This section explains a bit on how to use basic operators in Python.
Just as any other programming languages, the addition, subtraction, multiplication, and division operators can be used with numbers.
number = 1 + 2 * 3 / 4.0
Try to predict what the answer will be. Does python follow order of operations?
Another operator available is the modulo (%) operator, which returns the integer remainder of the division. dividend % divisor = remainder.
remainder = 11 % 3
Using two multiplication symbols makes a power relationship.
squared = 7 ** 2 cubed = 2 ** 3
Python supports concatenating strings using the addition operator:
helloworld = "hello" + " " + "world"
Python also supports multiplying strings to form a string with a repeating sequence:
lotsofhellos = "hello" * 10
Lists can be joined with the addition operators:
even_numbers = [2,4,6,8] odd_numbers = [1,3,5,7] all_numbers = odd_numbers + even_numbers
Just as in strings, Python supports forming new lists with a repeating sequence using the multiplication operator:
print [1,2,3] * 3
The target of this exercise is to create two lists called x_list and y_list, which contain 10 instances of the variables x and y, respectively. You are also required to create a list called "big_list", which contains the variables "x" and "y", 10 times each, by concatenating the two lists you have created.
x = object() y = object() # change this code x_list = [x] y_list = [y] big_list =  print "x_list contains %d objects" % len(x_list) print "y_list contains %d objects" % len(y_list) print "big_list contains %d objects" % len(big_list) # testing code if x_list.count(x) == 10 and y_list.count(y) == 10: print "Almost there..." if big_list.count(x) == 10 and big_list.count(y) == 10: print "Great!"
x_list contains 10 objects y_list contains 10 objects big_list contains 20 objects Almost there... Great!