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diff --git a/basic-data-type/script.rst b/basic-data-type/script.rst deleted file mode 100644 index 22d4f3a..0000000 --- a/basic-data-type/script.rst +++ /dev/null @@ -1,553 +0,0 @@ -.. Objectives -.. ---------- - -.. At the end of this tutorial, you should know -- - -.. 1. Learn about Python Data Structures and Operators.(Remembering) -.. #.Use them to do basic operations.(Applying) - -.. Prerequisites -.. ------------- - -.. None - -.. Author : Amit Sethi - Internal Reviewer : - External Reviewer : - Checklist OK? : <put date stamp here, if OK> [2010-10-05] - -Hello friends and welcome to the tutorial on Basic Data types and operators -in Python. - -{{{ Show the slide containing title }}} - -{{{ Show the slide containing the outline slide }}} - -In this tutorial, we shall look at - -* Datatypes in Python - * Numbers - * Boolean - * Sequence -* Operators in Python - * Arithmetic Operators - * Boolean Operators - -* Python Sequence Data types - * list - * string - * tuple - -First we will explore python data structures in the domain of numbers. -There are three built-in data types in python to represent numbers. - -{{{ A slide to make a memory note of the different datatypes }}} - -These are: - - * int - * float - * complex - -Lets first talk about int. :: - - a = 13 - a - - -Now, we have our first int variable a. - - -If we now see :: - - type(a) - <type 'int'> - -This means that a is a type of int. There are lot of functions associated -with the int datatype, to manipulate it in different ways. These can be -explored by doing, :: - - a.<Tab> - -*int* datatype can hold integers of any size lets see this by an example. -:: - - b = 99999999999999999999 - b - -As you can see even when we put a value of 9 repeated 20 times python did -not complain. This is because python's int data-type can hold integers of any -size. - -Let us now look at the float data-type. - -Decimal numbers in python are represented by the float data-type :: - - p = 3.141592 - p - -If you notice the value of output of ``p`` isn't exactly equal to ``p``. -This is because computer saves floating point values in a specific format. -There is always an approximation. This is why we should never rely on -equality of floating point numbers in a program. - -The last data type in the list is complex number :: - - c = 3.2+4.6j - -as simple as that so essentialy its just a combination of two floats the -imaginary part being defined by j notation instead of i. Complex numbers -have a lot of functions specific to them. Let us look at these :: - - c.<Tab> - -Lets try some of them :: - - c.real - c.imag - -c.real gives the real part of the number and c.imag the imaginary. - -We can get the absolute value using the function :: - - abs(c) - - -Following is are exercises that you must do. - -%% %% Find the absolute value of 3+4j -:: - - abs(3+4j) - -%% %% What is the datatype of number 999999999999999999? Is it -not int? -:: - - Long - Big integers are internally stored in python - as Long datatype. - -Please, pause the video here. Do the exercises and then continue. - - -{{ Slide for showing Boolean datatypes }} - -Python also has Boolean as a built-in type. - -Try it out just type :: - - t = True - -note that T in true is capitalized. - -You can apply different Boolean operations on t now for example :: - - f = not t - f - f or t - f and t - - -The results are self explanatory. - -What if you want to apply one operator before another. - -Well you can use parenthesis for precedence. - -Lets write some piece of code to check this out.:: - - a=False - b=True - c=True - - -To check how precedence changes with parenthesis, we will try two -expressions and their evaluation. - -one :: - - (a and b) or c - -This expression gives the value True - -where as the expression :: - - a and (b or c) - -gives the value False. - - -Let's now look at some operators available in Python to manipulate -these data types. - -Python uses '+' for addition :: - - 23 + 74 - -'-' for subtraction :: - - 23 - 56 - -'*' for multiplication :: - - 45*76 - -'/' for division :: - - 384/16 - 8/3 - 8.0/3 - -When we did 8/3 the first case results in am integer -output as both the operands are integer however when -8.0/3 is used the answer is float as one of the operands is -float. - - -'%' for modulo operation :: - - 87 % 6 - -and two stars for a exponent. :: - - 7**8 - - -In case one wishes to use the current value of variable in which the result -is stored in the expression one can do that by putting the operator before -`equal to`. :: - - a=73 - a*=34 - -is same as :: - - a=a*34 - -and :: - - a/=23 - -is same as :: - - a=a/23 - -Following is are exercises that you must do. - -%% %% Using python find sqaure root of 3? - -%% %% Is 3**1/2 and 3**0.5 same - -Please, pause the video here. Do the exercises and then continue. - -:: - - 3**0.5 - -:: - No,One gives an int answer and the other float - - -Lets now discuss sequence data types in Python. Sequence data types -are those in which elements are kept in a sequential order and all the -elements are accessed using index numbers. - -{{{ slide introducing sequence datatype }}} - -The sequence datatypes in Python are :: - - * list - * string - * tuple - -The list type is a container that holds a number of other objects, in the -given order. - -We create our first list by typing :: - - num_list = [1, 2, 3, 4] - num_list - - -Items enclosed in square brackets separated by comma constitutes a list. - -Lists can store data of any type in them. - -We can have a list something like :: - - var_list = [1, 1.2, [1,2]] - var_list - -Lets look at another sequence data type, strings - -type :: - - greeting_string="hello" - - -greeting_string is now a string variable with the value "hello" - -{{{ All the different types of strings shown }}} - -Python strings can actually be defined in three different ways :: - - k='Single quote' - l="Let's see how to include a single quote" - m='''"Let's