1.8 Strings and Data Structures

x = 'Hello'    # x is a string

# Build strings for later use

mystr = 'abcbdefghija'

mynum = '1234'

mytitle = 'This Is My Title'

dot = '.'

letters = ('A', 'B', 'C')

mess = '     asdasdas dd       '

intab = "aeiou"

outtab = "12345"

str = "this is string example....wow!!!"

messy = 'Change The Case'

commaland = 'a,b,c,d,e,f'

print(mystr.capitalize())       # Capitalize first character

print(mystr.center(20, '$'))    # Centre text. Pad with provided text

print(mystr.count('a'))         # Count occurrences of a substring

print(mystr.endswith('ija'))    # Check suffix (ending), return Boolean

print(mystr.find('b'))          # Find and return first occurrence of substring, if substring not found return -1

'12' in '1234'                  # Use instead of find() to verify the substring

print(mynum.isalnum())          # Return true if all characters in the string are alphanumeric and there is at least one character, false otherwise.

print(mystr.isalpha())          # Return true if all characters in the string are alphabetic and there is at least one character, false otherwise.

print(mynum.isdigit())          # Return true if all characters in the string are digits and there is at least one character, false otherwise.

print(mytitle.istitle())        # Return true if the string is a titlecased string and there is at least one character, false otherwise.

print(mytitle.isupper())        # Return true if all cased characters in the string are uppercase and there is at least one cased character,

                                # false otherwise.

print(dot.join(letters))        # Return a string, which is the concatenation of the strings in the sequence.

print(mytitle.lower())          # Return a copy of the string with all the cased characters converted to lowercase.

print(mess.lstrip())            # Return a copy of the string with leading characters removed.

                                # The chars argument is a string specifying the set of characters to be removed.

                                # If omitted or None, the chars argument defaults to removing whitespace.

                                # The chars argument is not a prefix; rather, all combinations of its values are stripped

                                # maketrans() links the translation table (links), translate() applies the table

print(str.translate(str.maketrans(intab, outtab))) 

print(mystr.replace('a','Q'))   # Return a copy of the string with the substrings replaced

print(mystr.rfind('b'))         # Find and return last occurrence of substring, if substring not found return -1

print(mess.rstrip())            # Return a copy of the string with trailing characters removed.

                                # The chars argument is a string specifying the set of characters to be removed.

                                # If omitted or None, the chars argument defaults to removing whitespace.

                                # The chars argument is not a prefix; rather, all combinations of its values are stripped

print(commaland.split(','))     # Return a list of the words in the string. With or without delimiter string

print(mystr.startswith('abc'))  # Check prefix (beginning), return Boolean

print(mystr.strip('ab'))        # Return a copy of the string with the leading and trailing characters removed

print(messy.swapcase())         # Return a copy of the string with uppercase characters converted to lowercase and vice versa.

print(str.title())              # Return a titlecased version of the string where words start with an uppercase character 

                                # and the remaining characters are lowercase.

print(str.upper())              # Return a copy of the string with all the cased characters converted to uppercase.

# FUN STRING STUFF NOT DIRECTLY PART OF THE STRING LIBRARY

print(len(mystr))               # len() returns the length of an object.  Strings in Python are objects. Not a String

                                # library function.  Standard Python Library.

print('*' * 10)                 # use the multiply operator for printing repeated characters

print (messy + mystr)           # use the concatenation operator for joining two strings

print(":".join(mystr))          # provide join() a sequence and separate it with the string

                                # calling join. In this case 

                                # a ':' string called join()

word = 'sesquipedalian'

i = 0

print(word[i])      # subscript (indexing) of the string

print(word[1])      # positive moves to the right

print(word[-1])     # negative moves to the left, supercool

print(word[i:10])   # slice

print(word[0:2])    # slice characters from position 0 (included) to 2 (excluded)

print(word[2:5])    # slice characters from position 2 (included) to 5 (excluded)

print(word[:2])     # slice character from the beginning to position 2 (excluded)

print(word[4:])     # slice characters from position 4 (included) to the end

print(word[-2:])    # characters from the second-last (included) to the end

 +---+---+---+---+---+---+

 | P | y | t | h | o | n |

 +---+---+---+---+---+---+

 0   1   2   3   4   5   6

-6  -5  -4  -3  -2  -1

caf_specials = [ 'breakfast sandwich', 'milk', 'rice', 'pizza', 'salad', 'fish and chips' ]

