How to get numbers in python
This is more than a bit late, but you can extend the regex expression to account for scientific notation too. Show
Gives all good! Additionally, you can look at the AWS Glue built-in regex View Discussion Improve Article Save Article View Discussion Improve Article Save Article Many times, while working with strings we come across this issue in which we need to get all the numeric occurrences. This type of problem generally occurs in competitive programming and also in web development. Let’s discuss certain ways in which this problem can be solved. Method #1 : Using List comprehension +
Output : The original string : There are 2 apples for 4 persons The numbers list is : [2, 4] Method #2 : Using
Output : The original string : There are 2 apples for 4 persons The numbers list is : [2, 4] You don’t need to be a math whiz to program well. The truth is, few programmers need to know more than basic algebra. Of course, how much math you need to know depends on the application you’re working on. In general, the level of math required to be a programmer is lower than you might expect. Although math and computer programming aren’t as correlated as some people might believe, numbers are an integral part of any programming language, and Python is no exception. In this tutorial, you’ll learn how to:
Let’s get started! Integers and Floating-Point NumbersPython has three built-in numeric data types: integers, floating-point numbers, and complex numbers. In this section, you’ll learn about integers and floating-point numbers, which are the two most commonly used number types. You’ll learn about complex numbers in a later section. IntegersAn integer is a whole number with no decimal places. For example, >>>
You can create an integer by typing the desired number. For instance, the following assigns the integer When you create an integer like this, the value You may already be familiar with how to
convert a string containing an integer to a number using
When you write large numbers by hand, you typically group digits into groups of three separated by a comma or a decimal point. The number 1,000,000 is a lot easier to read than 1000000. In Python, you can’t use commas to group digits in integer literals, but you can use underscores ( >>>
There’s no limit to how large an integer can be, which might be surprising considering that computers have a finite amount of memory. Try typing the largest number you can think of into IDLE’s interactive window. Python can handle it with no problem! Floating-Point NumbersA floating-point number, or float for short, is a number with a decimal place. >>>
Like integers, floats can be created from floating-point literals or by converting a string to a float with >>>
There are three ways to represent a floating-point literal. Each of the following creates a floating-point literal with a value of one million: >>>
The first two ways are similar to the two techniques for creating integer literals. The third approach uses E notation to create a float literal. To write a float literal in E notation, type a number followed by the letter Python also uses E notation to display large floating-point numbers: >>>
The float The literal Unlike integers, floats do have a maximum size. The maximum floating-point number depends on your system, but something like When you reach the maximum floating-point number, Python returns a special float value,
>>>
Python also uses You probably
won’t come across Check Your Understanding Expand the block below to check your understanding: Write a program that creates two variables, You can expand the block below to see a solution: First, assign the value Next, on a new line, assign the value Print both variables on separate lines by passing each variable to separate calls of
In the output, you can see that both numbers are the same: Although both variables are assigned the value When you’re ready, you can move on to the next section. Arithmetic Operators and ExpressionsIn this section, you’ll learn how to do basic arithmetic, such as addition, subtraction, multiplication, and division, with numbers in Python. Along the way, you’ll learn some conventions for writing mathematical expressions in code. AdditionAddition is performed with the The two numbers on either side of the You can add an Notice that the result of SubtractionTo subtract two numbers, just put a >>>
Just like adding two integers,
subtracting two integers always results in an The You can subtract a negative number from another number, but as you can see below, this can sometimes look confusing: >>>
Of the four examples above, the first is the most PEP 8 compliant. That said, you
can surround Using parentheses is a good idea because it makes your code more explicit. Computers execute code, but humans read code. Anything you can do to make your code easier to read and understand is a good thing. MultiplicationTo
multiply two numbers, use the >>>
The type of number you get from multiplication follows the same rules as addition and subtraction. Multiplying two integers results in an DivisionThe >>>
Unlike addition, subtraction, and multiplication, division with the Keep
in mind that
Integer DivisionIf writing >>>
The For example, The above example also illustrates that Let’s see what happens when you try to divide a number by >>>
Python gives you a ExponentsYou can raise a number to a power using the >>>
Exponents don’t have to be integers. They can also be floats: >>>
Raising a number to the power of For positive operands, the You can also raise numbers to negative powers: >>>
Raising a number to a negative power is the same as dividing The Modulus OperatorThe >>>
