Python/C3/Statistics/English-timed - Revision history

PoojaMoolya at 06:12, 27 March 2017

2017-03-27T06:12:10Z

PoojaMoolya at 11:51, 20 February 2017

2017-02-20T11:51:00Z

Gaurav at 09:07, 10 July 2014

2014-07-10T09:07:04Z

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Sneha at 05:53, 18 March 2013

2013-03-18T05:53:58Z

Sneha at 05:31, 18 March 2013

2013-03-18T05:31:54Z

Minal: Created page with '{| border=1 !Timing !Narration |- | 0:00 | Hello friends and welcome to the tutorial on 'Statistics' using Python. |- | 0:06 | At the end of this tutorial,you will be able to, …'

2013-01-02T11:01:22Z

Created page with '{| border=1 !Timing !Narration |- | 0:00 | Hello friends and welcome to the tutorial on 'Statistics' using Python. |- | 0:06 | At the end of this tutorial,you will be able to, …'

New page

{| border=1
!Timing
!Narration
|-
| 0:00
| Hello friends and welcome to the tutorial on 'Statistics' using Python.

|-
| 0:06
| At the end of this tutorial,you will be able to,

# Do statistical operations in Python
# Sum a set of numbers
# Find their mean,median and standard deviation

|-
| 0:17
| Before beginning this tutorial,we would suggest you to complete the tutorial on

|-
|0:21
|"Loading Data from files" "Getting started with Lists" and "Accessing Pieces of Arrays".

|-
|0:29
| Now, type in terminal ipython space hyphen pylab.

|-
|0:38
| For this tutorial, we will use data file that is at the path slash home slash fossee slash sslc2 dot txt.

|-
|0:47
|It contains record of students and their performance in one of the State Secondary Board Examination.

|-
|0:53
|It has 180,000 lines of record.

|-
|0:57
|We are going to read it and process this data.

|-
|1:02
| We can see the content of file by double clicking on it.

|-
|1:06
|It might take some time to open since it is quite a large file.

|-
|1:11
| Please don't edit the data since it has a particular structure.

|-
| 1:15
| To check the contents of the file, we use the cat command.

|-
| 1:18
| So type cat space slash home slash fossee slash sslc2 dot txt. Hit enter.

|-
| 1:31
| Each line in the file is a set of 11 fields separated by semi-colons.

|-
|1:38
| Consider a sample line from this file.

|-
|1:43
| A semicolon 015163 semicolon JOSEPH RAJ S semicolon 083 semicolon 042 semicolon 47 semicolon 00 semicolon 72 semicolon 244 and three semicolons in a row.

|-
|2:11
|The following are the fields in any given line.

|-
|2:16
| * Region Code which is 'A' * Roll Number 015163 * Name JOSEPH RAJ S * Marks of 5 subjects: ** English 083 ** Hindi 042 ** Maths 47 **
Science 35 **Social Science 72 and Total marks 244

|-
| 2:42
| Lets load this data as an array and then run various functions on it.

|-
|2:48
|To get the data as an array, we use the loadtxt command

|-
|2:53
|So type on the terminal L is equal to loadtxt within brackets , single quotes slash home slash fossee slash sslc2 dot txt comma usecols is equal to within brackets 3,4,5,6,7 comma delimiter is equal to within single quotes semicolon) and hit Enter.

|-
| 3:45
| We get our output in the form of an array dot loadtxt function.

|-
|3:57
|Now we have an error.

|-
|3:58
|We have to type loadtxt before the brackets.

|-
|4:09
| Delimiter specifies the kind of character, that the fields of data separated by usecols specifies the columns to be used.

|-
|4:19
| So within brackets 3,4,5,6,7 loads those columns.

|-
|4:26
|The 'comma' is added because usecols is a sequence.

|-
|4:31
|As we can see L is an array.

|-
|4:35
| We can get the shape of this array using in the terminal we can type L dot shape and hit Enter.

|-
| 4:43
| We get a tuple stating the numbers of rows and columns respectively.

|-
|4:50
|Lets start applying statistical operations on these.

|-
|4:55
|We will start with the most basic, summing.

|-
|4:59
| How do you find the sum of marks of all subjects for the first student.

|-
| 5:04
| As we know from our knowledge of accessing pieces of arrays, to access the first row, we will do in terminal type L square brackets 0 comma colon.

|-
| 5:19
| Now to sum this we can say totalmarks is equal to sum within brackets L within square brackets 0 comma colon. Hit Enter.Then totalmarks. Then again Enter.

|-
| 5:47
| Now to get the mean we can divide the totalmarks by the length.

|-
|5:52
|So type totalmarks slash len within brackets L in square brackets 0 comma colon.

|-
|6:10
|Or simply use the function mean.

|-
|6:13
|For that type mean within brackets L and in square brackets 0 comma colon and hit Enter.

|-
|6:31
| But we have such a large data set and calculating the mean for each student one by one is impossible.

