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How to Get the Sign of an Integer in Python?
Python Integers are one of the primary data types, and are used for almost all major mathematical and logical operations. In Python, integers are zero,positive or negative whole numbers without a fractional part and having unlimited precision.They can be expressed in binary, octal and hexadecimal values. In this article, we will learn how to obtain the sign of an integer.
Using simple mathematical comparison with zero
Using copysign() function of math module
Using numpy.sign() function
Creating a method with abs() function
Method 1: Using Mathematical Comparison with Zero
We can use the basic mathematical definition of positive and negative numbers to find the sign of a given integer. We use a basic if-else structure to determine the sign of a number.
if number>0 return 1 else if number<0 return -1 else return 0
In this method, we use a cascaded if-else-if structure to create a decisionmaking point at the point zero in the number line of integers. If the number input by the user is greater than zero, the program returns +1, if it is less than zero, the program returns -1 and if it’s zero, the program returns zero as the answer.
Step 1 − Take the user input for the integer for which sign is to be determined
Step 2 − Create an ‘if’ with the initial condition that if the input number is greater than zero, the function returns 1
Step 3 − Create a cascading ‘else-if’ condition which returns -1 if the input number is less than zero
Step 4 − Create a final ‘else’ condition where the function returns zero if the input number is zero
def solution(number): if (number>0): return 1 elif (number<0): return -1 else: return 0 val =-2 sol = solution(val) print(sol)
Method 2: Using copysign() Function of Math Module
The copysign() function in the math module returns the value of the first argument with the sign of the second argument. Hence we use 1 in place of the first argument to find the sign of the input integer placed as the second argument. This function can handle values of integers,floating point numbers as well as positive and negative nan.
To perform this operation, we need to call the copysign function. As arguments, we need to pass two numbers, from which the magnitude of the first number and the sign of the second number is returned by the function as a single number.
Step 1 − Import the math module
Step 2 − Take the input integer from the user for which sign is to be determined
Step 3 − Pass the integer as the second argument in the copysign() function, according to the given syntax
import math def solution(number): return int(math.copysign(1,number)) val = -2 sol = solution(val) print(sol)
Method 3: Using numpy.sign() Function
The numpy module provides a sign() function which can be used to determine the sign of an integer. This is pretty useful as there isn’t any sign() function by default in the math library of Python. It can be used on an entire array of integers to display the sign element-wise.
numpy.sign(array , out)
The syntax is pretty simple, it calls the sign function and passes two arguments. Only the first argument is compulsory, the second one is optional.The first argument passes the array of elements, the second argument is output array placed with the result.
Step 1 − Import the numpy module
Step 2 − Take input elements in the array for which sign(s) are required to be determined
Step 3 − Call the sign() function and pass the array containing the target elements
Step 4 − Display the output values i.e. the signs of the integers
import numpy as user #importing numpy array=[25, -25, 0] #input array print("input array : ", array) #input array with elements print("Check sign of array : ", user.sign(array)) #signs of elements
input array: [25 -25 0] Check sign of array: [1 -1 0]
Method 4: Creating a Method with abs() Function
We can use the abs() function to define a sign function which returns the sign of the integer. The abs() function returns the absolute value of a number.
Here we divide the integer with its absolute value to find the sign of the integer. As we divide two integers here, the function returns a float value, however it works for integers.
Step 1 − Define a function
Step 2 − Pass the number to the function whose sign is to be determined as an argument
Step 3 − Create an ‘if-else’ structure to check if input integer is zero
Step 4 − Display the output value by dividing the integer with its absolute value
def int_sign(x): if (x==0): return 0 else: return x/abs(x) num=-2 print(int_sign(num))
In this article, we have talked about some ways in which we can find the sign of an integer supplied by the user or set in the program. This article is usually written keeping Python in mind, however similar methods are also available in different programming languages.
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