100 amateur language processing knocks: 15

It is a challenge record of Language processing 100 knock 2015. The environment is Ubuntu 16.04 LTS + Python 3.5.2 : : Anaconda 4.1.1 (64-bit). Click here for a list of past knocks (http://qiita.com/segavvy/items/fb50ba8097d59475f760).

Chapter 2: UNIX Command Basics

hightemp.txt is a file that stores the record of the highest temperature in Japan in the tab-delimited format of "prefecture", "point", "℃", and "day". Create a program that performs the following processing and execute hightemp.txt as an input file. Furthermore, execute the same process with UNIX commands and check the execution result of the program.

15. Output the last N lines

Receive the natural number N by means such as command line arguments and display only the last N lines of the input. Use the tail command for confirmation.

The finished code:

main.py


# coding: utf-8

fname = 'hightemp.txt'
n = int(input('N--> '))

if n > 0:
	with open(fname) as data_file:
		lines = data_file.readlines()

	for line in lines[-n:]:
		print(line.rstrip())

Execution result:

Terminal


segavvy@ubuntu:~/document/100 language processing knock 2015/15$ python main.py 
N--> 1
Aichi Prefecture Nagoya 39.9	1942-08-02
segavvy@ubuntu:~/document/100 language processing knock 2015/15$ python main.py 
N--> 2
39 Tsuruoka, Yamagata Prefecture.9	1978-08-03
Aichi Prefecture Nagoya 39.9	1942-08-02
segavvy@ubuntu:~/document/100 language processing knock 2015/15$ python main.py 
N--> 23
40 Kumagaya, Saitama Prefecture.9	2007-08-16
40 Tajimi, Gifu Prefecture.9	2007-08-16
Yamagata 40 Yamagata.8	1933-07-25
Yamanashi Prefecture Kofu 40.7	2013-08-10
Wakayama Prefecture Katsuragi 40.6	1994-08-08
Shizuoka Prefecture Tenryu 40.6	1994-08-04
40 Katsunuma, Yamanashi Prefecture.5	2013-08-10
40 Koshigaya, Saitama Prefecture.4	2007-08-16
Gunma Prefecture Tatebayashi 40.3	2007-08-16
40 Kamisatomi, Gunma Prefecture.3	1998-07-04
Aisai 40, Aichi Prefecture.3	1994-08-05
Chiba Prefecture Ushiku 40.2	2004-07-20
40 Sakuma, Shizuoka Prefecture.2	2001-07-24
40 Uwajima, Ehime Prefecture.2	1927-07-22
40 Sakata, Yamagata Prefecture.1	1978-08-03
Gifu Prefecture Mino 40 2007-08-16
Gunma Prefecture Maebashi 40 2001-07-24
39 Mobara, Chiba.9	2013-08-11
39 Hatoyama, Saitama Prefecture.9	1997-07-05
Toyonaka 39, Osaka.9	1994-08-08
Yamanashi Prefecture Otsuki 39.9	1990-07-19
39 Tsuruoka, Yamagata Prefecture.9	1978-08-03
Aichi Prefecture Nagoya 39.9	1942-08-02
segavvy@ubuntu:~/document/100 language processing knock 2015/15$ python main.py 
N--> 24
Kochi Prefecture Ekawasaki 41 2013-08-12
40 Kumagaya, Saitama Prefecture.9	2007-08-16
40 Tajimi, Gifu Prefecture.9	2007-08-16
Yamagata 40 Yamagata.8	1933-07-25
Yamanashi Prefecture Kofu 40.7	2013-08-10
Wakayama Prefecture Katsuragi 40.6	1994-08-08
Shizuoka Prefecture Tenryu 40.6	1994-08-04
40 Katsunuma, Yamanashi Prefecture.5	2013-08-10
40 Koshigaya, Saitama Prefecture.4	2007-08-16
Gunma Prefecture Tatebayashi 40.3	2007-08-16
40 Kamisatomi, Gunma Prefecture.3	1998-07-04
Aisai 40, Aichi Prefecture.3	1994-08-05
Chiba Prefecture Ushiku 40.2	2004-07-20
40 Sakuma, Shizuoka Prefecture.2	2001-07-24
40 Uwajima, Ehime Prefecture.2	1927-07-22
40 Sakata, Yamagata Prefecture.1	1978-08-03
Gifu Prefecture Mino 40 2007-08-16
Gunma Prefecture Maebashi 40 2001-07-24
39 Mobara, Chiba.9	2013-08-11
39 Hatoyama, Saitama Prefecture.9	1997-07-05
Toyonaka 39, Osaka.9	1994-08-08
Yamanashi Prefecture Otsuki 39.9	1990-07-19
39 Tsuruoka, Yamagata Prefecture.9	1978-08-03
Aichi Prefecture Nagoya 39.9	1942-08-02

