--- a/plotting-files.txt	Mon Apr 05 22:34:25 2010 +0530
+++ b/plotting-files.txt	Tue Apr 06 16:48:23 2010 +0530
@@ -1,115 +1,83 @@
-Hello, this is second tutorial from the series of Python for 
-Scientific computing.
-
-Here we will teach you how to plot experimental data, with two
-variables. Please make sure you have pendulum.txt file, we will
-be using it for introduction of concepts(requirements page!).
-
-We shall look at inputting experimental data and plotting it. 
+**********************************************************************************
+Hello and welcome, this is the second tutorial in the series of spoken tutorials on Python for Scientific computing. 
 
-The data could be input either as lists or read from plain text/
-binary files
+Here we will teach you how to plot experimental data, with two variables.  
 
-# 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
+You could input the data either as a list or read from a plain text/binary file. 
 
-Let's begin with inputting the data as lists and plotting it. 
-
+# Before going through this video, you should have a working knowledge of
+#   - Lists
+#   - How to initialize them
+#   - How to append elements to the lists
+#   - ??? for command
+#   - How to iterate over a list
+#   - How to split a command
+#   - The plot command
+#   - How to plot two variables
+ 
+So let's begin.  First we will input the data as lists and then we will plot it. 
+So on the Terminal window type
 x = [0, 1, 2.1, 3.1, 4.2, 5.2]
-here x is a list. In python list is a container that holds number of
-objects. Various functions related to lists will be covered in more 
-detail later.
+here x is a list. In python, list is a container that holds a number of objects. Various functions related to lists will be covered in more detail later. 
 
-We create one more list to represent corresponding Y values
+Now for the corresponding Y values type
 y = [0, 0.8, 0.9, 0, -0.9, -0.8]
-
-Now we have x and y in two lists and we make a plot of x vs. y. 
+ 
+Now we have x and y in two separate lists and we plot x vs. y.
 plot (x, y, 'o')
-Here, we have our plot!
 
-[We close the plot window. ]
+Here, 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. 
+Now, that we know how to plot data from lists, we will look at plotting data from 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 before. 
 
-As an example we will use the data collected from a simple pendulum
-experiment. 
+As an example we will use the data collected from a simple pendulum experiment. Please make sure you have pendulum.txt file, as mentioned on requirement page(link)
 
 In []: cat pendulum.txt (windows?)
-
-The cat command, shows the contents of the file. 
+The cat command shows the file content.
+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.
 
-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. 
-
+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'):
-
-':' in end of for statement marks the start of block.
+ 
+Now we open the file and read it line by line.
+for line in open('pendulum.txt'): 
 
-open returns a iterable object which we traverse using for loop. In 
-python for iterates over items of any sequence.
-#we will cover more of 'for' loop in later sections
-line is a string variable storing one line at a time as for loop 
-iterates through file.
+The ':' at the end of the 'for' statement marks the start of the block.
+'open' returns an iterable object which we traverse using the 'for' loop. In  python, 'for' iterates over items of any sequence.
+#we will cover more about the 'for' loop in other spoken tutorials
+'line' is a string variable storing one line at a time as the 'for' loop iterates through the file.
 
 We split each line at the space using
-
-    point = line.split()
-
-split function will return list. In this case it will have two 
-elements, first is length and second being time.
+     point = line.split() 
+split function will return a list. In this case it will have two elements, first is length and second is time. 
 
-mind the indentation here. Everything inside 'for' loop has to be 
-indented by 4 spaces.
-
-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
+Note the indentation here. Everything inside the 'for' loop has to be indented by 4 spaces.
+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]))
-append is function to append one element to the list.
+append is a function used to append one element to the list.
     t.append(float(point[1]))
 
-By this time we have time and length values in two lists. Now to get
-square of time values we will write one more for loop which this time
-iterate through list 't'
+By now we have the time and length values in two lists. Now to get the square of the time values, we will write one more 'for' loop which will iterate through list 't'
 
 for time in t:
-    tsq.append(time*time)
+    tsq.append(time*time) 
 
-# We also calculate the squares of the time-period and append to the 
-# end of the tsq list. 
+# We also calculate the squares of the time-period and append to the
+# end of the tsq list.
 #     tsq.append(t[-1]*t[-1])
-# For any given list to access last element python provides '-1' 
+# For any given list to access the last element python provides '-1'
 # index, so we use t[-1].
 
-Now lists l(en) and tsq have the required data. We can simply plot 
-them, as we did already.
-
+Now lists l(en) and tsq have the required data. We can simply plot them, as we did earlier. 
 plot(l, tsq, 'o')
 
-Enjoy(Thank you)!
+So here is the required plot. In this way, you can plot data from files.  Hope this information was helpful. See you. 
+
+******************
 
-For alternate ways of loading data from files go through tutorial on 
-loadtxt
-******************
-We should have two tutorials here, one should be basic, using for 
-loops and lists
+For alternate ways of loading data from files go through the tutorial on loadtxt
+We should have two tutorials here, one should be basic, using for loops and lists
 Second one using loadtxt.