Difference between revisions of "Python/C2/loading-data-from-files/English-timed"
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{| border=1 | {| border=1 | ||
| − | + | |'''Time''' | |
| − | + | |'''Narration''' | |
| + | |||
|- | |- | ||
| − | | | + | | 00:01 |
| Hello Friends and Welcome to this tutorial on "loading data from files". | | Hello Friends and Welcome to this tutorial on "loading data from files". | ||
|- | |- | ||
| − | | | + | | 00:06 |
| − | | At the end of this tutorial, you will be able to, | + | | At the end of this tutorial, you will be able to, Read data from files, containing a single column of data |
| − | + | Read multiple columns of data, separated by spaces or other delimiters. | |
| − | + | ||
|- | |- | ||
| − | | | + | | 00:19 |
| Let us switch to the terminal and start IPython, using ipython hypen pylab | | Let us switch to the terminal and start IPython, using ipython hypen pylab | ||
|- | |- | ||
| − | | | + | |00:33 |
| Now, Let us begin with reading the file primes.txt, which contains a list of prime numbers listed in a column, using the loadtxt command. | | Now, Let us begin with reading the file primes.txt, which contains a list of prime numbers listed in a column, using the loadtxt command. | ||
|- | |- | ||
| − | | | + | | 00:45 |
|Please make sure that you provide the correct path of the file, 'primes.txt'. | |Please make sure that you provide the correct path of the file, 'primes.txt'. | ||
|- | |- | ||
| − | | | + | | 00:50 |
| − | |The file, in our case, is | + | |The file, in our case, is presented in slash home slash fossee slash primes.txt. |
|- | |- | ||
| − | | | + | | 00:59 |
| Otherwise we can use the cat command to locate the file and read the contents of it. | | Otherwise we can use the cat command to locate the file and read the contents of it. | ||
|- | |- | ||
| − | | | + | |01:05 |
|So type cat slash home slash fossee slash primes.txt | |So type cat slash home slash fossee slash primes.txt | ||
|- | |- | ||
| − | | | + | | 01:15 |
| Now let us read this list into the variable primes. | | Now let us read this list into the variable primes. | ||
|- | |- | ||
| − | | | + | |01:20 |
|So type primes = loadtxt within bracket in single quotes slash home slash fossee slash primes.txt | |So type primes = loadtxt within bracket in single quotes slash home slash fossee slash primes.txt | ||
|- | |- | ||
| − | | | + | | 01:41 |
|primes is now a sequence of prime numbers, that was listed in the file,``primes.txt``. | |primes is now a sequence of prime numbers, that was listed in the file,``primes.txt``. | ||
|- | |- | ||
| − | | | + | | 01:49 |
| − | |We now type,print | + | |We now type primes,print primes to see the sequence printed so type print space primes. |
|- | |- | ||
| − | | | + | | 02:00 |
| We observe that all the numbers end with a period. | | We observe that all the numbers end with a period. | ||
|- | |- | ||
| − | | | + | | 02:04 |
|This is so, because these numbers are actually read as floats | |This is so, because these numbers are actually read as floats | ||
|- | |- | ||
| − | | | + | | 02:10 |
| Now, let us use the loadtxt command to read a file pendulum.txt that contains two columns of data. | | Now, let us use the loadtxt command to read a file pendulum.txt that contains two columns of data. | ||
|- | |- | ||
| − | | | + | | 02:19 |
| This file contains the length of the pendulum in the first column and the corresponding time period in the second. | | This file contains the length of the pendulum in the first column and the corresponding time period in the second. | ||
|- | |- | ||
| − | | | + | | 02:26 |
| Note that here loadtxt needs both the columns to have equal number of rows. | | Note that here loadtxt needs both the columns to have equal number of rows. | ||
|- | |- | ||
| − | | | + | | 02:31 |
| − | |We use the cat command to view the contents of this file. | + | |We can use the cat command to view the contents of this file. |
|- | |- | ||
| − | | | + | | 02:36 |
