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-* Plotting Experimental Data
-*** Outline
-***** Introduction
-******* Why do we want to do that?
-******* Inputting data
-********* Lists
-********* Files
-******* Arsenal Required
-********* Lists
-*********** initializing
-*********** appending to lists
-********* for loops
-*********** iterating over a list
-********* basic plotting
-***** Inputting data as lists
-******* Input the dependent and independent variables in two lists
-******* Plot the points
-***** Plotting from files
-******* Look at the file
-******* Read the file and get data into variables
-******* Do any massaging required
-******* Plot the points
-
-*** Script
-
-This video will teach you how to plot experimental data, with two
-variables. 
-
-In general, we don't plot (analytical) functions. We often have
-experimental data points, that we wish to plot. We shall look at
-inputting this data and plotting it. 
-
-The data could be input (or entered) in two formats. For smaller data
-sets we could use lists to input the data and use plain text files for
-(somewhat?) larger ones. (Binary files?)
-
-[[[Before starting with this video, you should be comfortable with
-  - Lists
-    - initializing them
-    - appending elements to lists
-  - for command
-    - iterating over a list
-  - split command
-  - plot command
-    - plotting two variables
-]]]
-
-Let's begin with inputting the data as lists and plotting it. 
-
-x = [0, 1, 2.1, 3.1, 4.2, 5.2]
-y = [0, 0.8, 0.9, 0, -0.9, -0.8]
-Now we have two lists x and y, with the values that we wish to plot. 
-
-We say:
-plot (x, y, 'o')
-
-and there, we have our plot!
-
-[We close the plot window. ]
-
-Now, that we know how to plot data which is in lists, we will look at
-plotting data which is in a text file. Essentially, we read the data
-from the file and massage it into lists again. Then we can easily
-plot it, as we already did. 
-
-As an example we will use the data collected from a simple pendulum
-experiment. We have the data of, the length of pendulum vs. the time
-period of the pendulum in the file pendulum.txt
-
-In []: cat pendulum.txt (windows?)
-
-The cat command, shows the contents of the file. 
-
-The first column is the length of the pendulum and the second column
-is the time. We read the file line-by-line, collect the data into
-lists and plot them. 
-
-We begin with initializing three empty lists for length, time-period
-and square of the time-period. 
-
-l = []
-t = []
-tsq = []
-
-Now we open the file and read it line by line. 
-for line in open('pendulum.txt'):
-
-We split each line at the space 
-    point = line.split()
-
-Then we append the length and time values to the corresponding
-lists. Note that they are converted from strings to floats, before
-appending to the lists
-    l.append(float(point[0])
-    t.append(float(point[1])
-We also calculate the squares of the time-period and append to the end
-of the tsq list. 
-    tsq.append(t[-1]*t[-1])
-As you might be aware, t[-1] gives the last element of the list t. 
-
-Now the lists l, t have the required data. We can simply plot them, as
-we did already. 
-
-plot(l, t, 'o')
-
-Enjoy!
-
-*** Notes
-    - Also put in code snippets?