GGC

14. Appendix 2: Python Syntax Examples

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70
# the '#' character makes a COMMENT separating Python from English x = 3 # create the VARIABLE with NAME x and STORE INT VALUE 3 Sebastien_Score = 9001 # variable names can be long, but no spaces! y = 1.0 * 3 # y stores EXPRESSION's RETURN FLOAT value 3.0 z = "Hi There!" # z stores a STRING value w = False # w stores a BOOLEAN value v = [3, 30, "Hello World"] # v stores a LIST of values print(z) # print function displays output ("Hi There!") # Maths a = 3 b = 3.0 # b stores 3.0 (float values are decimal approximations) c = 7 // 2 # c stores 3 (int division always gives ints) d = 7 % 2 # d stores 1 (Mod or Remainder of the division) a = 5 # change the value of a to 5 a += 1 # INCREMENT the value of a by 1 (to 6) # Boolean Operators a = (3 > 2) # a stores True because 3 is greater than 2 a = (2 >= 2) # a stores True because 2 is greater than or equal to 2 a = (3 < 2) # a stores False because 3 is not less than 2 a = (2 <= 2) # a stores True because 2 is less than or equal to 2 a = (3 != 2) # a stores True because 3 is not equal to 2 a = (3 == 3) # a stores True because 3 is equal to 3 a = (True and False) # a stores False, AND returns True only when both sides are True a = (True or False) # a stores True, OR returns True if at least 1 side is True a = (not False) # a stores True, NOT returns opposite # BLOCKS are sections of any code chunked together with INDENTATION # BLOCKS start with a ':' and continue with each INDENTED line x = 7 if x > 8: # if CONDITION is True, then execute block, otherwise skip block. print("Hello") # since x stores 7, this will skip print("I Am Sam.") # since x stores 7, this will skip elif x > 2: # elif condition is True AND previous if was False, execute block print("Hi") # since x stores 7, this will execute print("I am Sally.") # since x stores 7, this will execute else: # if all previous conditions are False, executer block. print("Yo") # since x stores 7, this will skip print("I'm Bob.") # since x stores 7, this will skip while x > 3: # repeat a block until condition becomes False print("Apples") x += -1 # Lists store multiple values a = [10, 30, 20, 90] # create a new list x = len(a) # x stores 4 (the length) b = a[0] # INDEX into the list, 0 is first value, b stores 10 c = a[3] # c stores 90 d = a[-1] # -1 is last value, d stores 90 e = a[1:3] # slice a from index 1 up to index 3, e stores [30, 20] a[1] = 50 # modify the second element in the list, a is now [10, 50, 20, 90] f = a + [5, 15] # f stores [10, 50, 20, 90, 5, 15], CONCATENATION not addition g = range(0, 4) # range function returns list 0 up to 4, g stores [0, 1, 2, 3] # For Loops for c in "Elephant!": # repeat block with c storing each character 1 at a time print(c) # prints one letter per line for x in [10, 30, 20]: print(x) # prints one number per line # Custom Functions def myfunc(a, b): # DEFINES a new function that takes 2 INPUT PARAMETER values c = 2 * a + b # executes only when function is called return c # RETURNS a value back to the calling code x = myfunc(10, 5) # Calls the myfunc() function, x stores return value 25 y = myfunc(1, 3) # Calls the myfunc() function, x stores return value 5
GGC