 Python Page 3 - Python Conditionals, Lists, Dictionaries, and Operators |
Lists - PythonIn our last article we learned how to get input from the user, store data in a variable, and work with some basic operators to manipulate that data. In this article we will learn to use Conditional Statements and possibly create functions. So wipe that mustard off your chin, clean the dishes, and let's get to work.
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We covered variables in our previous tutorial. Now we are going to cover Lists. You may have heard of arrays in other programming languages; a list is the Python equivalent. Whereas a variable holds a value, a list holds a bunch of values. Each value can be referenced by its position in the list, starting with the number 0 and moving forward. Here is an example: #!/usr/local/bin/python suess = ['I', 'like', 'green', 'eggs', 'and', 'spam'] print suess print suess[0] The above program creates a List named suess, and assigns a bunch of data to it, separating each piece of data with a comma (,). It then prints the entire List, and finally prints one element in the list, in this case the first one (0). Here it is! I like green eggs and spam I You can also change the value of an element in a list later on: #!/usr/local/bin/python suess = ['I', 'like', 'green', 'eggs', 'and', 'spam'] print “This is the data in the list originally:”, suess suess[5] = 'ham' print “This is the data in the list after the lawsuit:”, suess Again, we fill up our suess List with data. Then we print it. Next, we change one specific element in the suess List from spam to ham (remember the first element is 0, so spam would be element 5). We then print it out with the new data, like so: This is the data in the list originally: I like green eggs and spam This is the data in the list after the lawsuit: I like green eggs and ham The number of elements in a list is not a set number; you can add and delete elements until the cows come home. And let's face it, once those cows have had a taste of the good life, they are never returning to your crummy studio apartment. #!/usr/local/bin/python suess = ['I', 'like', 'green', 'eggs', 'and', 'spam'] print “This is the data in the list originally:”, suess suess[6] = 'yummy!' print 'Here is the list with appended elements:', suess This results in: This is the data in the list originally: I like green eggs and spam Here is the list with appended elements: I like green eggs and spam yummy!
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