Python如何有效地使用迭代

# A C-style way of accessing list elements
cars = ["Aston", "Audi", "McLaren"]
i = 0
while (i < len(cars)):
    print(cars[i])
    i += 1

# Accessing items using for-in loop
cars = ["Aston", "Audi", "McLaren"]
for x in cars:
    print(x)

# Accessing items using indexes and for-in
cars = ["Aston", "Audi", "McLaren"]
for i in range(len(cars)):
    print(cars[i])

# Accessing items using enumerate()
cars = ["Aston", "Audi", "McLaren "]
for i, x in enumerate(cars):
    print(x)

# Accessing items and indexes enumerate()
cars = ["Aston" , "Audi", "McLaren "]
for x in enumerate(cars):
    print (x[0], x[1])

# Printing return value of enumerate()
cars = ["Aston" , "Audi", "McLaren "]
print (enumerate(cars))

# demonstrating the use of start in enumerate
cars = ["Aston" , "Audi", "McLaren "]
for x in enumerate(cars, start=1):
    print (x[0], x[1])

# Two separate lists
cars = ["Aston", "Audi", "McLaren"]
accessories = ["GPS kit", "Car repair-tool kit"]
# Single dictionary holds prices of cars and
# its accessories.
# First three items store prices of cars and
# next two items store prices of accessories.
prices = {1: "570000$", 2: "68000$", 3: "450000$",
          4: "8900$", 5: "4500$"}
# Printing prices of cars
for index, c in enumerate(cars, start=1):
    print("Car: %s Price: %s" % (c, prices[index]))
# Printing prices of accessories
for index, a in enumerate(accessories, start=1):
    print("Accessory: %s Price: %s"
          % (a, prices[index+len(cars)]))

# Python program to demonstrate the working of zip
# Two separate lists
cars = ["Aston", "Audi", "McLaren"]
accessories = ["GPS", "Car Repair Kit",
               "Dolby sound kit"]
# Combining lists and printing
for c, a in zip(cars, accessories):
    print("Car: %s, Accessory required: %s" % (c, a))

# Python program to demonstrate unzip (reverse
# of zip)using * with zip function
# Unzip lists
l1,l2 = zip(*[('Aston', 'GPS'),
              ('Audi', 'Car Repair'),
              ('McLaren', 'Dolby sound kit')
           ])
# Printing unzipped lists     
print(l1)
print(l2)