see how to include both"''' - -As you can see, single quotes are used as delimiters usually. - -When a string contains a single quote, double quotes are used as -delimiters. When a string quote contains both single and double quotes, -triple quotes are used as delimiters. - -The last in the list of sequence data types is tuple. - -To create a tuple we use normal brackets '(' unlike '[' for lists.:: - - num_tuple = (1, 2, 3, 4, 5, 6, 7, 8) - -Because of their sequential property there are certain functions and -operations we can apply to all of them. - - - -The first one is accessing. - -They can be accessed using index numbers :: - - num_list[2] - num_list[-1] - greeting_string[1] - greeting_string[3] - greeting_string[-2] - num_tuple[2] - num_tuple[-3] - - -Indexing starts from 0 from left to right and from -1 when accessing lists -in reverse. Thus num_list[2] refers to the third element 3. and greetings -[-2] is the second element from the end , that is 'l'. - - - -Addition gives a new sequence containing both sequences :: - - num_list+var_list - a_string="another string" - greeting_string+a_string - t2=(3,4,6,7) - num_tuple+t2 - -len function gives the length :: - - len(num_list) - len(greeting_string) - len(num_tuple) - -Prints the length the variable. - -We can check the containership of an element using the 'in' keyword :: - - 3 in num_list - 'H' in greeting_string - 2 in num_tuple - -We see that it gives True and False accordingly. - -Find maximum using max function and minimum using min:: - - max(num_tuple) - min(greeting_string) - -Get a sorted list :: - - sorted(num_list) - - -As a consequence of their order, we can access a group of elements in a -sequence, together. This is called slicing and striding. - -First lets discuss Slicing, - -Given a list :: - - j=[1,2,3,4,5,6] - -Lets say we want elements starting from 2 and ending in 5. - -For this we can do :: - - j[1:4] - -The syntax for slicing is, sequence variable name square bracket first -element index, colon, second element index. The last element however is not -included in the resultant list:: - - - j[:4] - -If first element is left blank default is from beginning and if last -element is left blank it means till the end. - -:: - - j[1:] - - j[:] - -This effectively is the whole list. - -Striding is similar to slicing except that the step size here is not one. - -Lets see by example :: - - new_num_list=[1,2,3,4,5,6,7,8,9,10] - new_num_list[1:8:2] - [2, 4, 6, 8] - -The colon two added in the end signifies all the alternate elements. This -is why we call this concept striding because we move through the list with -a particular stride or step. The step in this example being 2. - -We have talked about many similar features of lists, strings and tuples. -But there are many important features in lists that differ from strings and -tuples. Lets see this by example.:: - - new_num_list[1]=9 - greeting_string[1]='k' - -{{{ slide to show the error }}} - - - -As you can see while the first command executes with out a problem there is -an error on the second one. - -Now lets try :: - - new_tuple[1]=5 - -Its the same error. This is because strings and tuples share the property -of being immutable. We cannot change the value at a particular index just -by assigning a new value at that position. - - -We have looked at different types but we need to convert one data type into -another. Well lets one by one go through methods by which we can convert -one data type to other: - -We can convert all the number data types to one another :: - - i=34 - d=float(i) - d - -Python has built in functions int, float and complex to convert one number -type data structure to another. - -:: - - dec=2.34 - dec_con=int(dec) - dec_con - - -As you can see the decimal part of the number is simply stripped to get the -integer.:: - - com=2.3+4.2j - float(com) - com - -In case of complex number to floating point only the real value of complex -number is taken. - -Similarly we can convert list to tuple and tuple to list :: - - lst=[3,4,5,6] - tup=tuple(lst) - tupl=(3,23,4,56) - lst=list(tuple) - -However converting a string to a list and a list to a string is an -interesting problem. Let's say we have a string :: - - In: somestring="Is there a way to split on these spaces." - In: somestring.split() - - -This produces a list with the string split at whitespace. Similarly we can -split on some other character. - -:: - - In: otherstring="Tim,Amy,Stewy,Boss" - -How do we split on comma , simply pass it as argument :: - - In: otherstring.split(',') - -join function does the opposite. Joins a list to make a string.:: - - ','.join['List','joined','on','commas'] - -Thus we get a list joined on commas. Similarly we can do spaces.:: - - ' '.join['Now','on','spaces'] - -Note that the list has to be a list of strings to apply join operation. - -With this we come to the end of this tutorial . - -Following is an (are) exercise(s) that you must do. - - - -%% %% Check if 3 is an element of the list [1,7,5,3,4]. In case -it is change it to 21. -:: - l=[1,7,5,3,4] - 3 in l - l[3]=21 - l - -%% %% Convert the string "Elizabeth is queen of england" to -"Elizabeth is queen" -:: - - s="Elizabeth is queen of england" - stemp=s.split() - ' '.join(stemp[:3]) - -Please, pause the video here. Do the exercise(s) and then continue. - - -This brings us to the end of the tutorial. In this tutorial we have -discussed - -1. Number Datatypes , integer,float and complex -2. Boolean and datatype and operators -3. Sequence data types ,List,String and Tuple -4. Accesing sequence -5. Slicing sequences -6. Finding length , sorting and reversing operations on sequences. -7. Immutability. - -{{{ Show the "sponsored by FOSSEE" slide }}} - -This tutorial was created as a part of FOSSEE project, NME ICT, MHRD India - -Hope you have enjoyed and found it useful. - -Thank You. - - -.. - Local Variables: - mode: rst - indent-tabs-mode: nil - sentence-end-double-space: nil - fill-column: 75 - End: |