Python/C2/Embellishing-a-plot/English-timed

Timing	Narration
0:00	Welcome to the tutorial on "Embellishing a Plot".
0:06	At the end of this tutorial, you will be able to, Modify the attributes of the plot -- color, line style,linewidth. Add a title to the plot with embedded LaTeX. Label x and y axes. Add annotations to the plot. Set and Get the limits of axes.
0:27	So, Before beginning this tutorial,we would suggest you to complete the tutorial on "Using plot interactively".
0:34	so,let us start ipython with pylab loaded, open the terminal and type ipython hyphen pylab.
0:48	We shall first make a simple plot and start decorating it.
0:54	So type x is equal to linspace within brackets -2,4,20
1:06	then type plot(x,sin(x))
1:15	As we can see, the default colour and the default thickness of the line is as decided by pylab.
1:23	Wouldn't it be nice if we could control these parameters in the plot?
1:28	This is possible by passing additional arguments to the plot command.
1:33	We shall first clear the figure and plot the same by passing the additional color argument.
1:39	Pass the argument 'r' for red color.
1:44	So type clf, then plot within brackets x,sin(x),within single quotes r.
2:13	The same plot is seen in red color.
2:16	The thickness of the line can be altered by 'linewidth' argument.
2:20	So type plot within brackets x,cos(x),linewidth is equal to 2
2:34	Now, a plot with line thickness 2 is produced.
2:40	Pause the video and do this exercise and then resume the video.
2:45	Plot sin(x) in blue color along with linewidth as 3.
2:53	So, now switch to terminal for solution A combination of color and linewidth would do the job for us.
3:01	So , type clf , then type plot within brackets x, sin(x),within single quotes b,linewidth is equal to 3.
3:16	To get the style of line as bunch of points not joined, pass the linestyle argument with or without color argument.
3:25	So for that type on the terminal clf, then type plot x,sin(x),within single quotes dot.
3:43	We get a plot with only points.
3:49	To get the same plot in blue color type clf, then type plot within brackets x, sin(x),within single quotes b dot.
4:02	Other available options for passing arguments can be seen in the documentation of plot.
4:07	For that , you can type in the terminal plot then question mark.
4:19	So, you can actually go through the documentation.
4:23	So , you pause the video and do this exercise and then resume the video.
4:28	Plot the sine curve with green filled circles.
4:33	so ,for solutionNow, switch to terminal . We use a combination of linestyle and color.
4:40	So ,type clf() then type plot within brackets x,cos(x), within single quotes go.
4:56	So, Pause the video here, try out the following exercise and resume the video.
5:02	Plot the curve of x versus tan(x) in red dash line and linewidth 3.
5:13	So for solution, we will switch to terminal .
5:18	Here we shall use a combination of linewidth argument and linestyle.
5:22	So in terminal you can type clf() then plot within brackets x, cos(x), within single quotes r hyphen hyphen
5:36	Now that we know how to produce a bare minimum plot with color, style and thickness of our interest, we shall look at further decorating the plot.
5:46	Let us start with a plot for the function minus x squared plus 4x minus 5.
5:52	So for that you have to type clf then plot within brackets x,minus x star x plus 4 star x minus 5,'r',linewidth is equal to 2.
6:16	As you can see, the figure does not have any description describing the plot.
6:21	To add a title to the plot to describe what the plot is,use the title command.
6:26	So, we can type in the terminal title within brackets and double quotes Parabolic function - x squared plus 4x minus 5
6:42	The figure now has a title.
6:45	But it is not formatted and does not look clean.
6:49	It would look shabby if there were fractions and more complex functions like log and exp.
6:57	So, Wouldn't it be good if the title is seen in LaTeX like formatting?
7:03	This is possible by adding a $ sign before and after the part of the string that should be in LaTeX style.
7:10	So in the command you can type title within brackets and double quotes Parabolic function dollar sign minus x squared plus 4x minus 5 dollar sign
7:26	As we can see, the polynomial is now formatted.
7:30	Pause the video here, try out the following exercise and resume the video.
7:35	Change the title of the figure such that the whole title is formatted in LaTeX style.
7:41	Switch to terminal for solution.
7:45	The solution is to enclose the whole string in between $.
7:51	So you can type title within brackets dollar sign Parabolic function -x squared plus 4x minus 5 dollar sign.
