Programming in python - Week 3

Programming in python - Week 3

• 1.
  Programming in Python Week-3Content
• 2.
  Data types
• 3.
  Strings in Python ●Strings can be surrounded by single or double quotations. ● Can be multiline with 3 double/single quotation marks. ● Are stored in the memory as arrays ● Python doesn’t have character data type, the characters are also internally stored as strings of length 1. ● You can access any characters of the string using indices. ● str_name[index] will give you the character at that index in the string. ● str_name[start_index: end_index] will give substring ● Strings are immutable
• 5.
  Strings & Accessingcharacters
• 6.
  alpha = ‘c’c alpha 0 alpha = ‘coffee’ c alpha 0 o f f e e 1 2 3 4 5 index alpha[4] e 4 f f e 2 3 4 alpha[2:5]
• 7.
  P Y TH O N C L A S S E S str1 = str2 = 0 1 2 3 4 5 0 1 2 3 4 5 6 + = P Y T H O N 0 1 2 3 4 5 C L A S S E S 6 7 8 9 10 11 12 add = N 5 str1[5] S 9 add[9]
• 8.
  P Y TH O Nstr1 = 0 1 2 3 4 5 * 3 multiply = P Y T H O N 0 1 2 3 4 5 Y T H O N 6 7 8 9 10 11 P Y T H O N 12 13 14 15 16 17 P
• 9.
  Now: print(“Addition of %sand %s is %s”, %(str1, str2, add)) Initially: print(“Addition of ” + str1 + “ and “ + str2 + “ is: “ + add ) Now: can be done for integers too print(“Addition of %i and %i is %i”, %(num1, num2, add))
• 10.
  Python Lists ● Storemultiple values in a single variable ● A single list may contain items of any data type ● len() can be used to get the length of the list ● append() can be used to add an element to an existing list ● remove() can be used to remove the first occurence of the specified item in the list ● Each element of the list has a definite position - index starting from 0 ● Lists are mutable
• 11.
  List Slicing 1 23 1 1 1 0 1 2 3 4 5 -6 -5 -4 -3 -2 -1 3 1 1 1 2 3 4 5 -4 -3 -2 -1 list[2:6] 3 1 1 2 3 4 -4 -3 -2 list[-4:-1] 3 1 1 1 2 3 4 5 -4 -3 -2 -1 list[2:] 1 2 0 1 -6 -5 list[:-4]
• 12.
  Tuples ● Identical tolists but created using () ● Tuples are immutable ● Indexing and slicing works similar to strings and lists ● Use tuples instead of list when you don’t want data to be modified ● When the amount of data is too huge, tuples work faster than lists
• 13.
  Operator Precedence andAssociativity in Python ● Combination of values, variables, operators and function calls makes a valid expression. ● When there are more than 1 operators in an expression, rules of precedence are used. ● If more than 1 operator is in the same group and hence has same precedence, associativity is used to evaluate the expression. ● ** has right-to-left associativity, rest all operators have left-to-right associativity
• 18.
  Homework Questions