| So type cat slash home slash fossee slash pendulum.txt | | So type cat slash home slash fossee slash pendulum.txt | ||
|- | |- | ||
| − | | | + | | 02:50 |
| Let us, now, read the data into the variable pend. | | Let us, now, read the data into the variable pend. | ||
|- | |- | ||
| − | | | + | | 02:55 |
|Again, it is assumed that the file is in slash home slash fossee | |Again, it is assumed that the file is in slash home slash fossee | ||
|- | |- | ||
| − | | | + | | 03:02 |
|So type pend = loadtxt within bracket in single quote slash home slash fossee slash pendulum.txt | |So type pend = loadtxt within bracket in single quote slash home slash fossee slash pendulum.txt | ||
|- | |- | ||
| − | | | + | | 03:21 |
| Let us now print the variable pend and see what it contains. | | Let us now print the variable pend and see what it contains. | ||
|- | |- | ||
| − | | | + | |03:26 |
|So type print pend | |So type print pend | ||
|- | |- | ||
| − | | | + | | 03:31 |
| Notice that pend is not a simple sequence like primes . | | Notice that pend is not a simple sequence like primes . | ||
|- | |- | ||
| − | | | + | | 03:35 |
|It has two sequences, containing both the columns of the data file. | |It has two sequences, containing both the columns of the data file. | ||
|- | |- | ||
| − | | | + | | 03:40 |
| − | | Let us use an additional argument of the | + | | Let us use an additional argument of the load txt command, to read it into two separate, simple sequences. |
|- | |- | ||
| − | | | + | |03:50 |
| − | |So type L, T space = space | + | |So type L, T space = space load txt within bracket single quote slash home slash fossee slash pendulum.txt comma unpack=True |
|- | |- | ||
| − | | | + | | 04:23 |
| Let us now, print the variables L and T, to see what they contain. | | Let us now, print the variables L and T, to see what they contain. | ||
|- | |- | ||
| − | | | + | |04:29 |
| − | |So type print space L | + | |So type print space L, print space T |
| − | print space T | + | |
|- | |- | ||
| − | | | + | | 04:39 |
| 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. | | 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. | ||
|- | |- | ||
| − | | | + | | 04:50 |
|unpack=True has given us the two columns into two separate sequences instead of one complex sequence. | |unpack=True has given us the two columns into two separate sequences instead of one complex sequence. | ||
|- | |- | ||
| − | | | + | | 05:00 |
| − | | Till now, we have learnt the basic use of the | + | | Till now, we have learnt the basic use of the load txt command. |
|- | |- | ||
| − | | | + | |05:05 |
| Let us try an example. | | Let us try an example. | ||
|- | |- | ||
| − | | | + | | 05:07 |
|Pause the video here, try out the following exercise and resume the video. | |Pause the video here, try out the following exercise and resume the video. | ||
|- | |- | ||
| − | | | + | | 05:12 |
|Read the file pendulum underscore semicolon.txt which contains the same data as pendulum.txt, but the columns are separated by semi-colons instead of spaces. | |Read the file pendulum underscore semicolon.txt which contains the same data as pendulum.txt, but the columns are separated by semi-colons instead of spaces. | ||
|- | |- | ||
| − | | | + | |05:27 |
| Use the IPython help to see how to do this. | | Use the IPython help to see how to do this. | ||
|- | |- | ||
| − | | | + | |05:34 |
|Switch back to the terminal | |Switch back to the terminal | ||
| − | + | L comma T = loadtxt within bracket in single quote slash home slash fossee slash pendulum underscore semicolon.txt then comma unpack=True comma delimiter=semi-colon within single quote | |
| − | L comma T = loadtxt within bracket in single quote slash home slash fossee slash pendulum underscore semicolon.txt comma unpack=True comma | + | |
| − | + | ||
|- | |- | ||
| − | | | + | |06:33 |
|Okay then type print L | |Okay then type print L | ||
|- | |- | ||
| − | | | + | |06:40 |
|print T | |print T | ||
|- | |- | ||
| − | | | + | | 06:45 |
