Getting Started
===============

There are many different ways to use Python. For now we will use an
iPython notebook.

Create a directory of your choice (where you want to locate your python
files). Open a command shell in this directory and start the iPython
notebook server by typing \`ipython notebook'. This should open your web
browser or at least show you the URL that can be opened by the web
browser of your choice. Usually http://localhost:8888

In your browser window you can now open or create notebook files
(.ipynb) in your directory. Once you opened a notebook you can type 'h'
to get help on some useful shortcuts. This text is a static version of
such a notebook. You can download it (see start page of this
documentation) or type it on your own.

Using Python as a Calculator
----------------------------

.. code:: python

    2+2




.. parsed-literal::

    4



.. code:: python

    50-5*6




.. parsed-literal::

    20



.. code:: python

    (50-5*6) / 4




.. parsed-literal::

    5.0



.. code:: python

    8/5




.. parsed-literal::

    1.6



.. code:: python

    8//5




.. parsed-literal::

    1



.. code:: python

    8%5




.. parsed-literal::

    3




Variables and Types
-------------------

Naming
~~~~~~

Do not use reserved names:

and, as, assert, break, class, continue, def, del, elif, else, except,
exec, finally, for, from, global, if, import, in, is, lambda, not, or,
pass, print, raise, return, try, while, with, yield

Use a-z, A-Z, 0-9, \_

Start with a letter

.. code:: python

    myvar = 12

.. code:: python

    myvar




.. parsed-literal::

    12



.. code:: python

    myvar + 10




.. parsed-literal::

    22




.. code:: python

    myvar = myvar + 10

.. code:: python

    myvar




.. parsed-literal::

    22



.. code:: python

    type(myvar)




.. parsed-literal::

    int



.. code:: python

    myvar = 22.0

.. code:: python

    type(myvar)




.. parsed-literal::

    float



.. code:: python

    mybool = True

.. code:: python

    type( mybool)




.. parsed-literal::

    bool



.. code:: python

    x = 1.0 + 1.0j

.. code:: python

    type( x)




.. parsed-literal::

    complex



.. code:: python

    x.real




.. parsed-literal::

    1.0



.. code:: python

    myvar**0.5




.. parsed-literal::

    4.69041575982343



type casting
~~~~~~~~~~~~

.. code:: python

    type(myvar)




.. parsed-literal::

    float



.. code:: python

    myvar=22.9

.. code:: python

    int(myvar)




.. parsed-literal::