The UNIX command was confirmed by a shell script.

test.sh


#!/bin/sh

#Enter N
echo -n "N--> "
read n

#Cut out
tail --lines=$n hightemp.txt

Execution result:

Terminal


segavvy@ubuntu:~/document/100 language processing knock 2015/15$ ./test.sh
N--> 1
Aichi Prefecture Nagoya 39.9	1942-08-02
segavvy@ubuntu:~/document/100 language processing knock 2015/15$ ./test.sh
N--> 2
39 Tsuruoka, Yamagata Prefecture.9	1978-08-03
Aichi Prefecture Nagoya 39.9	1942-08-02
segavvy@ubuntu:~/document/100 language processing knock 2015/15$ ./test.sh
N--> 23
40 Kumagaya, Saitama Prefecture.9	2007-08-16
40 Tajimi, Gifu Prefecture.9	2007-08-16
Yamagata 40 Yamagata.8	1933-07-25
Yamanashi Prefecture Kofu 40.7	2013-08-10
Wakayama Prefecture Katsuragi 40.6	1994-08-08
Shizuoka Prefecture Tenryu 40.6	1994-08-04
40 Katsunuma, Yamanashi Prefecture.5	2013-08-10
40 Koshigaya, Saitama Prefecture.4	2007-08-16
Gunma Prefecture Tatebayashi 40.3	2007-08-16
40 Kamisatomi, Gunma Prefecture.3	1998-07-04
Aisai 40, Aichi Prefecture.3	1994-08-05
Chiba Prefecture Ushiku 40.2	2004-07-20
40 Sakuma, Shizuoka Prefecture.2	2001-07-24
40 Uwajima, Ehime Prefecture.2	1927-07-22
40 Sakata, Yamagata Prefecture.1	1978-08-03
Gifu Prefecture Mino 40 2007-08-16
Gunma Prefecture Maebashi 40 2001-07-24
39 Mobara, Chiba.9	2013-08-11
39 Hatoyama, Saitama Prefecture.9	1997-07-05
Toyonaka 39, Osaka.9	1994-08-08
Yamanashi Prefecture Otsuki 39.9	1990-07-19
39 Tsuruoka, Yamagata Prefecture.9	1978-08-03
Aichi Prefecture Nagoya 39.9	1942-08-02
segavvy@ubuntu:~/document/100 language processing knock 2015/15$ ./test.sh
N--> 24
Kochi Prefecture Ekawasaki 41 2013-08-12
40 Kumagaya, Saitama Prefecture.9	2007-08-16
40 Tajimi, Gifu Prefecture.9	2007-08-16
Yamagata 40 Yamagata.8	1933-07-25
Yamanashi Prefecture Kofu 40.7	2013-08-10
Wakayama Prefecture Katsuragi 40.6	1994-08-08
Shizuoka Prefecture Tenryu 40.6	1994-08-04
40 Katsunuma, Yamanashi Prefecture.5	2013-08-10
40 Koshigaya, Saitama Prefecture.4	2007-08-16
Gunma Prefecture Tatebayashi 40.3	2007-08-16
40 Kamisatomi, Gunma Prefecture.3	1998-07-04
Aisai 40, Aichi Prefecture.3	1994-08-05
Chiba Prefecture Ushiku 40.2	2004-07-20
40 Sakuma, Shizuoka Prefecture.2	2001-07-24
40 Uwajima, Ehime Prefecture.2	1927-07-22
40 Sakata, Yamagata Prefecture.1	1978-08-03
Gifu Prefecture Mino 40 2007-08-16
Gunma Prefecture Maebashi 40 2001-07-24
39 Mobara, Chiba.9	2013-08-11
39 Hatoyama, Saitama Prefecture.9	1997-07-05
Toyonaka 39, Osaka.9	1994-08-08
Yamanashi Prefecture Otsuki 39.9	1990-07-19
39 Tsuruoka, Yamagata Prefecture.9	1978-08-03
Aichi Prefecture Nagoya 39.9	1942-08-02

The result was the same.

In addition, I checked ʻif n> 0because I noticed that when 0 was entered, the slice specification becamelines [0:]` and all lines became successful. .. However, in this knock, I think that the input outside the range is not intended to be asked, and it may have been better to ignore it rather than putting it halfway.   That's all for the 16th knock. If you have any mistakes, I would appreciate it if you could point them out.

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