)

print(y)
# [32 37 30 24 10]

z = x > y
print(z)
print(np.greater(x, y))
# [[False False False False  True]
#  [False False False False  True]
#  [False False False False  True]
#  [False False False  True  True]
#  [False False  True  True  True]]

z = x >= y
print(z)
print(np.greater_equal(x, y))
# [[False False False False  True]
#  [False False False False  True]
#  [False False False  True  True]
#  [False False False  True  True]
#  [False False  True  True  True]]

z = x == y
print(z)
print(np.equal(x, y))
# [[False False False False False]
#  [False False False False False]
#  [False False False  True False]
#  [False False False False False]
#  [False False False False False]]

z = x != y
print(z)
print(np.not_equal(x, y))
# [[ True  True  True  True  True]
#  [ True  True  True  True  True]
#  [ True  True  True False  True]
#  [ True  True  True  True  True]
#  [ True  True  True  True  True]]

z = x < y
print(z)
print(np.less(x, y))
# [[ True  True  True  True False]
#  [ True  True  True  True False]
#  [ True  True  True False False]
#  [ True  True  True False False]
#  [ True  True False False False]]

z = x <= y
print(z)
print(np.less_equal(x, y))
# [[ True  True  True  True False]
#  [ True  True  True  True False]
#  [ True  True  True  True False]
#  [ True  True  True False False]
#  [ True  True False False False]]

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