Python/C3/Basic-datatypes-and-operators/English-timed
From Script | Spoken-Tutorial
| Time | Narration |
| 00:00 | Hello friends and welcome to the tutorial on 'Basic Data types and operators' in Python. |
| 00:07 | At the end of this tutorial, you will be able to, Know the Datatypes in Python
Numbers, Boolean, Sequence, Learn about the Operators in Python Arithmetic Operators, Boolean Operators, Know the Python Sequence Data types list, string, tuple |
| 00:28 | First we will explore python data structures in the domain of numbers. |
| 00:34 | There are three built-in data types in python to represent numbers. |
| 00:38 | These are: int,float, complex |
| 00:43 | Let us first invoke our ipython interpreter |
| 00:48 | So type ipython in your command and hit enter |
| 00:52 | Lets first talk about int. |
| 00:54 | So type a=13 |
| 01:00 | Then type a and you can see the output. |
| 01:03 | Now, we have our first int variable a. |
| 01:07 | If we now see Type command type within brackets a then we see the output int |
| 01:17 | This means that 'a' is a type of int. |
| 01:22 | There are lot of functions associated with the int datatype, to manipulate it in different ways. |
| 01:30 | These can be explored by doing, a dot tab |
| 01:40 | int datatype can hold integers of any size lets see this by an example. |
| 01:48 | So type b= couple of 9 or some data, then type b and you can see the output. |
| 02:02 | As you can see, even when we put a value of 9 repeated 20 times, python did not complain. |
| 02:12 | This is because python's int data-type can hold integers of any size. |
| 02:17 | Let us now look at the float data-type. |
| 02:21 | Decimal numbers in python are represented by the float data-type |
| 02:25 | So type p = 3 point 141592,then type p. |
| 02:41 | Then if you notice the value of output of p isn't exactly equal to p. |
| 02:48 | This is because computer saves floating point values in a specific format. |
| 02:54 | There is always an approximation. |
| 02:57 | This is why we should never rely on equality of floating point numbers in a program. |
| 03:05 | The last data type in the list is complex number |
| 03:09 | So type c = 3 point 2 plus 4 point 6j |
| 03:18 | it's just a combination of two floats the imaginary part being defined by j notation instead of i. |
| 03:25 | Complex numbers have a lot of functions specific to them. |
| 03:29 | Let us look at these |
| 03:31 | So type c dot tab, so can get the output. |
| 03:37 | So let's try some of them c.real then c.imag |
| 03:49 | c.real gives the real part of the number and c.imag the imaginary. |
| 03:56 | We can get the absolute value using the function abs within bracket c |
| 04:06 | Now pause the video here, and try out the following exercise and resume the video. |
| 04:15 | Find the absolute value of 3+4j Switch to terminal for solution |
| 04:27 | So type abs within bracket 3+4j |
| 04:34 | Thus we get the absolute value of the expression. |
| 04:37 | Let us do 1 more exercise of a similar type. |
| 04:39 | Pause the video here, and try out the following exercise and resume the video. |
| 04:45 | What is the data type of number 29 that is a couple of 999999999999999999? after 20 So Is it not int? |
| 05:00 | The solution is on your screen. |
| 05:02 | The data type of this number is long though it is an integer. |
| 05:07 | But big integers are internally stored in python as Long data type. |
| 05:13 | Python also has Boolean as a built-in type. |
| 05:18 | To Try it out, just type in the terminal t=True. |
| 05:28 | note that T in true is capitalized. |
| 05:34 | You can apply different Boolean operations on t now for example |
| 05:40 | Try out f = not t enter
f f or t f and t |
| 05:59 | The results are self explanatory. |
| 06:01 | What if you want to apply one operator before another. |
| 06:05 | Well you can use parenthesis for precedence. |
| 06:10 | Lets write some piece of code to check this out. |
| 06:13 | So type a =False
b=True c=True |
| 06:24 | To check how precedence changes with parenthesis, we will try two expressions and their evaluation. |
| 06:33 | The first one within bracket a and b or c then hit enter |
| 06:44 | This expression gives the value True where as the expression a and within brackets b or c |
| 07:01 | and that gives the value False. |
| 07:04 | Let's now look at some operators available in Python to manipulate these data types. |
| 07:09 | Python uses 'plus' sign for addition |
