Difference between revisions of "Python/C2/Plotting-the-data/English-timed"

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Latest revision as of 10:48, 27 March 2017

Time Narration
00:01 Hello Friends and Welcome to this tutorial on "Plotting Experimental data".
00:05 At the end of this tutorial, you will be able to,

Define a list of numbers. perform element wise squaring of the list. Plot data points. plot errorbars.

00:18 One needs to be familiar with the concepts of plotting mathematical functions in Python.
00:23 We will use data from a Simple Pendulum Experiment to illustrate.
00:30 As we know for a simple pendulum, length L is directly proportional to the square of time T.
00:37 We shall be plotting L and T square values.
00:40 First we will have to initiate L and T values.
00:44 We initiate them as sequence of values.
00:47 We define a sequence by comma separated values inside two square brackets.
00:52 This is also called a List.
00:54 Let's create two sequences L and t.
00:58 L = [0.1, 0.2, 0.3, 0.4, 0.5,0.6, 0.7, 0.8, 0.9]
01:10 T= [0.69, 0.90, 1.19,1.30, 1.47, 1.58, 1.77, 1.83, 1.94]
01:29 To obtain the square of sequence T we will use the function square with argument T.
01:36 This is saved into the variable Tsquare.
01:38 So type Tsquare=square withinbracket T
01:55 Tsqaure enter
02:00 Now to plot L versus T square, we will simply type
02:07 plot within bracket L comma Tsquare comma within single quote dot
02:21 Here single quote dot displays the plot in a dot pattern.
02:26 You can also specify 'o' for big dots.
02:31 For this let us clear the first plot .
02:34 Type clf closing bracket and hit enter
02:39 Then Type plot within bracket L comma Tsquare comma within single quote o hit enter now to clear the bracket type clf closing bracket
03:01 Let us move further.
03:03 For any experimental there is always an error in measurements due to instrumental and human constraints.
03:10 Now we shall try and take these errors into account in our plots .
03:17 Pause the video here, try out the following exercise and resume the video.
03:21 Plot the given experimental data with large dots.
03:25 The data is on your screen.
03:29 Its given in delta underscore delta L and delta underscore T
03:37 We shall again initialize the sequence values in the same manner as we did for L and T.
03:48 Now to plot L vs T square with an error bar we use the function errorbar() .
04:00 Before plotting the data we need to get the data of delta L and delta T
04:05 delta L= within square bracket 0.08,0.09,0.07,0.05,0.06,0.00,0.06,0.06,0.01
04:25 delta T= [0.04,0.08,0.03,0.05,0.03,0.03,0.04,0.07,0.08]
04:40 Now use the error function
04:44 Type errorbar within bracket L comma Tsquare comma xerr=delta underscore L comma yerr=delta underscore T comma fmt= in single quote bo
05:32 This gives a plot with error bar of x and y axis.
05:36 The dots are of blue color.
05:38 The parameters xerr and yerr are error on x and y axis and fmt is the format of the plot.
05:46 similarly we can draw the same error bar with small red dots just change the parameters of fmt to r dot.
05:59 Type clf() to clear the plot errorbar within bracket L comma Tsquare comma xerr=delta underscore L comma yerr=delta underscore T comma fmt=in single quote r and hit enter.
06:24 you can explore other options to errorbar using the documentation of errorbar.
06:30 errorbar? on terminal
06:38 Pause the video here, try out the following exercise and resume the video.
06:44 Plot the given experimental data with small dots and also include the error in your plot.
06:51 The data is on your screen for delta s delta n
07:00 This brings us to the end of the end of this tutorial.
07:03 In this tutorial, we have learnt to, to declare a sequence of numbers using the function array.
07:09 to perform elementwise squaring using the square function.
07:14 to use the various options available for plotting like dots,lines.
07:20 to Plot experimental data such that we can also represent error by using the errorbar() function.
07:28 Here are some self assessment questions for you to solve
07:32 Square the following sequence.br distance underscore values=within square bracket 2.1 comma 4.6 comma 8.72 comma 9.03
07:44 Plot L versus T in red pluses.
07:52 And the answers,
07:55 To square a sequence of values, we use the function square
08:02 So that we have to Type square within bracket distance underscore values
08:09 We pass an additional argument stating the desired parameter
08:14 Type plot within bracket L comma T comma within single quote r+
08:24 Hope you have enjoyed this tutorial and found it useful.
08:27 Thank You!

Contributors and Content Editors

Gaurav, Minal, PoojaMoolya, Sneha