| This brings us to the end of this tutorial. | | This brings us to the end of this tutorial. | ||
|- | |- | ||
| − | | | + | | 06:48 |
| In this tutorial, we have learnt to, | | In this tutorial, we have learnt to, | ||
|- | |- | ||
| − | | | + | | 06:51 |
| − | | 1. To 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. |
|- | |- | ||
| − | | | + | | 06:58 |
| 2. To Read multiple columns of data, separated by spaces or other delimiters. | | 2. To Read multiple columns of data, separated by spaces or other delimiters. | ||
|- | |- | ||
| − | | | + | | 07:04 |
| Here are some self assessment questions for you to solve | | Here are some self assessment questions for you to solve | ||
1. loadtxt can read data from a file with one column only. True or False? | 1. loadtxt can read data from a file with one column only. True or False? | ||
|- | |- | ||
| − | | | + | | 07:18 |
| 2. Given a file data.txt with three columns of data separated by spaces, read it into 3 separate simple sequences. | | 2. Given a file data.txt with three columns of data separated by spaces, read it into 3 separate simple sequences. | ||
|- | |- | ||
| − | | | + | | 07:29 |
| 3. Given a file data.txt with three columns of data separated by ":", 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. | ||
|- | |- | ||
| − | | | + | | 07:45 |
| − | | And the answers,1. False. | + | | And now the answers,1. False. |
|- | |- | ||
| − | | | + | | 07:50 |
|loadtxt command can read data from files having both single columns as well as multiple columns. | |loadtxt command can read data from files having both single columns as well as multiple columns. | ||
|- | |- | ||
| − | | | + | | 07:58 |
| 2. A file with three columns of data separated by spaces to be read into 3 separate sequences, we use the loadtxt command as, x = loadtxt within bracket in double quotes data.txt comma unpack=True | | 2. A file with three columns of data separated by spaces to be read into 3 separate sequences, we use the loadtxt command as, x = loadtxt within bracket in double quotes data.txt comma unpack=True | ||
|- | |- | ||
| − | | | + | | 08:19 |
| 3. If a file with three columns of data separated by delimiters,we read it into three separate sequences by using an additional argument of delimiter in the loadtxt command | | 3. If a file with three columns of data separated by delimiters,we read it into three separate sequences by using an additional argument of delimiter in the loadtxt command | ||
| − | x = loadtxt within bracket in double quotes data.txt comma unpack=True comma delimiter=in double quotes | + | x = loadtxt within bracket in double quotes data.txt comma unpack=True comma delimiter=in double quotes semicolon) |
|- | |- | ||
| − | | | + | | 08:51 |
| Hope you have enjoyed this tutorial and found it useful. | | Hope you have enjoyed this tutorial and found it useful. | ||
|- | |- | ||
| − | | | + | | 08:55 |
| Thank you! | | Thank you! | ||
Latest revision as of 10:44, 27 March 2017
| Time | Narration |
| 00:01 | Hello Friends and Welcome to this tutorial on "loading data from files". |
| 00:06 | At the end of this tutorial, you will be able to, Read data from files, containing a single column of data
Read multiple columns of data, separated by spaces or other delimiters. |
| 00:19 | Let us switch to the terminal and start IPython, using ipython hypen pylab |
| 00:33 | Now, Let us begin with reading the file primes.txt, which contains a list of prime numbers listed in a column, using the loadtxt command. |
| 00:45 | Please make sure that you provide the correct path of the file, 'primes.txt'. |
| 00:50 | The file, in our case, is presented in slash home slash fossee slash primes.txt. |
| 00:59 | Otherwise we can use the cat command to locate the file and read the contents of it. |
| 01:05 | So type cat slash home slash fossee slash primes.txt |
| 01:15 | Now let us read this list into the variable primes. |
| 01:20 | So type primes = loadtxt within bracket in single quotes slash home slash fossee slash primes.txt |
