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diff --git a/loading_data_from_files/script.rst b/loading_data_from_files/script.rst index 029983d..0ff85c0 100644 --- a/loading_data_from_files/script.rst +++ b/loading_data_from_files/script.rst @@ -14,7 +14,6 @@ .. 1. getting started with ``ipython`` -.. #[Anand: author and internal reviewer not mentioned] .. Author : Puneeth Changanti Internal Reviewer : Nishanth Amuluru External Reviewer : @@ -24,131 +23,165 @@ Script ------ +.. L1 + {{{ Show the first slide containing title, name of the production team along with the logo of MHRD }}} +.. R1 + Hello Friends. Welcome to this tutorial on "loading data from files". +.. L2 + {{{ Show slide with objectives }}} -We often require to plot points obtained from experimental -observations. +.. R2 At the end of this tutorial, you will be able to, - 1. Read data from files, containing a single column of data using the ``loadtxt`` command. + 1. Read data from files, containing a single column of data #. Read multiple columns of data, separated by spaces or other delimiters. -{{{ switch to the terminal }}} +.. L3 -As usual, let us start IPython, using +{{{ switch to the terminal }}} :: - ipython -pylab + ipython -pylab + +.. R3 + +As usual, let us switch to the terminal and start IPython, using ipython -pylab + +.. R4 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. +a list of prime numbers listed in a column, using the loadtxt command. +Please make sure that you provide the correct path of the file 'primes.txt'. The file, in our case, is present in ``/home/fossee/primes.txt``. +.. L4 + {{{ Navigate to the path in the OS, open the file and show it }}} -.. #[punch: do we need a slide for showing the path?] +.. L5 +:: -.. We use the ``cat`` command to see the contents of this file. + cat /home/fossee/primes.txt -.. #[punch: should we show the cat command here? seems like a good place - to do it] :: +.. R5 - cat /home/fossee/primes.txt +Otherwise we can use the ``cat`` command to locate the file and read the contents of it. -.. #[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? +.. R6 Now let us read this list into the variable ``primes``. + +.. L6 :: - primes = loadtxt('/home/fossee/primes.txt') + primes = loadtxt('/home/fossee/primes.txt') + +.. R7 -``primes`` is now a sequence of primes, that was listed in the file, +``primes`` is now a sequence of prime numbers, 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. +.. L7 +:: -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. Note that ``loadtxt`` needs both the columns to have -equal number of rows. + print primes + +.. R8 + +We observe that all the numbers end with a period. This is so, +because these numbers are actually read as ``floats``. + +.. L8 + +{{{Highlight the output on the terminal}}} -.. Following is an exercise that you must do. +.. R9 -.. %%1%% Use the ``cat`` command to view the contents of this file. +Now, let us use the ``loadtxt`` command to read a file ``pendulum.txt`` that contains +two columns of data. This file contains the length +of the pendulum in the first column and the corresponding time period +in the second. Note that here ``loadtxt`` needs both the columns to have +equal number of rows. -.. Please, pause the video here. Do the exercise and then continue. +We use the ``cat`` command to view the contents of this file. -.. This is how we look at the contents of the file, ``pendulum.txt`` -.. :: +.. L9 +:: -.. cat /home/fossee/pendulum.txt + cat /home/fossee/pendulum.txt -.. #[Nishanth]: The first column is L values and second is T values - from a simple pendulum experiment. - Since you are using the variable names later in the - script. - Not necessary but can be included also. +.. R10 Let us, now, read the data into the variable ``pend``. Again, it is assumed that the file is in ``/home/fossee/`` + +.. L10 :: - pend = loadtxt('/home/fossee/pendulum.txt') + pend = loadtxt('/home/fossee/pendulum.txt') + +.. R11 Let us now print the variable ``pend`` and see what's in it. + +.. L11 :: - print pend + print pend + +.. R12 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. + +.. L12 :: - L, T = loadtxt('/home/fossee/pendulum.txt', unpack=True) + 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 +.. R13 Let us now, print the variables L and T, to see what they contain. + +.. L13 + :: - print L - print T + print L + print T -.. #[Nishanth]: Stress on ``unpack=True`` ?? +.. R14 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 into two separate sequences instead of one complex sequence. -{{{ show the slide with loadtxt --- other features }}} +.. L14 + +.. R15 + +Till now, we have learnt the basic use of the ``loadtxt`` +command.Let us try an example. -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. Let us look at an example, but before that do this -exercise. +Pause the video here, try out the following exercise and resume the video. -%%1%% Read the file ``pendulum_semicolon.txt`` which contains the same +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. -Please, pause the video here. Do the exercise and then continue. +.. L15 {{{ switch back to the terminal }}} :: @@ -159,20 +192,63 @@ Please, pause the video here. Do the exercise and then continue. print T -This brings us to the end of this tutorial. +.. L16 {{{ show the summary slide }}} -You should now be able to do the following, comfortably. +.. R16 + +This brings us to the end of this tutorial. +let's revise quickly what we have learnt today.In this tutorial we learnt, - + Read data from files, containing a single column of data using the + 1. To 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. + #. To Read multiple columns of data, separated by spaces or other delimiters. + +.. L17 + +{{Show self assessment questions slide}} + +.. R17 + +1. ``loadtxt`` can read data only from a file with one column + only. True or False? + +2. Given a file ``data.txt`` with three columns of data separated by + spaces, read it into 3 separate simple sequences. + +3. Given a file ``data.txt`` with three columns of data separated by + ":", read it into 3 separate simple sequences. + + +.. L18 + +{{{solution of self assessment questions on slide}}} + +.. R18 + +And the answers, + +1. False. ``loadtxt`` command can read data from files having both single columns as well as + multiple columns. + +2. A file with three columns of data seperated by spaces to be read into 3 seperate sequences, + we use the loadtxt command as, +:: + + x = loadtxt("data.txt", unpack=True) + +3. If a file with three columns of data seperated by delimiters,we read it into three seperate sequences + by using an additional argument of delimiter in the loadtxt command +:: + + x = loadtxt("data.txt", unpack=True, delimiter=":") + +.. L19 -{{{ Show the "sponsored by FOSSEE" slide }}} +{{{ Show the Thankyou slide }}} -This tutorial was created as a part of FOSSEE project, NME ICT, MHRD India +.. R19 Hope you have enjoyed and found it useful. Thank you! |