Creation and use of strings in Python
“Strings are amongst the most popular types in Python. We can create them simply by enclosing characters in quotes. Python treats single quotes the same as double quotes.” Link info: http://www.tutorialspoint.com/python/python_strings.htm
“The string module contains a number of useful constants and classes, as well as some deprecated legacy functions that are also available as methods on strings. In addition, Python’s built-in string classes support the sequence type methods described in the Sequence Types — str, unicode, list, tuple, bytearray, buffer, xrange section, and also the string-specific methods described in the String Methods section. To output formatted strings use template strings or the % operator described in the String Formatting Operations section. Also, see the re module for string functions based on regular expressions.
The constants defined in this module are:
string.ascii_letters
The concatenation of the ascii_lowercase and ascii_uppercase constants described below. This value is not locale-dependent.
string.ascii_lowercase
The lowercase letters ‘abcdefghijklmnopqrstuvwxyz’. This value is not locale-dependent and will not change.
string.ascii_uppercase
The uppercase letters ‘ABCDEFGHIJKLMNOPQRSTUVWXYZ’. This value is not locale-dependent and will not change.
string.digits
The string ‘0123456789’.
string.hexdigits
The string ‘0123456789abcdefABCDEF’.
string.letters
The concatenation of the strings lowercase and uppercase described below. The specific value is locale-dependent, and will be updated when locale.setlocale() is called.
string.lowercase
A string containing all the characters that are considered lowercase letters. On most systems this is the string ‘abcdefghijklmnopqrstuvwxyz’. The specific value is locale-dependent, and will be updated when locale.setlocale() is called.
string.octdigits
The string ‘01234567’.
string.punctuation
String of ASCII characters which are considered punctuation characters in the C locale.
string.printable
String of characters which are considered printable. This is a combination of digits, letters, punctuation, and whitespace.
string.uppercase
A string containing all the characters that are considered uppercase letters. On most systems this is the string ‘ABCDEFGHIJKLMNOPQRSTUVWXYZ’. The specific value is locale-dependent, and will be updated when locale.setlocale() is called.
string.whitespace
A string containing all characters that are considered whitespace. On most systems this includes the characters space, tab, linefeed, return, formfeed, and vertical tab.”
Link info: https://docs.python.org/2/library/string.html
Creation and use of dictionaries in Python:
Dictionaries are the fundamental data structure in Python, and a key tool in any Python programmer’s arsenal. They allow O(1) lookup speed, and have been heavily optimized for memory overhead and lookup speed efficiency. Link info: https://developmentality.wordpress.com/2012/03/30/three-ways-of-creating-dictionaries-in-python/
Each key is separated from its value by a colon (:), the items are separated by commas, and the whole thing is enclosed in curly braces. An empty dictionary without any items is written with just two curly braces, like this: {}.
Keys are unique within a dictionary while values may not be. The values of a dictionary can be of any type, but the keys must be of an immutable data type such as strings, numbers, or tuples.
Accessing Values in Dictionary:
To access dictionary elements, you can use the familiar square brackets along with the key to obtain its value.
dict = {‘Name’: ‘Zara’, ‘Age’: 7, ‘Class’: ‘First’};
print “dict[‘Name’]: “, dict[‘Name’]
print “dict[‘Age’]: “, dict[‘Age’]
Link info: http://www.tutorialspoint.com/python/python_dictionary.htm
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