| 01:41 | primes is now a sequence of prime numbers, that was listed in the file,``primes.txt``. |
| 01:49 | We now type primes,print primes to see the sequence printed so type print space primes. |
| 02:00 | We observe that all the numbers end with a period. |
| 02:04 | This is so, because these numbers are actually read as floats |
| 02:10 | Now, let us use the loadtxt command to read a file pendulum.txt that contains two columns of data. |
| 02:19 | This file contains the length of the pendulum in the first column and the corresponding time period in the second. |
| 02:26 | Note that here loadtxt needs both the columns to have equal number of rows. |
| 02:31 | We can use the cat command to view the contents of this file. |
| 02:36 | So type cat slash home slash fossee slash pendulum.txt |
| 02:50 | Let us, now, read the data into the variable pend. |
| 02:55 | Again, it is assumed that the file is in slash home slash fossee |
| 03:02 | So type pend = loadtxt within bracket in single quote slash home slash fossee slash pendulum.txt |
| 03:21 | Let us now print the variable pend and see what it contains. |
| 03:26 | So type print pend |
| 03:31 | Notice that pend is not a simple sequence like primes . |
| 03:35 | It has two sequences, containing both the columns of the data file. |
| 03:40 | Let us use an additional argument of the load txt command, to read it into two separate, simple sequences. |
| 03:50 | So type L, T space = space load txt within bracket single quote slash home slash fossee slash pendulum.txt comma unpack=True |
| 04:23 | Let us now, print the variables L and T, to see what they contain. |
| 04:29 | So type print space L, print space T |
| 04:39 | 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. |
| 04:50 | unpack=True has given us the two columns into two separate sequences instead of one complex sequence. |
| 05:00 | Till now, we have learnt the basic use of the load txt command. |
| 05:05 | Let us try an example. |
| 05:07 | Pause the video here, try out the following exercise and resume the video. |
| 05:12 | Read the file pendulum underscore semicolon.txt which contains the same data as pendulum.txt, but the columns are separated by semi-colons instead of spaces. |
| 05:27 | Use the IPython help to see how to do this. |
| 05:34 | Switch back to the terminal
L comma T = loadtxt within bracket in single quote slash home slash fossee slash pendulum underscore semicolon.txt then comma unpack=True comma delimiter=semi-colon within single quote |
| 06:33 | Okay then type print L |
| 06:40 | print T |
| 06:45 | This brings us to the end of this tutorial. |
| 06:48 | In this tutorial, we have learnt to, |
| 06:51 | 1. To Read data from files, containing a single column of data using the loadtxt command. |
| 06:58 | 2. To Read multiple columns of data, separated by spaces or other delimiters. |
| 07:04 | Here are some self assessment questions for you to solve
1. loadtxt can read data from a file with one column only. True or False? |
| 07:18 | 2. Given a file data.txt with three columns of data separated by spaces, read it into 3 separate simple sequences. |
| 07:29 | 3. Given a file data.txt with three columns of data separated by ":", read it into 3 separate simple sequences. |
| 07:45 | And now the answers,1. False. |
| 07:50 | loadtxt command can read data from files having both single columns as well as multiple columns. |
| 07:58 | 2. A file with three columns of data separated by spaces to be read into 3 separate sequences, we use the loadtxt command as, x = loadtxt within bracket in double quotes data.txt comma unpack=True |
| 08:19 | 3. If a file with three columns of data separated by delimiters,we read it into three separate sequences by using an additional argument of delimiter in the loadtxt command
x = loadtxt within bracket in double quotes data.txt comma unpack=True comma delimiter=in double quotes semicolon) |
| 08:51 | Hope you have enjoyed this tutorial and found it useful. |
| 08:55 | Thank you! |
