View source for Python/C2/Embellishing-a-plot/English-timed

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!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.

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| 0:48
| We shall first make a simple plot and start decorating it.

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| 0:54
|So type x is equal to linspace within brackets -2,4,20

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| 1:06
|then type plot(x,sin(x))

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| 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.

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| 1:33
| We shall first clear the figure and plot the same by passing the additional color argument.

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| 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.

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|  2:13
| The same plot is seen in red color.

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| 2:16
| The thickness of the line can be altered by 'linewidth' argument.

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| 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.

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| 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.

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| 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.

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| 3:43
| We get a plot with only points.

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| 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.

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| 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.

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| 4:28
|Plot the sine curve with green filled circles.

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| 4:33
| so ,for solutionNow, switch to terminal . We use a combination of linestyle and color.

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|4:40
|So ,type clf() then type plot within brackets x,cos(x), within single quotes go.

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|4:56
|So, Pause the video here, try out the following exercise and resume the video.

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|5:02
|Plot the curve of x versus tan(x) in red dash line and linewidth 3.

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| 5:13
| So for solution, we will switch to terminal . 

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| 5:18
|Here we shall use a combination of linewidth argument and linestyle.

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|5:22
|So in terminal you can type clf() then plot within brackets x, cos(x), within single quotes r hyphen hyphen

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| 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.

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|  5:46
| Let us start with a plot for the function minus x squared plus  4x minus  5.

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|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.

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| 6:16
| As you can see, the figure does not have any description describing the plot.

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| 6:21
|To add a title to the plot to describe what the plot is,use the <tt>title</tt> command.

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|6:26
|So, we can type in the terminal title within brackets and double quotes Parabolic function - x squared plus  4x minus 5

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|6:42
|The figure now has a title.

|-
|6:45
| But it is not formatted and does not look clean.

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| 6:49
| It would look shabby if there were fractions and more complex functions like log and exp.

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| 6:57
| So, Wouldn't it be good if the title is seen in LaTeX like formatting?

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| 7:03
| This is possible by adding a <tt>$</tt> sign before and after the part of the string that should be in LaTeX style.

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|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


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| 7:26
| As we can see, the polynomial is now formatted.

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| 7:30
| Pause the video here, try out the following exercise and resume the video.

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| 7:35
| Change the title of the figure such that the whole title is formatted in LaTeX style.

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| 7:41
| Switch to terminal for solution. 

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| 7:45
| The solution is to enclose the whole string in between $.

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|7:51
|So you can type title within brackets dollar sign Parabolic function -x squared plus 4x minus 5 dollar sign.

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| 8:01
| Although we have title, the plot is not complete without labelling x and y axes. 

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| 8:05
| we shall label x-axis to "x" and y-axis to "f(x)".

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| 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.

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| 8:31
| As you can see, <tt>xlabel</tt> and 'ylabel' command takes a string as an argument. 

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| 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.

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| 8:57
| Set the x and y labels as "x" and "f(x)" in LaTeX style.

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| 9:04
| Since we need LaTeX style formatting, all we have to do is enclose the string in between two $.

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| 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.
 

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| 9:31
| The plot is now almost complete except that the points are not named.

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| 9:37
| For example the point (2, -1) is the local maxima.

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| 9:42
| We would like to name the point accordingly. 

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|9:47
|To do this use the function <tt>annotate</tt>.

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|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.

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| 10:04
| As you can see, the first argument to <tt>annotate</tt> 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.

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| 10:18
| It is a tuple containing two numbers.

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| 10:20
| The first is x co-ordinate and second is y co-ordinate.

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| 10:25
| Pause the video, do this exercise and then resume the video.

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|10:30
|Make an annotation called "root" at the point (-4, 0).

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| 10:38
| What happens to the first annotation ?

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| 10:43
| Switch to the terminal for the solution. 

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|10:46
|As we can see, every annotate command makes a new annotation on the figure.

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|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.

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|11:06
|Else limits also can be get and set from the terminal.

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| 11:13
| Use "xlim()" and "ylim()" functions to get the limits.

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|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.

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| 11:32
| <tt>xlim</tt> function returns the current x axis limits and <tt>ylim</tt> function returns the current y-axis limits.

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|11:41
|Set the limits of x-axis from -4 to 5 by giving command xlim(-4,5).

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|  12:12
| Similarly set the limits of y-axis appropriately.

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| 12:22
| Pause the video, do this exercise and then resume the video.

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|12:27
|Set the limits of axes such that the area of interest is the rectangle (-1, -15) and (3, 0)

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| 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.

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|12:46
| The lower and upper limits of y-axis are -15 and 0 respectively.

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|12:51
|So in the command we can type xlim within brackets -1 comma 3 and ylim within brackets -15 comma 0.

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| 13:02
| This gives us the required rectangle.

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| 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.

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| 13:20
|  Add title to a plot using 'title' command.

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| 13:24
|  Incorporate LaTeX style formatting by adding a <tt>$</tt> sign before and after the part of the string.

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| 13:30
|  Label x and y axes using xlabel() and ylabel() commands.

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| 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.

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| 13:50
| 1. Draw a plot of cosine graph between -2pi to 2pi with line thickness 4.

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| 13:57
| 2. Read through the documentation and find out, is there a way to modify the alignment of text in the command <tt>ylabel</tt>.

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| 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,

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| 14:20
| 1. In order to plot a cosine graph between the points -2pi and 2pi with line thickness 3,we use the <tt>linspace</tt> and <tt>plot</tt> command as, x = linspace(-2*pi, 2*pi)

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| 14:41
| then plot(x, cos(x), linewidth=4)

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| 14:46
| And the second answer is No. We do not have an option to modify the alignment of text in the command <tt>ylabel</tt>.

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|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. 



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