list1 = ['dogs', 'cats', 2, 1]    # a mixed list of strings and numbers

list2 = [1, 2, 3, 4, 5 ]          # a list of numbers

list3 = ['a', 'b', 'c', 'd']      # a list of strings

list1 = ['dogs', 'cats', 2, 1]    # a mixed list of strings and numbers

list2 = [1, 2, 3, 4, 5 ]          # a list of numbers

list3 = ['a', 'b', 'c', 'd']      # a list of strings

print(list1[0])         # read from the list using a hard-coded value

i = 2

print(list1[i])         # read from the list use a variable

list1[3] = 'hamster'    # write to the list using a hard-coded value

list1[i] = 'bird'       # write to the list using a variable

print(list1)            # this gives us proof of output, but it might not be in a user friendly format.

                        # it still looks like a list.

list3 = ['a', 'b', 'c', 'd']

list2 = [1, 2, 3, 4, 5 ]

list3 = list3 * 2        # repetition

print(list3)

list3 = list3 + list2    # concatenation

print(list3)

print(list3[0:5])        # slicing

print(list2[-1])        # indexing, specifically: negative number indexing

list3 = ['a', 'b', 'c', 'd']

list2 = [1, 2, 3, 4, 5 ]

del(list3[0])       # Remove an item or a slice from a list

print(list3)

print(len(list2))   # length of list

print('b' in list3) # check for membership

for i in list3:     # use for loop counter to access elements

    print(i)

list3 = ['a', 'b', 'c', 'd']

list2 = [1, 2, 3, 4, 5 ]

list4 = ['z', '2', 'g', '1', 'a']

list3.append('qq') # add an item to the end of the list

print(list3)

list3.extend(['ww','tt']) # add a series of elements to the list

print(list3)

list3.insert(4, 'yyyyy')    # Insert an item at a given position.

print(list3)                # The first argument is the index of the

                            # element before which to insert

list3.remove('ww')  # Remove the first item from the list that matched

print(list3)

list3.pop(0) # Remove the item at the given position in the list, and return it.

print(list3)    # If no index is specified, a.pop() removes and returns the last item in the list.

list2.clear()   # Equivalent to del

print(list3)

print(list3.index('qq'))    # Return the index of the first item provided

print(list3.count('qq'))    # Return the number of times item appears

list4.sort()                # Sort the items of the list. Items must be of like type

print(list4)

list4.reverse()             # Reverse the elements of the list

print(list4)

list2 = list4.copy()        # shallow copy of list ... yes, there's a deepcopy() too

print(list2)

# This looks like a copy, and it works, but not the way you might think

foo = [1,2,3]

boo = foo

boo.pop()

print(boo)

print(foo)

#If you manipulate either foo or boo, they'll both change because they are referencing the same (one, singular, 1) list

#use copy() to make a shallow copy of your list

original = [1,2,3]

clone = original.copy()

clone.pop()

print(clone)

print(original)

myList = [22, 4, 99]    #build a list, elements can change

myTuple = (22, 4, 99)   #build a tuple, elements CANNOT change

#I want to get input, and hold it in a list.

myList[0] = input('Change the value in the first element of the list: ')

print(myList) #see, it changed

#YOU CANNOT CHANGE A TUPLE: myTuple[0]=input('change a value: ') #CRASH!!

myNewTuple = tuple(myList)  #CAST myList INTO a TUPLE

print(myNewTuple)           #print the Tuple

someList = list(myNewTuple) #CAST myNewTuple INTO a LIST

print(someList)             #print the LIST

contacts = {'bob':6471234567, 'sally':6477778888} #build a dictionary

#you can also build dictionaries using the dict() constructor. Check out the API for details

print(contacts) #print the dictionary, notice the unfriendly output

#use a for loop to make the output more readable

for name,tel in contacts.items():   #use the item() to access the key and value

    print(name, tel)

contacts['jojo'] = 6475556666   #add a key and value to the dictionary

print(contacts)

aListofKeysOnly = list(contacts.keys()) #Just the keys, put in a list

print(aListofKeysOnly)

aListofValuesOnly = list(contacts.values()) #Just the values, put in a list

print(aListofValuesOnly)

del contacts['bob'] #where did bob go?

print(contacts)