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! |
