Introduction to Python | Tutorial 2

Numbers

Jyotirmay Zamre, Sammarth Kumar

There are three numeric types in Python:

int - integer
float - floating point number
complex - complex number

Integer

Integers are positive and negative whole numbers, just like those you would see in math. They can be assigned to a variable easily. For example, we have

x = 5

Here, we have a variable with an identifier as x and an integer value of 5. Therefore the object is of int type.

Boolean

Under integers, we have a subdivision of Boolean values. Boolean values are True and False, which have their respective integer counterparts as 1 and 0. Boolean values can be used to evaluate any expression in Python through comparison. Conditional statements in Python also return boolean values and other actions can be taken on the basis of the returned value.


    print(10 > 9)
    print(10 < 9)
                      
      True
      False

Float

Floats are floating point numbers. They are positive and negative decimal values. Now, while floats are very accurate, after a certain decimal place, they are not. In the Python Docs this problem is stated as follows.

Unfortunately, most decimal fractions cannot be represented exactly as binary fractions. A consequence is that, in general, the decimal floating-point numbers you enter are only approximated by the binary floating-point numbers actually stored in the machine.

If you are not familiar with binary numbers, a binary number system consists of only 0s and 1s. If you want to see how you can convert binary numbers to decimal numbers you can check this link out.

To assign a float value to a variable, you would do the same thing as that for an integer. You can also use scientific notation:


                y = 9.34e4

If you run print(y), the output should be 93400.0. Even if there are no decimal places, a float will always have a decimal point.

Complex

Complex numbers are written with 'j' as an imaginary part. If you don't already know what complex numbers are, they consist of a real number component and imaginary number component. In mathematics, j would be replaced by i which is also known as iota and is the square root of negative one.

In Python, you simply use a j instead of an i. For example the complex number 3 + 4i would be written as 3 + 4j in Python.

To get the real part of a complex number, we use the real method (a method performs an operation on an object). We can use imag to get the imaginary part as well.


    import math
    y = 3 + 4j
    print(y.real,y.imag)
                      
      3.0 4.0

These return float values of each component. Here you see that we have used the statement import math. This is used to import the code inside the math module file here. Essentially, it allows us to use functions created there. You will learn more about all this in our functions tutorial. For now think of it as us borrowing an operation from another file.

Conversions between Numbers

Python provides built-in functions to convert between number values. The three functions are int(),float and complex. Let's see how they can be used.


    a = 3
    b = 4.0
    c = 2 + 5j
    print(int(b),int(c))
    print(float(a),float(c))
    print(complex(a),complex(b))
                      
      4
      3.0
      (3+0j) (4+0j)

You can convert int and float to complex, but the vice-versa will not work and will produce an error.

That's it for this tutorial! Click Next to access the next tutorial!

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