One of the most common uses of >>>
This makes sense because Things get a little tricky when you use the >>>
Although potentially shocking at first glance, these results are the product of a well-defined behavior in Python. To calculate the
remainder For example, to find Arithmetic ExpressionsYou can combine operators to form complex expressions. An expression is a combination of numbers, operators, and parentheses that Python can compute, or evaluate, to return a value. Here are some examples of arithmetic expressions: >>>
The rules for evaluating expressions are the same as in everyday arithmetic. In school, you probably learned these rules under the name order of operations. The You may notice that the expressions in the previous example do not follow the rule for putting a space on either side of all of the operators. PEP 8 says the following about whitespace in complex expressions:
Another good practice is to use parentheses to indicate the order in which operations should be performed, even if the parentheses aren’t necessary. For instance, Make Python Lie to YouWhat do you think >>>
Well, that’s . . . almost right. What in the heck is going on here? Is this a bug in Python? No, it’s not a bug! It’s a floating-point representation error, and it has nothing to do with Python. It’s related to the way floating-point numbers are stored in a computer’s memory. The number When represented in binary, something familiar yet possibly unexpected happens to the decimal number The binary representation of
Computers have finite memory, so the number
You may have noticed, however, that when asked to print Python doesn’t just chop off the digits in the binary representation for Because the approximation of For example, both This explains why, in the first example of this section, If all this is starting to make your head spin, don’t worry! Unless you’re writing programs for finance or scientific computing, you don’t need to worry about the imprecision of floating-point arithmetic. Math Functions and Number MethodsPython has a few built-in functions that you can use to work with numbers. In this section, you’ll learn about three of the most common:
You’ll also learn about a method you can use with floating-point numbers to check whether they have an integer value. Round Numbers With round()You can use >>>
>>>
Python 3 rounds numbers according to a strategy called rounding ties to even. A tie is any number whose last digit is five. When you round ties to even, you first look at the digit one decimal place to the left of the last digit in the tie. If that digit is even, then you round down. If the digit is odd, then you round up. That’s why You can round a number to a given number of decimal places by passing a second argument to >>>
The
number The second argument of >>>
Sometimes >>>
Dealing with floating-point numbers can be frustrating, but this frustration isn’t specific to Python. All languages that implement the IEEE floating-point standard have the same issues, including C/C++, Java, and JavaScript. In most cases, though, the little errors encountered with floating-point numbers are negligible, and the results of Find the Absolute Value With abs()The
absolute value of a number n is just n if n is positive and -n if n is negative. For example, the absolute value of To get the absolute value of a number in Python, you use
>>>
Raise to a Power With pow()Earlier, you learned how to raise a number to a power using the
For example, the following uses Just like with So, what’s the difference between The Here’s an example in which First, Check if a Float Is IntegralYou may be familiar with string methods like Number methods aren’t used very often, but there is one that can be useful. Floating-point numbers have an >>>
One use for The For even more math fun, check out The Python math Module: Everything You Need to Know! Check Your Understanding Expand the block below to check your understanding: Write a program that asks the user to input a number and then displays that number rounded to two decimal places. When run, your program should look like this:
You can expand the block below to see a solution: To get input from a user, pass the prompt to
Notice the space at the end of the prompt string. This ensures there’s a space between the text entered by the user when they start typing and the colon in the prompt. The value returned by Keep in mind that the above code assumes that the string Now you can use
Remember, the first argument to Finally, you can print the ouput by inserting
When you’re ready, you can move on to the next section. Print Numbers in StyleDisplaying numbers to a user requires inserting numbers into a string. You can do this with f-strings by surrounding a variable assigned to a number with curly braces: >>>
Those curly braces support a simple formatting language that you can use to alter the appearance of the value in the final formatted string. For example, to format the value of >>>
The colon ( The When >>>
To round to one decimal place, replace >>>
When you format a number as fixed point, it’s always displayed with the precise number of decimal places that you specify: >>>
You can insert commas to group the integer part of large numbers by the thousands with the >>>
To
round to some number of decimal places and also group by thousands, put the >>>
The specifier >>>
Another useful option is The >>>
The formatting mini language is powerful and extensive. You’ve only seen the basics here. For more information, check out the official documentation. Check Your Understanding Expand the block below to check your understanding: Print the number You can expand the block below to see a solution: Let’s build up our f-string one step at a time. First, the f-string that displays the value >>>
