=================================
Module: Formating not calculating
=================================

.. _formating:

.. index:: format strings

.. |a| image:: /images/all/python-basics/modulo1-100.png

Objectives
==========
   
.. tabularcolumns:: | c | l |
   :border: none

+-------+-------------------------------------------------------------------------+
|  |a|  | If all calculations are finished, print is often used to present all    |
|       | values as a string. Beside the old %s-Operator in Python 3.x a new      |
|       | function is available. Examples are showing some nice solutions.        | 
+-------+-------------------------------------------------------------------------+


Instructions
============
:Tasks:

1. Change the examples presented in the old as in the new notation.
2. Print a list, as it is listed on a sales slip.
3. Look at the examples in the Python documentation at:
    http://docs.python.org/2/library/string.html#format-examples

String formating with the Moduluo-Operator %
============================================

Principles to the old version
=============================

- The % sign is a wildcard, followed by a letter indicating the data type.
- Examples: %s, %d, %f, %2d, %2.3f
- The number after the percent sign specifies the precision to be used for output.
- The last % sign initiates the handover of parmaeter(s) to be used for the placeholder.
- The number of parameters (list, tuple) must match the number of placeholders.

Special case: Dictionary as parameter
=====================================

- If the parameter is a dictionary, then the wildcard must matching the names (keys)
  of the dictinary.

Example 1
=========
::

  for i in range(1,11):
    print("%s * %s = %s" % (i,10,i*10))


Example 2
==========

.. ifconfig:: language=='de'

  ::

    print("%ser's Fritz, f%st fr%se %se" % ("Fisch","isch","isch","Fisch"))


.. ifconfig:: language=='en'

  ::

    print("The %s f%sx j%ss" % ("brown","o","ump"))


Example 3
=========
:: 
  
  # create a dictionary...
 
  mushrooms = {} # empty dictionary
  mushrooms['cep'] = ['eatable x times', "mixed forest", "Boletus edulis"]
  mushrooms['fly amanita'] = ["eatable once", "coniferous forest", "Amanita muscaria"]
  mushrooms['bay bolete'] = ["eatable x times", "mixed forest", "Boletus badius"]
  mushrooms['Coprinus'] = ['eatable x times', "meadow", "Coprinus"]

  # print the content:

  print('''Pretty print dictionary of mushrooms:\n ''')

  for i in mushrooms.keys():
      print("""kind = %s, eatable = %s, be found = %s; """.format(i, 
                                                                  mushrooms[i][0],
                                                                  mushrooms[i][1]))


Example 4
==========

::

  adress = {"firstnamename": "Robin",
            "lastname": "Hood",
            "location": "Sharewood Forest",
            "mark": "Bow & Arrow"}

  print("""
           Wanted %(lastname)s, %(firstname)s 
           special mark %(mark)s
           lives in %(location)s
	""" % (adress)


==============================
String formating with format()
==============================
This new method was discussed in  `PEP 3101 <http://www.python.org/dev/peps/pep-3101/>`_
and is available since Python version 2.7.

Principles to the new version
=============================

- placehoder is a pair of curly braces
- the parameter are placed in the *format* method

The following examples repeat the old examples above and should the
cause the same result.

Example 1
=========
::

  for i in range(1,11):
    print('{} * {} = {}'.format(i,10,i*10))

The same example, but more table like:
::

  for i in range(1,11):
    print('{:2d} * {:2d} = {:3d}'.format(i,10,i*10))


::
  
  x = 10
  print('{0:2d} {1:3d} {2:4d}'.format(x, x*x, x*x*x))


.. ifconfig:: language=='de'

  ::

    print('{}ser's Fritz, f{}t fr{}e {}e".format("Fisch","isch","isch","Fisch"))


.. ifconfig:: language=='en'

  ::

    print("The {} f{}x j{}s".format("brown","o","ump"))

Example 3
=========
:: 
  
  # create a dictionary...
 
  mushrooms = {} # empty dictionary
  mushrooms['cep'] = ['eatable x times', "mixed forest", "Boletus edulis"]
  mushrooms['fly amanita'] = ["eatable once", "coniferous forest", "Amanita muscaria"]
  mushrooms['bay bolete'] = ["eatable x times", "mixed forest", "Boletus badius"]
  mushrooms['Coprinus'] = ['eatable x times', "meadow", "Coprinus"]

  # print the content:

  print('''Pretty print dictionary of mushrooms:\n ''')

  for i in mushrooms.keys():
      print("""kind = {}, eatable = {}, be found = {}; """.format(i, 
                                                                  mushrooms[i][0],
                                                                  mushrooms[i][1]))

Excample 4
==========
::

  adress = {"firstnamename": "Robin",
            "lastname": "Hood",
            "location": "Sharewood Forest",
            "mark": "Bow & Arrow"}
  print("""
           Wanted {lastname}, {firstname} 
           special mark {mark}
           lives in {location}
	""" % (**adress)

Example 5
==========
A little collection fo exotic versions...
::

  >>> name ="Peter"
  >>> "{!r:>10}".format(name)
  "   'Peter'"

  >>> '{:x>42}'.format(name)
  'xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxPeter'