Python-3.4.3/C2/Subplots/English-timed
| Time | Narration |
| 00:01 | Hello friends! Welcome to the spoken tutorial on Subplots. |
| 00:06 | At the end of this tutorial, you will be able to create and switch between subplots. |
| 00:14 | To record this tutorial, I am using:
Ubuntu Linux 14.04 operating system, Python 3.4.3, IPython 5.1.0. |
| 00:29 | To practise this tutorial, you should know how to:
run basic Python commands on the ipython console, use Plots interactively, embellish a plot. If not, see the pre-requisite Python tutorials on this website. |
| 00:48 | Let us first open the Terminal by pressing Ctrl+Alt+T keys simultaneously.
Now, type ipython3 and press Enter. |
| 01:01 | Let us initialise the pylab package. Type: percentage pylab and press Enter. |
| 01:10 | To compare two plots, we draw the plots in the same plotting area. |
| 01:15 | Let us now create two plots- a cosine plot and an exponential curve in the same plotting area. |
| 01:24 | Type: x equals to linspace inside brackets 0 comma 50 comma 500 and press Enter.
plot inside the brackets x comma cos(x). |
| 01:45 | Type: y equals to linspace inside brackets 0 comma 5 comma 100.
plot inside brackets y comma y square. |
| 02:04 | Here, the two plots have different regular axes. So, we cannot draw overlaid plots. |
| 02:13 | In such cases, we can draw subplots. |
| 02:17 | We use 'subplot' command to accomplish this.
Type: clf() subplot inside the brackets 2 comma 1 comma 1. |
| 02:33 | We can see the first subplot. The subplot command takes three arguments. |
| 02:40 | The first argument is the number of rows of subplots that must be created.
Here the first argument is 2 to split the plot horizontally. |
| 02:53 | The second argument is the number of columns of subplots that must be created.
Here, the second argument is 1. So, plot will not split vertically. |
| 03:07 | The last argument specifies the serial number for the subplot.
Here, we passed 1 as the argument which creates the upper subplot. |
| 03:19 | If we execute the subplot command as-
subplot inside the brackets 2 comma 1 comma 2, the lower subplot is created. |
| 03:34 | Here, we can see now two subplots. |
| 03:38 | Now, we can draw plots in each of the subplot area using the plot command.
Type: subplot inside brackets 2 comma 1 comma 1. plot inside brackets x comma cos(x). |
| 04:00 | Now, type: subplot inside brackets 2 comma 1 comma 2
plot y comma y square |
| 04:16 | This created two plots, one in each of the subplot area. The top subplot holds a cosine curve and the bottom subplot holds a parabola. |
| 04:29 | It is clear from the two subplots that both have different regular axes. |
| 04:35 | For the cosine curve, x-axis varies from 0 to 50 and y-axis varies from minus 1 to 1. |
| 04:46 | For the parabolic curve, x-axis varies from 0 to 5 and y-axis varies from 0 to 25. |
| 04:57 | Now clear the plot window. |
| 05:00 | Pause the video. Try this exercise and then resume the video. |
| 05:05 | Pressure, Volume and Temperatures are held by the equation Pv equals to nRT where nR is a constant. |
| 05:16 | Assume nR equals to 0.01 Joules per Kelvin and T equals to 200K. V can be in the range from 21cc to 100cc. |
| 05:29 | Draw two different plots as subplots:
Pressure v/s Volume plot and Pressure v/s Temperature plot. |
| 05:39 | Switch to the terminal for the solution. |
| 05:43 | To start with, we have been given the range of Volume from which we can define the variable v. |
| 05:51 | v equals to linspace inside brackets 21 comma 100 comma 500. |
| 06:03 | We can create first subplot and draw Pressure v/s Volume graph using this v.
subplot(2 comma 1 comma 1) plot(v comma 2 point 0 by v) |
| 06:24 | We know that nRT is a constant which is equal to 2.0
since nR is equal to 0.01 Joules per Kelvin and T equals to 200 Kelvin. |
| 06:38 | Now, we can create the second subplot and draw the Pressure v/s Temperature plot as follows.
subplot(2 comma 1 comma 2) plot(200 comma 2 point 0 divided by v) |
| 07:02 | We have an error now, telling x and y dimensions don't match. |
| 07:08 | So, we will create same number of points for temperature. |
| 07:14 | Type: t equals to linspace inside brackets 200 comma 200 comma 500. |
| 07:27 | Now, we have 500 values in t and each with the value 200 Kelvin. |
| 07:35 | Plotting this data, we get the required plot.
plot inside brackets t comma 2 point 0 divided by v |
| 07:48 | We can see two subplots of Pressure v/s Volume and Pressure v/s Temperature respectively. |
| 07:56 | This brings us to the end of this tutorial.
In this tutorial, we have learnt to create subplots and to switch between them. |
| 08:08 | Here are some self assessment questions for you to solve. |
| 08:12 | 1. Which of the following is correct?
subplot inside brackets numRows comma numCols comma plotNum , subplot inside brackets numRows comma numCols , subplot inside brackets numCols comma numRows. |
| 08:36 | And the answer is first option.
1.The subplot command takes three arguments namely the number of rows, number of columns and the plot number. |
| 08:48 | Please post your timed queries in this forum. |
| 08:53 | Please post your general queries on Python in this forum. |
| 08:59 | The FOSSEE team coordinates the TBC project. |
| 09:04 | Spoken-tutorial is funded by NMEICT, MHRD, Govt. of India. For more details, visit this website. |
| 09:15 | This is Usha from IIT Bombay, signing off. Thank You. |
