--- a/loading-data-from-files.rst Wed Oct 06 15:08:52 2010 +0530
+++ /dev/null Thu Jan 01 00:00:00 1970 +0000
@@ -1,146 +0,0 @@
-========
- Script
-========
-
-Welcome to this tutorial on loading data from files.
-
-{{{ Screen shows welcome slide }}}
-
-We often require to plot points obtained from experimental
-observations. In this tutorial we shall learn to read data from files
-and save it into sequences that can later be used to plot.
-
-{{{ Show the outline for this tutorial }}}
-
-We shall use the ``loadtxt`` command to load data from files. We will
-be looking at how to read a file with multiple columns of data and
-load each column of data into a sequence.
-
-{{{ switch back to the terminal }}}
-
-As usual, let us start IPython, using
-::
-
- ipython -pylab
-
-Now, Let us begin with reading the file primes.txt, which contains
-just a list of primes listed in a column, using the loadtxt command.
-The file, in our case, is present in ``/home/fossee/primes.txt``.
-
-{{{ Navigate to the path in the OS, open the file and show it }}}
-
-.. #[punch: do we need a slide for showing the path?]
-
-.. We use the ``cat`` command to see the contents of this file.
-
-.. #[punch: should we show the cat command here? seems like a good place
- to do it] ::
-
- cat /home/fossee/primes.txt
-
-.. #[Nishanth]: A problem for windows users.
- Should we simply open the file and show them the data
- so that we can be fine with GNU/Linux ;) and windows?
-
-Now let us read this list into the variable ``primes``.
-::
-
- primes = loadtxt('/home/fossee/primes.txt')
-
-``primes`` is now a sequence of primes, that was listed in the file,
-``primes.txt``.
-
-We now type, ``print primes`` to see the sequence printed.
-
-We observe that all of the numbers end with a period. This is so,
-because these numbers are actually read as ``floats``. We shall learn
-about them, later.
-
-Now, let us use the ``loadtxt`` command to read a file that contains
-two columns of data, ``pendulum.txt``. This file contains the length
-of the pendulum in the first column and the corresponding time period
-in the second.
-
-%%1%% Pause the video here, and use the ``cat`` command to view the
-contents of this file and then resume the video.
-
-This is how we look at the contents of the file, ``pendulum.txt``
-::
-
- cat /home/fossee/pendulum.txt
-
-.. #[Nishanth]: The first column is L values and second is T values
- from a simle pelculum experiment.
- Since you are using the variable names later in the
- script.
- Not necessary but can be included also.
-
-Let us, now, read the data into the variable ``pend``. Again, it is
-assumed that the file is in ``/home/fossee/``
-::
-
- pend = loadtxt('/home/fossee/pendulum.txt')
-
-Let us now print the variable ``pend`` and see what's in it.
-::
-
- print pend
-
-Notice that ``pend`` is not a simple sequence like ``primes``. It has
-two sequences, containing both the columns of the data file. Let us
-use an additional argument of the ``loadtxt`` command, to read it into
-two separate, simple sequences.
-::
-
- L, T = loadtxt('/home/fossee/pendulum.txt', unpack=True)
-
-.. #[Nishanth]: It has a sequence of items in which each item contains
- two values. first is l and second is t
-
-Let us now, print the variables L and T, to see what they contain.
-::
-
- print L
- print T
-
-.. #[Nishanth]: Stress on ``unpack=True`` ??
-
-Notice, that L and T now contain the first and second columns of data
-from the data file, ``pendulum.txt``, and they are both simple
-sequences. ``unpack=True`` has given us the two columns in to two
-separate sequences instead of one complex sequence.
-
-{{{ show the slide with loadtxt --- other features }}}
-
-In this tutorial, we have learnt the basic use of the ``loadtxt``
-command, which is capable of doing a lot more than we have used it for
-until now, for example
-
-%%2%% Pause the video here, and read the file
-``pendulum_semicolon.txt`` which contains the same data as
-``pendulum.txt``, but the columns are separated by semi-colons instead
-of spaces. Use the IPython help to see how to do this. Once you have
-finished, resume the video to look at the solution.
-
-{{{ switch back to the terminal }}}
-::
-
- L, T = loadtxt('/home/fossee/pendulum_semicolon.txt', unpack=True, delimiter=';')
-
- print L
-
- print T
-
-This brings us to the end of this tutorial.
-
-{{{ show the summary slide }}}
-
-You should now be able to do the following, comfortably.
-
- + Read data from files, containing a single column of data using the
- ``loadtxt`` command.
- + Read multiple columns of data, separated by spaces or other
- delimiters.
-
-Thank you!
-