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diff --git a/getting-started-with-lists/script.rst b/getting-started-with-lists/script.rst deleted file mode 100644 index 5a084f9..0000000 --- a/getting-started-with-lists/script.rst +++ /dev/null @@ -1,242 +0,0 @@ -.. Objectives -.. ---------- - -.. By the end of this tutorial, you will be able to - -.. Create Lists. -.. Access List elements. -.. Append elemets to list -.. Delete list elemets - -.. 1. getting started with ipython - - - -.. Prerequisites -.. ------------- - -.. 1. getting started with strings -.. #. getting started with lists -.. #. basic datatypes - -.. Author : Amit - Internal Reviewer : Anoop Jacob Thomas <anoop@fossee.in> - External Reviewer : - Language Reviewer : Bhanukiran - Checklist OK? : <12-11-2010, Anand, OK> [2010-10-05] - -.. #[[Anoop: Slides contain only outline and summary - -Script ------- - {{{ Show the slide containing title }}} - -Hello friends and welcome to the tutorial on getting started with -lists. - - {{{ Show the slide containing the outline slide }}} - -In this tutorial we will be getting acquainted with a python data -structure called lists. We will learn :: - - * How to create lists - * Structure of lists - * Access list elements - * Append elements to lists - * Delete elements from lists - -List is a compound data type, it can contain data of mutually -different datatypes. List is also a sequence data type, all the -elements are arranged in a given order. - -.. #[[Anoop: "all the elements are in order and **there** order has a - meaning." - I guess something is wrong here, I am not able to - follow this.]] - -We will first create an empty list with no elements. On your IPython -shell type :: - - empty = [] - type(empty) - - -This is an empty list without any elements. - -.. #[[Anoop: the document has to be continous, without any - subheadings, removing * Filled lists]] - -Lets now see how to define a non-empty list. We do it as,:: - - nonempty = ['spam', 'eggs', 100, 1.234] - -Thus the simplest way of creating a list is typing out a sequence -of comma-separated values (or items) between two square brackets. - -As we can see lists can contain different kinds of data. In the -previous example 'spam' and 'eggs' are strings whereas 100 and 1.234 are -integer and float respectively. Thus we can put elements of different types in -lists including lists itself. This property makes lists heterogeneous -data structures. - -.. #[[Anoop: the sentence "Thus list themselves can be one of the - element types possible in lists" is not clear, rephrase it.]] - -Example :: - - listinlist=[[4,2,3,4],'and', 1, 2, 3, 4] - -We access an element of a list using its corresponding index. Index of -the first element of a list is 0. So for the list nonempty, nonempty[0] -gives the first element, nonempty[1] the second element and so on and -nonempty[3] the last element. :: - - nonempty[0] - nonempty[1] - nonempty[3] - -Following is an exercise that you must do. - -%% %% What happens when you do nonempty[-1]. - -Please, pause the video here. Do the exercise and then continue. - -.. #[[Anoop: was negative indices introduced earlier, if not may be we - can ask them to try out nonempty[-1] and see what happens and then - tell that it gives the last element in the list.]] - -As you can see you get the last element which is 1.234. - - -In python negative indices are used to access elements from the end:: - - nonempty[-1] - nonempty[-2] - nonempty[-4] - --1 gives the last element which is the 4th element , -2 second to last -and -4 gives the fourth from the last which, in this case, is the first element. - -We can append elements to the end of a list using the method append. :: - - nonempty.append('onemore') - nonempty - nonempty.append(6) - nonempty - -Following are exercises that you must do. - -%% %% What is the syntax to get the element 'and' -in the list,listinlist ? - - -%% %% How would you get 'and' using negative indices? - -Please, pause the video here. Do the exercise and then continue. - -The solution is on your screen - - -As we can see nonempty is appended with 'onemore' and 6 at the end. - -Using len function we can check the number of elements in the list -nonempty. In this case it is 6 :: - - len(nonempty) - - - -Just like we can append elements to a list we can also remove them. -There are two ways of doing it. One is by using index. :: - - del(nonempty[1]) - - - -deletes the element at index 1, i.e the second element of the -list, 'eggs'. The other way is removing element by content. Lets say -one wishes to delete 100 from nonempty list the syntax of the command -would be - -.. #[[Anoop: let x = [1,2,1,3] - now x.remove(x[2]) - still x is [2,1,3] so that is not the way to remove - element by index, it removed first occurrence of 1(by - content) and not based on index, so make necessary - changes]] - -:: - - nonempty.remove(100) - -but what if there were two 100's. To check that lets do a small -experiment. :: - - nonempty.append('spam') - nonempty - nonempty.remove('spam') - nonempty - -If we check now we will see that the first occurence 'spam' is removed -and therefore `remove` removes the first occurence of the element in the sequence -and leaves others untouched. - -One should remember this that while del removes by index number, -`remove` removes on the basis of content being passed on. For instance -if :: - - k = [1,2,1,3] - del([k[2]) - -gives us [1,2,3]. :: - - k.remove(x[2]) - -will give us [2,1,3]. Since it deletes the first occurence of what is -returned by x[2] which is 1. - - - - - - - -.. #[[Anoop: does it have two spams or two pythons?]] - -.. #[[Anoop: there are no exercises/solved problems in this script, - add them]] - -Following are exercises that you must do. - -%% %% Remove the third element from the list, listinlist. - -%% %% Remove 'and' from the list, listinlist. - -Please, pause the video here. Do the exercise and then continue. - - - -{{{Slide for Summary }}} - - -In this tutorial we came across a sequence data type called lists. :: - - * We learned how to create lists. - * How to access lists. - * Append elements to list. - * Delete Element from list. - * And Checking list length. - - - -{{{ show Sponsored by Fossee Slide }}} - -This tutorial was created as a part of FOSSEE project. - -I hope you found this tutorial useful. - -Thank You - -.. - * Author : Amit Sethi - * First Reviewer : - * Second Reviewer : Nishanth |