    22



Comparision
~~~~~~~~~~~

.. code:: python

    1 > 0




.. parsed-literal::

    True



.. code:: python

    type(0 > 1)




.. parsed-literal::

    bool



.. code:: python

    2 >= 2




.. parsed-literal::

    True



.. code:: python

    not myvar != 1




.. parsed-literal::

    False



.. code:: python

    (1==1) | (1==2)




.. parsed-literal::

    True




Composite types: Strings, List, Tuple, Set and Dictionaries
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Strings
^^^^^^^

.. code:: python

    s = "Hello Everybody"

.. code:: python

    type(s)




.. parsed-literal::

    str



.. code:: python

    s




.. parsed-literal::

    'Hello Everybody'



.. code:: python

    len(s)




.. parsed-literal::

    15



.. code:: python

    s.replace('Hello', 'Goodbye')




.. parsed-literal::

    'Goodbye Everybody'



.. code:: python

    s[0]




.. parsed-literal::

    'H'



.. code:: python

    s[6:]




.. parsed-literal::

    'Everybody'



.. code:: python

    s[0:1]




.. parsed-literal::

    'H'



.. code:: python

    s[:-3]




.. parsed-literal::

    'Hello Everyb'



.. code:: python

    s[0:10:2]




.. parsed-literal::

    'HloEe'



.. code:: python

    s[::-2]




.. parsed-literal::

    'yoyeEolH'



.. code:: python

    s2 = ' and Nobody'

.. code:: python

    s + s2




.. parsed-literal::

    'Hello Everybody and Nobody'



.. code:: python

    s[0:5] + s2[-7:]




.. parsed-literal::

    'Hello Nobody'



.. code:: python

    print( "The number {} is great".format(myvar))


.. parsed-literal::

    The number 22.9 is great


Lists
^^^^^

.. code:: python

    l = [1,2,3,4]

.. code:: python

    l




.. parsed-literal::

    [1, 2, 3, 4]



.. code:: python

    type(l)




.. parsed-literal::

    list



.. code:: python

    l2 = list(range(10))

.. code:: python

    l2




.. parsed-literal::

    [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]



.. code:: python

    l5 = list(range(-10,11,2))

.. code:: python

    l5




.. parsed-literal::

    [-10, -8, -6, -4, -2, 0, 2, 4, 6, 8, 10]



.. code:: python

    l3 = [1.1, 2, 'Hallo', 1+1j]

.. code:: python

    l3




.. parsed-literal::

    [1.1, 2, 'Hallo', (1+1j)]



.. code:: python

    l3[1]




.. parsed-literal::

    2



.. code:: python

    l4 = [1,2,3,[1,2,3,[5,6,7]]]

.. code:: python

    l4




.. parsed-literal::

    [1, 2, 3, [1, 2, 3, [5, 6, 7]]]



.. code:: python

    l4[3][3]




.. parsed-literal::

    [5, 6, 7]



.. code:: python

    l4[3][3][2]




.. parsed-literal::

    7



.. code:: python

    ls = list(s)

.. code:: python

    ls




.. parsed-literal::

    ['H', 'e', 'l', 'l', 'o', ' ', 'E', 'v', 'e', 'r', 'y', 'b', 'o', 'd', 'y']



.. code:: python

    ls.sort()

.. code:: python

    ls




.. parsed-literal::

    [' ', 'E', 'H', 'b', 'd', 'e', 'e', 'l', 'l', 'o', 'o', 'r', 'v', 'y', 'y']



.. code:: python

    ls.append( 'X')

.. code:: python

    l6 = []

.. code:: python

    l6




.. parsed-literal::

    []



.. code:: python

    l6.append( 'H')

.. code:: python

    l6.append('a')

.. code:: python

    l6




.. parsed-literal::

    ['H', 'a']



.. code:: python

    l6.insert( 0, 'X')

.. code:: python

    l6




.. parsed-literal::

    ['X', 'H', 'a']



.. code:: python

    l6.insert( 2, 'A')

.. code:: python

    l6




.. parsed-literal::

    ['X', 'H', 'A', 'a']



.. code:: python

    l6[0] = 'x'

.. code:: python

    l6




.. parsed-literal::

    ['x', 'H', 'A', 'a']



Tuple
^^^^^

similiar to list but it is impossible to modify

.. code:: python

    t1 = (1,2,3,4)

.. code:: python

    t1




.. parsed-literal::

    (1, 2, 3, 4)



.. code:: python

    # t1[0] = 3

Dictionaries
^^^^^^^^^^^^

.. code:: python

    d1 = {'par1': 5, 'par2': 10}

.. code:: python

    d1




.. parsed-literal::

    {'par1': 5, 'par2': 10}



.. code:: python

    type(d1)




.. parsed-literal::

    dict



.. code:: python

    d1['par1']




.. parsed-literal::

    5



.. code:: python

    d1['par1']=1

.. code:: python

    d1['par3']=22

.. code:: python

    d1




.. parsed-literal::

    {'par1': 1, 'par2': 10, 'par3': 22}



Set
^^^

.. code:: python

    basket = {'apple', 'orange', 'apple', 'pear', 'orange', 'banana'}

.. code:: python

    print(basket)


.. parsed-literal::

    {'banana', 'apple', 'pear', 'orange'}


.. code:: python

    'orange' in basket




.. parsed-literal::

    True



.. code:: python

    'lemon' in basket




.. parsed-literal::

    False



.. code:: python

    a = set('abracadabra')
    b = set('alacazam')

.. code:: python

    a, b




.. parsed-literal::

    ({'a', 'b', 'c', 'd', 'r'}, {'a', 'c', 'l', 'm', 'z'})



.. code:: python

    a-b




.. parsed-literal::

    {'b', 'd', 'r'}



.. code:: python

    a & b




.. parsed-literal::

    {'a', 'c'}



.. code:: python

    a | b




.. parsed-literal::

    {'a', 'b', 'c', 'd', 'l', 'm', 'r', 'z'}