| 07:13 | So type 23 + 74 you can see the added value |
| 07:19 | And 'minus' sign for subtraction |
| 07:24 | 23 - 56 |
| 07:27 | '*' (star) sign for multiplication |
| 07:33 | '/'(back slash) for division |
| 07:37 | For example we can try out 384 by 16
8 by 3 and for the decimal one we can try 8 point 0 by 3. |
| 07:57 | Note that, when we did 8/3 the first case results in an integer output as both the operands are integer however when 8 point 0/3 is used the answer is float as one of the operands is float. |
| 08:16 | Let us move ahead with the operators. '%' (percentage) sign for modulo operation |
| 08:23 | So type 87 modulo 6 and hit enter |
| 08:29 | and two stars for a exponent. |
| 08:32 | So type 7 star star 8 and hit enter |
| 08:38 | It is said 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. |
| 08:49 | So you can say a=73 a star=34 |
| 08:59 | The above expression is same as, you can try out by typing a=a star 34 and hit enter |
| 09:12 | and a backslash =23 |
| 09:21 | Pause the video here, and try out the following exercise and resume the video. |
| 09:25 | Using python find the square root of 3. |
| 09:29 | The solution is on your screen. |
| 09:33 | 3 star star 0.5 gives the square root of 3. |
| 09:39 | Now, ls 3 star star 1 slash 2 and 3 star star 0 point 5 same? |
| 09:54 | Now switch to terminal. |
| 09:57 | And let us try both these operations. |
| 10:00 | So type 3 star star 0 point 5 and hit enter 3 star star 1 slash 2 and hit enter |
| 10:15 | As you can see,the first operation gives an integer, whereas the second one gives a float. |
| 10:19 | Hence,though both mean the same,they give different outputs. |
| 10:24 | Let us now discuss sequence data types in Python. |
| 10:27 | Sequence data types are those in which elements are kept in a sequential order and all the elements are accessed using index numbers. |
| 10:38 | The sequence data types in Python are list, string, tuple |
| 10:43 | The list type is a container that holds a number of other objects, in the given order. |
| 10:51 | We create our first list by typing |
| 10:55 | So type num underscore list = within square bracket 1 comma 2 comma 3 comma 4 num underscore list |
| 11:08 | Items enclosed in square brackets separated by comma constitutes a list. |
| 11:14 | Lists can store data of any type in them. |
| 11:18 | We have a list something like var underscore list = within square bracket 1 comma 1 point 2 comma then again within square bracket 1 comma 2 var underscore list |
| 11:45 | Lets look at another sequence data type, strings |
| 11:49 | So you can type greeting underscore string= within double quotes hello |
| 12:01 | greeting_string is now a string variable with the value "hello" |
| 12:07 | Python strings can actually be defined in three different ways |
| 12:12 | k= single quote write Single quote
l=Let's see how to include a single quote m=within three single quotes and in double quotes Let's see how to include both |
| 12:34 | As you can see, single quotes are used as delimiters usually. |
| 12:38 | When a string contains a single quote, double quotes are used as delimiters. |
| 12:44 | When a string quote contains both single and double quotes, triple quotes are used as delimiters. |
| 12:55 | The last in the list of sequence data types is tuple. |
| 12:59 | To create a tuple we use normal brackets '(' unlike square bracket '[' for lists. |
| 13:07 | So you can type num underscore tuple = within bracket 1 to 8 separated by comma |
| 13:18 | Because of their sequential property there are certain functions and operations we can apply to all of them. |
| 13:25 | The first one is accessing. |
| 13:28 | They can be using index numbers. |
| 13:31 | So type in terminal num underscore list within square bracket 2
num underscore list within square bracket -1, greeting underscore string within bracket 1 greeting underscore string within square bracket 3, greeting underscore string within square bracket -2 num underscore tuple within square bracket 2,num underscore tuple within square bracket -3 |
| 14:08 | Indexing starts from 0, from left to right and from -1 when accessing lists in reverse. |
| 14:14 | Thus num underscore list[2] refers to the third element 3. and greetings [-2] is the second element from the end , that is 'l'. |
| 14:26 | Addition gives a new sequence containing both sequences |
| 14:30 | So type num underscore list + var underscore list in terminal.
