NumPy 函数 - sign(), signbit(), copysign()

2024年8月29日 | 阅读 10 分钟

大家好！我们已经知道 NumPy 包含许多非常方便的函数，用于在 Python 中执行数值运算。今天，让我们来学习一些名为 sign()、signbit() 和 copysign() 的函数。这些函数只能在 Python 中使用。在深入函数之前，让我简单介绍一下 NumPy 库或包。

Numpy

NumPy 由 Travis Oliphant 于 2005 年推出。他通过改进名为 Numarray 的旧模块或包创建了 NumPy，该包实际上被称为 Numeric Array。它主要用 C 语言编写。它有很多函数，可以使我们的工作更轻松。

随着数据科学的革命，NumPy、SciPy、Pandas 等数据分析库得到了显著扩展。Python 成为数据科学家首选的编程语言，因为它比其他语言的语法要简单得多。

NumPy 提供了一种简单有效的管理海量数据的方法。此外，NumPy 使矩阵乘法和数据操作变得极其简单。由于 NumPy 速度很快，因此非常适合处理大量数据。

以上就是关于 NumPy 库或包的内容。

现在，让我们来学习 NumPy 中的函数。

我们将使用的函数是：

sign()
signbit()
copysign()

Sign() 函数

sign() 是 NumPy 库中的一个函数。sign() 函数用于表示列表中或任何地方指定的数字的符号。现在，让我们来理解 sign() 函数的动态。

语法

输入参数

输入参数可以是：

数组
元组 (Tuples)
列表
整数值
浮点数值
双精度值

输出参数

输出参数取决于传递给 NumPy sign 参数的输入参数的类型。

输出值

如果给定值为正数且大于零，则输出值为 1。输入值是一个数字。该数字可以是整数或浮点值。

如果给定值为负数且小于零，则输出值为 -1。输入值是一个数字。该数字可以是整数或浮点值。

如果给定值为 0，则输出值为 0。零可以是 +0 / -0 / 0.0 / 任意值。

现在我们将了解 NumPy.sign 函数的工作原理。

示例 1

# This is a program wriiten to understand the working of the sign function in python Numpy Library

# Importing Numpy Library as np

import numpy as np 

# Creating a list with variable name l 

l = [1, -2, 5, -9, 0, 0.0, 1.0598, -0.597041, -0]

# Converting the list into an N Dimensional Array 
print("The Input Array is:")
arr = np.array(l)

print(arr)

# Using the sign function

sign = np. sign(arr)

# The Ouput value
print("The signs of the array arr is:")
print(sign)

输出

[ 1.       -2.        5.       -9.        0.        0.        1.0598   -0.597041  0.      ]
The sign of the array arr is:
[ 1. -1.  1. -1.  0.  0.  1. -1.  0.]

示例 2

''' This is a program written to understand the working of the sign function in python Numpy Library '''

# Importing Numpy Library as np

import numpy as np 

# Now we are taking an Integer as Input 

num  = int(input("Enter any Integer Number:"))
print("The Integer Number is:",num)
print("The sign value of %d is:"%num)
print(np.sign(num))
t1=np.sign(num)
print("The Output type of sign of num1 is",type(t1))
num2 = 0 
num3 = -1439
print("The sign value of %d is %d"%(num2, np.sign(num2)))
print("The sign value of %d is %d"%(num3, np.sign(num3)))


# Now we are taking list as input
l = [1, -2, 3, 0, 89, -6.23, 6.287, 0.04]
print("The list taken is:",l)

t = np.sign(l)
print("The Sign of list taken is:")
print(t)

print("The type of the Signed List is:",type(t))

# Now we are taking tuple as input
t =(8, 2, -6, 21, 0, -0.25, 8.25)
print("The Tuple taken is:",t)

ty = np.sign(t)

print("The sign of the tuple taken is:",ty)
print("The type of the Signed Tuple is:",type(ty))

# Now we are taking Complex Numbers as input
c1 = 1 + 0j
c2 = -1 + 5j
c3 = 6 + -2j
c4 = -6 - 6j
print("The Type of c1 is:",type(c1))
print("The Complex Number 1 is:",c1)
print("The Type of Complex Number 1 is:",np.sign(c1))
print("The Complex Number 2 is:",c2)
print("The Type of Complex Number 2 is:",np.sign(c2))
print("The Complex Number 3 is:",c3)
print("The Type of Complex Number 3 is:",np.sign(c3))
print("The Complex Number 4 is:",c4)
print("The Type of Complex Number 4 is:",np.sign(c4))

print("The type of sign of Complex Number:",type(np.sign(c3)))