This might look kind of odd, but it sets you up to add the formatting specifiers. To ensure that the value is displayed as
a floating-point number, put a colon ( >>>
By default, Python displays the number with six decimal places of precision. Currency should have only two decimal places of precision, so you can add >>>
To
display the number with digits grouped by commas, insert a comma ( >>>
Finally, add a dollar sign ( >>>
F-strings are just one way to format numbers for display. Check out A Guide to the Newer Python String Format Techniques for even more ways to format numbers and other text in Python. When you’re ready, you can move on to the next section. Complex NumbersPython is one of the few programming languages that provides built-in support for complex numbers. While complex numbers don’t often come up outside the domains of scientific computing and computer graphics, Python’s support for them is one of its strengths. If you’ve ever taken a precalculus or higher-level algebra math class, then you may remember that a complex number is a number with two distinct components: a real part and an imaginary part. To create a complex number in Python, you simply write the real part, then a plus sign, then the imaginary part with the letter j at the end: When you inspect the value of This convention helps eliminate any confusion that the displayed output may represent a string or a mathematical expression. Imaginary numbers come with two properties, >>>
Notice that Python returns both the real and imaginary components as floats, even though they were specified as integers. Complex numbers also have a >>>
For any complex number, its conjugate is the complex number with the same real part and
an imaginary part that is the same in absolute value but with the opposite sign. So in this case, the complex conjugate of Except for the floor division operator ( >>>
Interestingly, although not surprising from a mathematical point of view, >>>
For floats and integers, Now that you’ve seen the basics of complex numbers, you might be wondering when you would ever need to use them. If you’re learning Python for web development, data science, or general-purpose programming, the truth is that you may never need to use complex numbers. On the other hand, complex numbers are important in domains such as scientific computing and computer graphics. If you ever work in those domains, then you may find Python’s built-in support for complex numbers useful. Conclusion: Numbers in PythonIn this tutorial, you learned all about working with numbers in Python. You saw that there are two basic types of numbers—integers and floating-point numbers—and that Python also has built-in support for complex numbers. In this tutorial, you learned:
No matter your comfort level with numbers and math, you’re now ready to perform all kinds of calculations in your Python code. You can use this knowledge to solve a wide range of problems that you’ll encounter in your programming career. Further ReadingFor additional information on numbers and math in Python, check out these resources:
How to get some numbers from a list in Python?Another way to get some numbers as input and store it in a list is as follows. This method uses the list comprehension technique. list_of_numbers = [int(i) for i in input().split()] print(list_of_numbers) Output: 1 3 5 7 [1, 3, 5, 7] Thank you. Also read: String split and join in Python List and dictionary comprehension in python
How do you represent numbers in Python?In Python, we can represent these numbers by appropriately placing a prefix before that number. The following table lists these prefixes. When you run the program, the output will be: We can convert one type of number into another.
How many types of numbers are there in Python?Python Numbers. There are three numeric types in Python: int; float; complex; Variables of numeric types are created when you assign a value to them:
How to generate random numbers in Python?Python defines a set of functions that are used to generate or manipulate random numbers through the random module. Functions in the random module rely on a pseudo-random number generator function random() , which generates a random float number between 0.0 and 1.0.
How do you get only numbers in Python?How to extract integers from a string in Python. a_string = "0abc 1 def 23". numbers = []. for word in a_string. split():. if word. isdigit():. numbers. append(int(word)). print(numbers). How do you code numbers in Python?Variables of numeric types are created when you assign a value to them:. x = 1 # int. y = 2.8 # float. ... . print(type(x)) print(type(y)) ... . Integers: x = 1. ... . Floats: x = 1.10. ... . Floats: x = 35e3. ... . Complex: x = 3+5j. ... . Convert from one type to another: x = 1 # int. ... . Import the random module, and display a random number between 1 and 9:. How do you display numbers in Python?How to display numbers integer in python ? For example: number1 = raw_input('Write one number: ') number2 = raw_input('Write other number: ') result = number1 + number2 print "The sum of the numbers is: %d" % result # here, display the result of the operatio n.
How do you extract numbers from a list in Python?Summary: To extract numbers from a given string in Python you can use one of the following methods:. Use the regex module.. Use split() and append() functions on a list.. Use a List Comprehension with isdigit() and split() functions.. Use the num_from_string module.. |