Then a underscore string= and in double quote another string greeting underscore string+a underscore string t2= 3 4 6 7 separated by comma in bracket num underscore tuple+t2 |
| 15:17 | len function gives the length |
| 15:20 | So you can type len within bracket num underscore list
len within bracket greeting underscore string len within bracket num underscore tuple |
| 15:43 | We can check the container ship of an element using the 'in' keyword |
| 15:50 | So you can type in terminal and check so that you can see the difference.So type
3 in num underscore list Then type in single quotes 'H' in greeting underscore string 2 in num underscore tuple |
| 16:15 | We see that it gives True and False accordingly. |
| 16:18 | Find maximum using max function and minimum using min |
| 16:23 | Check that by typing in terminal max within bracket num underscore tuple
min within bracket greeting underscore string |
| 16:39 | Get a sorted list |
| 16:42 | So you can type sorted within bracket num underscore list |
| 16:50 | As a consequence of their order, we can access a group of elements in a sequence, together. |
| 16:57 | This is called slicing and striding. |
| 17:00 | First lets discuss Slicing, |
| 17:02 | Given a list j= within square bracket 1 to 6 |
| 17:09 | Lets say we want elements starting from 2 and ending in 5. |
| 17:14 | For this we can do j within square bracket 1 colon 4 |
| 17:24 | The syntax for slicing is, sequence variable name, square bracket, first element index, colon, second element index. |
| 17:36 | The first element however is not included in the resultant list |
| 17:39 | So you can type j within square bracket colon 4 |
| 17:49 | If first element is left blank default is from beginning and if last element is left blank it means till the end. |
| 18:14 | So you can type under the terminal
j within square bracket 1 colon j within bracket colon |
| 18:30 | This effectively is the whole list. |
| 18:33 | Striding is similar to slicing except that the step size here is not one. |
| 18:39 | So let us see an example |
| 18:41 | So type new underscore num underscore list=1 to 10 separated by commas in square bracket new underscore num underscore list within square bracket 1 colon 8 colon 2 then on the other line within square bracket 2 4 6 8 separated by commas that will be the output. |
| 19:07 | The, colon two, added in the end signifies all the alternate elements. |
| 19:15 | This is why we call this concept striding because we move through the list with a particular stride or step. |
| 19:23 | The step in this example being 2. |
| 19:25 | We have talked about many similar features of lists, strings and tuples. |
| 19:32 | But there are many important features in lists that differ from strings and tuples. |
| 19:37 | Lets see this by example. |
| 19:40 | Type new underscore num underscore list within square bracket[1]=9
greeting underscore string within square bracket 1 =within single quote k |
| 19:59 | We can see an error |
| 20:03 | As you can see while the first command executes with out a problem there is an error on the second one. |
| 20:10 | Now lets try new underscore tuple within square bracket 1=5 |
| 20:19 | Its showing the same error. |
| 20:23 | This is because strings and tuples share the property of being immutable. |
| 20:28 | We cannot change the value at a particular index just by assigning a new value at that position. |
| 20:34 | We have looked at different types but we need to convert one data type into another. |
| 20:39 | Well lets one by one go through methods by which we can convert one data type to other |
| 20:45 | So type i=34
d=float within bracket i So type d |
| 21:00 | Python has built in functions int, float and complex to convert one number type data structure to another. |
| 21:08 | So type dec=2.34
dec underscore con=int(dec) dec underscore con |