输出

Enter any Integer Number:4
The Integer Number is: 4
The sign value of 4 is:
1
The Output type of sign of num1 is <class 'numpy.int64'>
The sign value of 0 is 0
The sign value of -1439 is -1
The list taken is: [1, -2, 3, 0, 89, -6.23, 6.287, 0.04]
The Sign of list taken is:
[ 1. -1.  1.  0.  1. -1.  1.  1.]
The type of the Signed List is: <class 'numpy.ndarray'>
The Tuple taken is:(8, 2, -6, 21, 0, -0.25, 8.25)
The sign of the tuple taken is: [ 1.  1. -1.  1.  0. -1.  1.]
The type of the Signed Tuple is: <class 'numpy.ndarray'>
The Type of c1 is: <class 'complex'>
The Complex Number 1 is:(1+0j)
The Type of Complex Number 1 is:(1+0j)
The Complex Number 2 is:(-1+5j)
The Type of Complex Number 2 is:(-1+0j)
The Complex Number 3 is:(6-2j)
The Type of Complex Number 3 is:(1+0j)
The Complex Number 4 is:(-6-6j)
The Type of Complex Number 4 is:(-1+0j)
The type of sign of Complex Number: <class 'numpy.complex128'>

示例 3

# This is a program written to understand the working of the sign function in python Numpy Library
import numpy as np

d = {1:1, 2:4, 3:9, 4:16}
print("The dictionary taken is:",d)

# Trying to know the sign of values in dictionary 
x = np.sign(d)
print(x)

输出

The dictionary taken is: {1: 1, 2: 4, 3: 9, 4: 16}
Traceback(most recent call last):
  File "main.py", line 8, in <module>
    x = np. sign(d)
TypeError: '<' not supported between instances of 'dict' and 'int'

从这个错误中，我们需要了解 NumPy 库中的 sign 函数不支持 Python 中的字典（Dictionary）和集合（Sets）。

以上就是 NumPy 库中 Sign() 函数的内容。

signbit() 函数

signbit() 是 NumPy 库中的一个函数。signbit() 函数用于表示列表中或任何地方指定的数字的负号。现在，让我们来理解 signbit() 函数的动态。

语法

输入参数

输入参数可以是：

数组
元组 (Tuples)
列表
整数值
浮点数值
双精度值

输出参数

输出参数取决于传递给 NumPy sign 参数的输入参数的类型。

signbit() 用于检查符号位是否已设置。

换句话说，我们可以说 signbit() 用于检查作为参数传递的数字是正数还是负数。

如果作为参数传递的数字大于或等于零，则输出为 False。

如果作为参数传递的数字小于零，则输出为 True。

这是 signbit() 函数的基本概述。

示例 1

''' This is a program written to understand the working of the sign function in python Numpy Library '''

# Importing Numpy Library as np

import numpy as np 

# Let us take Positive Integer number as an Input 

num = 100 
print("The Number taken is:",num)
x = np.signbit(num)
print("The statement whether signbit of the number is set or not: ",x)

print("The type of x is:",type(x))
print()

# Let us take Zero Integer number as an Input 

num1 =  0
print("The Number taken is:",num1)
x = np.signbit(num1)
print("The statement whether signbit of the number is set or not: ",x)

print("The type of x is:",type(x))
print()

# Let us take Negative Integer number as an Input 

num2 = -45100 
print("The Number taken is:",num2)
x = np.signbit(num2)
print("The statement whether signbit of the number is set or not: ",x)

print("The type of x is:",type(x))

输出

The Number taken is: 100
The statement whether signbit of the number is set or not:  False
The type of x is: <class 'numpy.bool_'>

The Number taken is: 0
The statement whether signbit of the number is set or not:  False
The type of x is: <class 'numpy.bool_'>

The Number taken is: -45100
The statement whether signbit of the number is set or not:  True
The type of x is: <class 'numpy.bool_'>

示例 2

''' This is a program written to understand the working of the signbit function in python Numpy Library '''

# Importing Numpy Library as np

import numpy as np 

# Now we are taking an Integer as Input 

num  = int(input("Enter any Integer Number:"))
print("The Integer Number is:",num)
print("The sign value of %d is:"%num)
print(np.signbit(num))
t1 = np.signbit(num)
print("The Output type of sign of num1 is",type(t1))
num2 = 0 
num3 = -1439
print("The signbit value of %d is %d"%(num2, np.signbit(num2)))
print("The signbit value of %d is %d"%(num3, np.signbit(num3)))
print()

# Now we are taking list as input
l = [1, -2, 3, 0, 89, -6.23, 6.287, 0.04]
print("The list taken is:",l)

t = np.signbit(l)
print("The Signbit Values of list taken is:")
print(t)

print("The type of the SignBit List is:",type(t))
print()