|-
|6:38
| Is there a way to reduce the work.

|-
|6:40
|For this we will look into the documentation of mean

|-
|6:42
|So for that type mean question mark in the terminal.

|-
| 6:49
| As we know L is a two dimensional array.

|-
|6:52
| We can calculate the mean across each of the axis of the array.

|-
|6:57
| The axis of rows is referred by number 0 and columns by 1.

|-
|7:02
| So to calculate mean across all columns, we will pass extra parameter 1 for the axis.

|-
|7:07
|So type mean within brackets L comma 1 and hit Enter.

|-
| 7:17
| L here, is a two dimensional array.

|-
|7:20
|Similarly to calculate average marks scored by all the students for each subject can be calculated using mean within brackets L comma 0.

|-
| 7:36
| Next, let us calculate the median of English marks for the all the students.

|-
|7:41
| We can access English marks of all students using L in square brackets colon comma zero and hit Enter.

|-
| 7:53
| To get the median we will simply use the function <tt>median</tt>.

|-
|7:57
|So type median within brackets L square brackets colon comma 0 .

|-
| 8:17
| For all the subjects we can use the same syntax as mean and calculate median across all rows using median

|-
|8:25
|So type median in brackets L comma 0 and hit Enter.

|-
| 8:35
| Similarly to calculate standard deviation for English we will use the function <tt>std</tt>

|-
|8:41
|So type std, in brackets L and in square brackets colon comma 0 and hit Enter

|-
| 8:57
| and for all rows, we do std within brackets L comma 0.

|-
| 9:08
| Pause the video here, try out the following exercise and resume the video.

|-
| 9:13
| In the given file football dot txt at path slash home slash fossee slash football dot txt , one column is player name,second is goals at home and third goals away.

|-
|9:28
|1.Find the total goals for each player

|-
|9:33
| 2.Mean of home and away goals

|-
|9:37
|3.Standard deviation of home and away goals

|-
| 9:46
| This is the required data.

|-
|9:49
|For that open the football dot txt file.

|-
|9:54
| The solution is on your screen.

|-
| 10:00
| This brings us to the end of the tutorial.

|-
|10:03
| In this tutorial,we have learnt to,

|-
|10:07
|1. Do the standard statistical operations sum , mean median and standard deviation in Python.

|-
|10:14
|2. Combine text loading and the statistical operation to solve real world problems.

|-
| 10:24
| Here are some self assessment questions for you to solve

|-
|10:27
|1. <nowiki>Given a two dimensional list, two_dimensional_list is equal to within square brackets [3,5,8,2,1],within another square brackets [4,3,6,2,1] how do we calculate the mean of each row?</nowiki>

|-
|10:49
| 2.<nowiki>Calculate the median of the given list? student_marks is equal to within square brackets 74,78,56,87,91,82</nowiki>

|-
|11:03
|And the third question is Suppose there is a file with 6 columns but we wish to load text only in columns 2,3,4,5. How do we specify that?

|-
| 11:16
| And the answers,

|-
|11:20
|1. To get the mean of each row, we just pass 1 as the second parameter to the function <tt>mean</tt>.

|-
|11:29
| So we have to type mean within brackets two_dimensional_list comma 1

|-
|11:37
|2. We use the function <tt>median</tt> to calculate the median of the list

|-
|11:42
| by typing median within brackets student_marks.

|-
|11:47
|And the final one To specify the particular columns of a file, we use the parameter usecols is equal to 2,3,4,5.

|-
| 12:01
| Hope you have enjoyed this tutorial and found it useful.

|-
|12:05
| Thank you!

|}

@@ Line 80: / Line 80: @@
 |-
 |02:16
-| * Region Code which is 'A' * Roll Number 015163 * Name JOSEPH RAJ S * Marks of 5 subjects: ** English 083 ** Hindi 042 ** Maths 47 **
+| Region Code which is 'A' * Roll Number 015163 * Name JOSEPH RAJ S * Marks of 5 subjects: ** English 083 ** Hindi 042 ** Maths 47 **
 Science 35  **Social Science 72 and Total marks 244
@@ Line 96: / Line 96: @@
 |-
-|  03:45
+| 03:45
 | We get our output in the form of an array dot loadtxt function.
 |-
 |03:57
-|Now we got an error.
+|Now we got an error. We have to type loadtxt before the brackets.
-−
-|-
-|03:58
-|We have to type loadtxt before the brackets.
 |-
@@ Line 184: / Line 180: @@
 |-
-|  06:49
+|06:49
 | As we know L is a two dimensional array.
@@ Line 204: / Line 200: @@
 |-
-|  07:17
+|07:17
 | L here, is a two dimensional array.
@@ Line 212: / Line 208: @@
 |-
-|  07:36
+|07:36
 | Next, let us calculate the median of English marks for the all the students.
@@ Line 220: / Line 216: @@
 |-
-|  07:53
+| 07:53
 | To get the median we will simply use the function median.

