# Python Introduction: Types¶

Let's evaluate some simple expressions.

In [1]:

    3*2

Out[1]:

    6

In [2]:

    5+3*2

Out[2]:

    11

You can use `type()` to find the type of an expression.

In [3]:

    type(5+3*2)

Out[3]:

    int

Now add decimal points.

In [4]:

    5+3.5*2

Out[4]:

    12.0

In [5]:

    type(5+3.0*2)

Out[5]:

    float

Strings are written with single (`'`) or double quotes (`"`)

In [6]:

    "hello"

Out[6]:

    'hello'

Multiplication and addition work on strings, too.

In [2]:

    3 * 'hello ' + "sc15"

Out[2]:

    'hello hello hello sc15'

Lists are written in brackets (`[]`) with commas (`,`).

In [8]:

    [5, 3, 7]

Out[8]:

    [5, 3, 7]

List entries don't have to have the same type.

In [9]:

    ["hi there", 15, [1,2,3]]

Out[9]:

    ['hi there', 15, [1, 2, 3]]

"Multiplication" and "addition" work on lists, too.

In [10]:

    [1,2,3] * 4 + [5, 5, 5]

Out[10]:

    [1, 2, 3, 1, 2, 3, 1, 2, 3, 1, 2, 3, 5, 5, 5]

Hmmmmmm. Was that what you expected?

In [1]:

    import numpy as np

    np.array([1,2,3]) * 4 + np.array([5,5,5])

Out[1]:

    array([ 9, 13, 17])

In [ ]: