Numbers ------- Addition >>> 2 + 2 4 Subtraction >>> 0 - 2 -2 Multiplication >>> 2 * 3 6 Division >>> 4 / 2 2 >>> 1 / 2 0 Integer divison produces an integer. You need a number that knows about the decimal point to get a decimal out of division: >>> 1.0 / 2 0.5 >>> float(1) / 2 0.5 Remainder >>> 4 % 2 0 >>> 4 % 3 1 Types >>> type(1) >>> type(1.0) Strings ------- >>> "Hello" 'Hello' Printing strings >>> print "Hello" Hello String concatenation >>> print "Hello" + "World" HelloWorld >>> print "Hello", "World" Hello World Printing different data types together >>> print "Hello", "World", 1 Hello World 1 String formatting >>> print "Hello %d" % (1,) Hello 1 >>> print "Hello %s" % ("World",) Hello World >>> type("Hello") Lists ----- List initialization >>> my_list = list() >>> my_list [] >>> your_list = [] >>> your_list [] >>> her_list = ["a", "b", "c", "d", "e", "f", "g", "h"] >>> her_list ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h'] Access and adding elements to a list >>> len(my_list) 0 >>> my_list[0] Traceback (most recent call last): File "", line 1, in IndexError: list index out of range >>> my_list.append("Alice") >>> my_list ['Alice'] >>> len(my_list) 1 >>> my_list[0] 'Alice' >>> my_list.insert(0, "Amy") >>> my_list ['Amy', 'Alice'] Changing elements in a list >>> your_list.append("apples") >>> your_list[0] 'apples' >>> your_list[0] = "bananas" >>> your_list ['bananas'] Slicing lists >>> her_list ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h'] >>> her_list[0] 'a' >>> her_list[0:3] ['a', 'b', 'c'] >>> her_list[:3] ['a', 'b', 'c'] >>> her_list[-1] 'h' >>> her_list[5:] ['f', 'g', 'h'] >>> her_list[:] ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h'] Sharing versus copying: Sharing >>> my_list ['Alice'] >>> your_list = my_list >>> your_list ['Alice'] >>> my_list[0] = "Bob" >>> my_list ['Bob'] >>> your_list ['Bob'] Copying >>> my_list ['Alice'] >>> your_list = my_list[:] >>> my_list[0] = "Bob" >>> my_list ['Bob'] >>> your_list ['Alice'] Strings are lists too >>> my_string = "Hello World" >>> my_string[0] 'H' >>> my_string[:5] 'Hello' >>> my_string[6:] 'World' >>> my_string[6:] = "Jessica" Traceback (most recent call last): File "", line 1, in TypeError: 'str' object does not support item assignment >>> my_string = my_string[:6] + "Jessica" >>> my_string 'Hello Jessica' >>> type(my_list) Dictionaries ------------ Dictionary initialization >>> my_dict = dict() >>> your_dict = {} >>> her_dict = {"Alice" : "chocolate", "Bob" : "strawberry", "Cara" : "mint chip"} >>> her_dict {'Bob': 'strawberry', 'Cara': 'mint chip', 'Alice': 'chocolate'} Adding elements >>> her_dict["Dora"] = "vanilla" >>> her_dict {'Bob': 'strawberry', 'Cara': 'mint chip', 'Dora': 'vanilla', 'Alice': 'chocolate'} Accessing elements >>> her_dict["Alice"] 'chocolate' >>> her_dict.get("Alice") 'chocolate' >>> her_dict["Eve"] Traceback (most recent call last): File "", line 1, in KeyError: 'Eve' >>> "Eve" in her_dict False >>> "Alice" in her_dict True >>> her_dict.get("Eve") >>> her_dict.get("Alice") 'coconut' Changing elements >>> her_dict["Alice"] = "coconut" >>> her_dict {'Bob': 'strawberry', 'Cara': 'mint chip', 'Dora': 'vanilla', 'Alice': 'coconut'} >>> type(my_dict) Tuples ------ Initialization >>> tuple() () >>> ("apple", "oranges", "bananas") ('apple', 'oranges', 'bananas') >>> my_tuple = ("apple", "oranges", "bananas") Accessing elements of a tuple: just like lists >>> my_tuple = ("apple", "oranges", "bananas") >>> my_tuple[0] 'apple' >>> len(my_tuple) 3 >>> my_tuple[-1] 'bananas' >>> my_tuple[:2] ('apple', 'oranges') Adding or changing elements of a tuple: can't do it! Not a mutable data type. >>> my_tuple[:2] ('apple', 'oranges') >>> my_tuple[0] = "figs" Traceback (most recent call last): File "", line 1, in TypeError: 'tuple' object does not support item assignment >>> type(my_tuple)