8:01	Although we have title, the plot is not complete without labelling x and y axes.
8:05	we shall label x-axis to "x" and y-axis to "f(x)".
8:12	So for that you can type in terminal xlabel within brackets in double quotes x , then in terminal ylabel within brackets in double quotes f of x.
8:31	As you can see, xlabel and 'ylabel' command takes a string as an argument.
8:37	xlabel sets the label to x-axis as 'x' and ylabel sets the name to the y-axis as 'f(x)'.
8:50	Pause the video here, try out the following exercise and resume the video.
8:57	Set the x and y labels as "x" and "f(x)" in LaTeX style.
9:04	Since we need LaTeX style formatting, all we have to do is enclose the string in between two $.
9:10	Switch to terminal for solution and type xlabel within brackets dollar sign x dollar sign. ylabel within brackets and double quotes dollar sign f of x dollar sign.
9:31	The plot is now almost complete except that the points are not named.
9:37	For example the point (2, -1) is the local maxima.
9:42	We would like to name the point accordingly.
9:47	To do this use the function annotate.
9:49	So for that you can type in the terminal annotate within brackets in double quotes local maxima comma xy is equal to within brackets 2 comma -1.
10:04	As you can see, the first argument to annotate command is the name we would like to mark the point as, and the second argument is the co-ordinates of the point at which the name should appear.
10:18	It is a tuple containing two numbers.
10:20	The first is x co-ordinate and second is y co-ordinate.
10:25	Pause the video, do this exercise and then resume the video.
10:30	Make an annotation called "root" at the point (-4, 0).
10:38	What happens to the first annotation ?
10:43	Switch to the terminal for the solution.
10:46	As we can see, every annotate command makes a new annotation on the figure.
10:52	Now we have everything we need to decorate a plot, but the plot would be incomplete if we can not set the limits of axes.
11:01	This can be done using the button provided on the plot window.
11:06	Else limits also can be get and set from the terminal.
11:13	Use "xlim()" and "ylim()" functions to get the limits.
11:17	So type in the terminal annotate within brackets in double quotes root comma xy is equal to within brackets minus 4 comma 0.
11:32	xlim function returns the current x axis limits and ylim function returns the current y-axis limits.
11:41	Set the limits of x-axis from -4 to 5 by giving command xlim(-4,5).
12:12	Similarly set the limits of y-axis appropriately.
12:22	Pause the video, do this exercise and then resume the video.
12:27	Set the limits of axes such that the area of interest is the rectangle (-1, -15) and (3, 0)
12:37	Switch to the terminal for the solution.
12:40	As we can see, the lower and upper limits of x-axis in the exercise are -1 and 3 respectively.
12:46	The lower and upper limits of y-axis are -15 and 0 respectively.
12:51	So in the command we can type xlim within brackets -1 comma 3 and ylim within brackets -15 comma 0.
13:02	This gives us the required rectangle.
13:09	This brings us to the end of this tutorial.In this tutorial,we have learnt to,Modify the attributes of plot like color, line width, line style by passing additional arguments.
13:20	Add title to a plot using 'title' command.
13:24	Incorporate LaTeX style formatting by adding a $ sign before and after the part of the string.
13:30	Label x and y axes using xlabel() and ylabel() commands.
13:36	Then, add annotations to a plot using annotate() command.
13:38	Get and set the limits of axes using xlim() and ylim() commands.
13:46	Here are some self assessment questions for you to solve.
13:50	1. Draw a plot of cosine graph between -2pi to 2pi with line thickness 4.
13:57	2. Read through the documentation and find out, is there a way to modify the alignment of text in the command ylabel.
14:05	Yes or No are the options.
14:07	And the final question. How do you set the title as x^2-5x+6 in LaTex style formatting.
14:15	Now, the answers,
14:20	1. In order to plot a cosine graph between the points -2pi and 2pi with line thickness 3,we use the linspace and plot command as, x = linspace(-2*pi, 2*pi)
14:41	then plot(x, cos(x), linewidth=4)
14:46	And the second answer is No. We do not have an option to modify the alignment of text in the command ylabel.
14:53	Then the third and final one. To set the title in LaTex style formatting,we write the equation between two dollar signs as, title("$x^2-5x+6$")
15:11	Hope you have enjoyed this tutorial and found it useful.

Contributors and Content Editors

Gaurav, Kavita salve, Minal, PoojaMoolya, Sandhya.np14, Sneha