# Now we are taking tuple as input
t =(8, 2, -6, 21, 0, -0.25, 8.25)
print("The Tuple taken is:",t)

ty = np.signbit(t)

print("The signbit Values of the tuple taken is:",ty)
print("The type of the SignBit Tuple is:",type(ty))

输出

Enter any Integer Number:75
The Integer Number is: 75
The Sign Bit value of 75 is:
False
The Output type of sign of num1 is <class 'numpy.bool_'>
The Sign Bit value of 0 is 0
The Sign Bit value of -1439 is 1

The list taken is: [1, -2, 3, 0, 89, -6.23, 6.287, 0.04]
The Sign Bit Values of list taken is:
[False  True False False False  True False False]
The type of the Sign Bit List is: <class 'numpy.ndarray'>

The Tuple taken is:(8, 2, -6, 21, 0, -0.25, 8.25)
The Sign Bit Values of the tuple taken is: [False False  True False False  True False]
The type of the Sign Bit Tuple is: <class 'numpy.ndarray'>

同样，此函数也不支持字典和集合数据结构。

copysign() 函数

copysign() 是 NumPy 库中的一个函数。copysign() 函数用于表示列表中或任何地方指定的数字的负号。现在，让我们来理解 copysign() 函数的动态。

语法

输入参数

输入参数可以是：

数组
元组 (Tuples)
列表
整数值
浮点数值
双精度值

输出参数

输出参数取决于传递给 NumPy sign 参数的输入参数的类型。

此过程的主要功能是将值 2 的符号位交换到值 1。

请查看示例以了解 copysign() 函数的动态。

示例 1

''' This is a program written to understand the working of the Copy Sign function in python Numpy Library '''

# Importing Numpy Library as np

import numpy as np 

# Now we are taking an Integer as Input 

n1 = 10 
n2 = -1 
print("The First Integer taken is: ",n1)
print("The Second Integer taken is: ",n2)
print("The Sign Bit of n1 is ", np.signbit(n1))
print("The Sign Bit of n2 is", np.signbit(n2))

x = np.copysign(n1,n2)
print("The changed number after using Copy Sign is: ",x)

print("The Sign Bit of Changed Number is:", np.signbit(x))

print("The type of Changed Number is:", type(x))

print()
# Now we are taking Lists as an Input 

l1 = [1, -2, 3 ,-4]
l2 = [-5 , 6, -7, 8]
print("The First List taken is: ",l1)
print("The Second List taken is: ",l2)
print("The Sign Bits of l1 is ", np.signbit(l1))
print("The Sign Bits of l2 is", np.signbit(l2))
x = np.copysign(l1,l2)
print("The changed list after using Copy Sign is: ",x)

print("The Sign Bit of Changed List is:", np.signbit(x))

print("The type of Changed Number is:", type(x))

print()

# Now we are taking Tuples as an Input 

t1 =(-1, 2, -3 ,4)
t2 =(5 , -6, 7, -8)
print("The First List taken is: ",t1)
print("The Second List taken is: ",t2)
print("The Sign Bits of t1 is ", np.signbit(t1))
print("The Sign Bits of t2 is", np.signbit(t2))
x = np.copysign(t1,t2)
print("The changed Tuple after using Copy Sign is: ",x)

print("The Sign Bit of Changed List is:", np.signbit(x))

print("The type of Changed Number is:", type(x))

print()

输出

The First Integer taken is:  10
The Second Integer taken is:  -1
The Sign Bit of n1 is  False
The Sign Bit of n2 is True
The changed number after using Copy Sign is:  -10.0
The Sign Bit of Changed Number is: True
The type of Changed Number is: <class 'numpy.float64'>

The First List taken is:  [1, -2, 3, -4]
The Second List taken is:  [-5, 6, -7, 8]
The Sign Bits of l1 is  [False  True False  True]
The Sign Bits of l2 is [ True False  True False]
The changed list after using Copy Sign is:  [-1.  2. -3.  4.]
The Sign Bit of Changed List is: [ True False  True False]
The type of Changed Number is: <class 'numpy.ndarray'>

The First List taken is: (-1, 2, -3, 4)
The Second List taken is: (5, -6, 7, -8)
The Sign Bits of t1 is  [ True False  True False]
The Sign Bits of t2 is [False  True False  True]
The changed Tuple after using Copy Sign is:  [ 1. -2.  3. -4.]
The Sign Bit of Changed List is: [False  True False  True]
The type of Changed Number is: <class 'numpy.ndarray'>

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