| 21:29 | As you can see the decimal part of the number is simply stripped to get the integer. |
| 21:35 | So type com=2.3+4.2j float within bracket com |
| 21:56 | So here we are getting another error |
| 22:05 | So here the error can be solved by your side. |
| 22:10 | Similarly we can convert list to tuple and tuple to list. |
| 22:15 | For that type lst= 3 4 5 6 separated by comma
tup=tuple within bracket lst Then type lst Then type tupl=3 comma 23 comma 4 comma 56 in bracket lst=list within bracket tuple Then type tuple |
| 22:54 | However converting a string to a list and a list to a string is an interesting problem. |
| 22:59 | Let's say we have a string some string= within double quote Is there a way to split on these spaces. some string.split() function, so it will spilt.Hit by command. |
| 23:28 | This produces a list with the string split at white space. |
| 23:33 | Similarly we can split on some other character. |
| 22:37 | So you can type other string=within double quote Tim comma Amy comma Stewy comma Boss |
| 23:48 | How do we split on comma , simply pass it as argument |
| 23:56 | So you can type on the terminal other string.split within bracket comma in single quote and hit enter |
| 24:06 | join function does the opposite. |
| 24:10 | Joins a list to make a string. |
| 24:14 | So you can type l1=within square bracket List comma joined comma on comma commas,all are in single quote
Then type , within single quote comma .join within bracket l1 |
| 25:02 | Thus we get a list joined on commas. |
| 25:05 | Similarly we can do spaces. |
| 25:07 | So you can type l2=Within square brackets in single quote Now comma on comma spaces. And we can type in single quote space.join within bracket l2, so you will get out put. |
| 25:27 | Note that the list has to be a list of strings to apply join operation. |
| 25:32 | Pause the video here, try out the following exercise and resume the video. |
| 25:38 | Check if 3 is an element of the list [1 comma 7 comma 5 comma 3 comma 4]. In case it is change it to 21. |
| 25:56 | Switch to the terminal for solution |
| 26:00 | Type l=[1 comma 7 comma 5 comma 3 comma 4
3 in l l in square bracket 3=21 l |
| 26:22 | Let us solve one more exercise. |
| 26:24 | Pause the video here, do the exercise and resume the video. |
| 26:31 | Convert the string "Elizabeth is queen of England" to "Elizabeth is queen" |
| 26:39 | Switch to the terminal for solution. |
| 26:43 | So s=Elizabeth is queen of England in double quotes
stemp=s.split() within single quote space.join within bracket stemp within square bracket colon 3 and hit enter |
| 27:07 | As you can see, we have easily removed the unwanted words. |
| 27:11 | This brings us to the end of the tutorial. |
| 27:14 | In this tutorial, we have learnt to, 1. Understand the number Data types -- integer,float and complex. |
| 27:21 | 2. Know the boolean data type and operators +, backslash, percent that is modulo and * for multiplication . |
| 27:33 | 3. use the sequence data types -- List,String and Tuple. |
| 27:36 | 4. Slice sequences by using the row and column numbers. |
| 27:41 | 5. Split and join a list using split() and join() function respectively. |
| 27:49 | 6. Convert to string to tuple and vice-versa. |
| 27:54 | Here are some self assessment questions for you to solve |
| 27:58 | 1. What is the major difference between tuples and lists? |
| 28:02 | 2. Split this string on white spaces |
| 28:05 | string="Split this string on white spaces" |
| 28:09 | And the answers, |
| 28:12 | 1. The major difference between tuples and lists is that Tuples are immutable while lists are not. |
| 28:20 | 2. To split the string on white space, we use the function `` split`` without any argument |
| 28:26 | string.split() function |
| 28:29 | Hope you have enjoyed this tutorial and found it useful. |
| 28:34 | Thank You. |