@@ Line 10: / Line 10: @@
 | 00:06
 | At the end of this tutorial,you will be able to,
 Do statistical operations in Python
-# Do statistical operations in Python
+Sum a set of numbers
-# Sum a set of numbers
+Find their mean,median and standard deviation
-# Find their mean,median and standard deviation
 |-
@@ Line 258: / Line 257: @@
 |-
 |09:28
-|1.Find the total goals for each player
+|Find the total goals for each player
 |-
 |09:33
-| 2.Mean of home and away goals
+|Mean of home and away goals
 |-
 |09:37
-|3.Standard deviation of home and away goals
+|Standard deviation of home and away goals
 |-
@@ Line 290: / Line 289: @@
 |-
 |10:07
-|1. Do the standard statistical operations sum , mean median and standard deviation in Python.
+| Do the standard statistical operations sum , mean median and standard deviation in Python.
 |-
 |10:14
-|2. Combine text loading and the statistical operation to solve real world problems.
+|Combine text loading and the statistical operation to solve real world problems.
 |-
@@ Line 302: / Line 301: @@
 |-
 |10:27
-|1.  Given a two dimensional list, two_dimensional_list is equal to within square brackets [3,5,8,2,1],within another square brackets [4,3,6,2,1] how do we calculate the mean of each row?
+|Given a two dimensional list, two_dimensional_list is equal to within square brackets [3,5,8,2,1],within another square brackets [4,3,6,2,1] how do we calculate the mean of each row?
 |-
 |10:49
-| 2. Calculate the median of the given list? student_marks is equal to within square brackets 74,78,56,87,91,82
+| Calculate the median of the given list? student_marks is equal to within square brackets 74,78,56,87,91,82
 |-
@@ Line 318: / Line 317: @@
 |-
 |11:20
-|1. To get the mean of each row, we just pass 1 as the second parameter to the function <tt>mean</tt>.
+|To get the mean of each row, we just pass 1 as the second parameter to the function <tt>mean</tt>.
 |-
@@ Line 326: / Line 325: @@
 |-
 |11:37
-|2. We use the function  median to calculate the median of the list
+| We use the function  median to calculate the median of the list
 |-

@@ Line 46: / Line 46: @@
 |-
 |1:02
-| We can see the content of file by double clicking on it.
+| We can see the content of the file by double clicking on it.
 |-
@@ Line 62: / Line 62: @@
 |-
 | 1:18
-| So type cat space slash home slash fossee slash sslc2 dot txt. Hit enter.
+| So type cat space slash home slash fossee slash sslc2 dot txt and Hit enter.
 |-
@@ Line 103: / Line 103: @@
 |-
 |3:57
-|Now we have an error.
+|Now we got an error.
 |-
@@ Line 151: / Line 151: @@
 |-
 |  5:19
-| Now to sum this we can say totalmarks is equal to sum within brackets L within square brackets 0 comma colon. Hit Enter.Then totalmarks. Then again Enter.
+| Now to sum this we can say total marks is equal to sum within brackets L within square brackets 0 comma colon and Hit Enter.Then total marks. Then again Enter.
 |-
 |  5:47
-| Now to get the mean we can divide the totalmarks by the length.
+| Now to get the mean we can divide the total marks by the length.
 |-
 |5:52
-|So type totalmarks slash len within brackets L in square brackets 0 comma colon.
+|So type total marks slash len within brackets L in square brackets 0 comma colon.
 |-
@@ Line 171: / Line 171: @@
 |-
 |6:31
-| But we have such a large data set and calculating the mean for each student one by one is impossible.
+| But we have such a large data set and calculating the mean of each student one by one is impossible.
 |-
@@ Line 223: / Line 223: @@
 |-
 |  7:53
-| To get the median we will simply use the function <tt>median</tt>.
+| To get the median we will simply use the function median.
 |-
@@ Line 239: / Line 239: @@
 |-
 |  8:35
-| Similarly to calculate standard deviation for English we will use the function <tt>std</tt>
+| Similarly to calculate standard deviation for English we will use the function std
 |-

@@ Line 303: / Line 303: @@
 |-
 |10:27
-|1. <nowiki>Given a two dimensional list, two_dimensional_list is equal to within square brackets [3,5,8,2,1],within another square brackets [4,3,6,2,1] how do we calculate the mean of each row?</nowiki>
+|1.  Given a two dimensional list, two_dimensional_list is equal to within square brackets [3,5,8,2,1],within another square brackets [4,3,6,2,1] how do we calculate the mean of each row?
 |-
 |10:49
-| 2.<nowiki>Calculate the median of the given list? student_marks is equal to within square brackets 74,78,56,87,91,82</nowiki>
+| 2. Calculate the median of the given list? student_marks is equal to within square brackets 74,78,56,87,91,82
 |-
@@ Line 329: / Line 329: @@
 |-
 |11:37
-|2. We use the function <tt>median</tt> to calculate the median of the list
+|2. We use the function  median to calculate the median of the list
 |-