《Learn python the hard way》Exercise 48: Advanced User Input

這幾天有點時間，想學點Python基礎，今天看到了《learn python the hard way》的 Ex48，這篇文章主要記錄一些工具的安裝，以及scan 函式的實現。

首先與Ex48相關的章節有前面的Ex46, Ex47，故我們需要先安裝一些工具，主要是一些包管理和測試框架的軟體：

Install the following Python packages:

pip from http://pypi.python.org/pypi/pip
distribute from http://pypi.python.org/pypi/distribute
nose from http://pypi.python.org/pypi/nose/
virtualenv from http://pypi.python.org/pypi/virtualenv

實際上對於Linux使用者來說安裝比較簡單，首先安裝 sudo apt-get install python-pip，接下去的3個都可以使用pip 來安裝，即

pip install distribute/nose/virtualenv

模仿Ex46 的描述，新建工程目錄為ex48，進而建立以下目錄和檔案：

setup.py 如下，一些引數可以設定成自己想要的，如NAME 更改為需要測試的模組名：

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try:
    from setuptools import setup
except ImportError:
    from distutils.core import setup

config = {
    'description': 'My Project',
    'author': 'My Name',
    'url': 'URL to get it at.',
    'download_url': 'Where to download it.',
    'author_email': 'My email.',
    'version': '0.1',
    'install_requires': ['nose'],
    'packages': ['NAME'],
    'scripts': [],
    'name': 'projectname'
}

setup(**config)

在ex48 和 tests 目錄下各touch新建一個__init__.py 檔案。

測試檔案 tests/lexicon_tests.py 摘自網站：

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from nose.tools import *
from ex48 import lexicon

def test_directions():
    assert_equal(lexicon.scan("north"), [('direction', 'north')])
    result = lexicon.scan("north south east")
    assert_equal(result, [('direction', 'north'),
                          ('direction', 'south'),
                          ('direction', 'east')])

def test_verbs():
    assert_equal(lexicon.scan("go"), [('verb', 'go')])
    result = lexicon.scan("go kill eat")
    assert_equal(result, [('verb', 'go'),
                          ('verb', 'kill'),
                          ('verb', 'eat')])

def test_stops():
    assert_equal(lexicon.scan("the"), [('stop', 'the')])
    result = lexicon.scan("the in of")
    assert_equal(result, [('stop', 'the'),
                          ('stop', 'in'),
                          ('stop', 'of')])

def test_nouns():
    assert_equal(lexicon.scan("bear"), [('noun', 'bear')])
    result = lexicon.scan("bear princess")
    assert_equal(result, [('noun', 'bear'),
                          ('noun', 'princess')])

def test_numbers():
    assert_equal(lexicon.scan("1234"), [('number', 1234)])
    result = lexicon.scan("3 91234")
    assert_equal(result, [('number', 3),
                          ('number', 91234)])

def test_errors():
    assert_equal(lexicon.scan("ASDFADFASDF"), [('error', 'ASDFADFASDF')])
    result = lexicon.scan("bear IAS princess")
    assert_equal(result, [('noun', 'bear'),
                          ('error', 'IAS'),
                          ('noun', 'princess')])

上面程式中 from ex48 import lexicon 表示從ex48 中匯入lexicon 模組，即現在我們要在ex48 目錄下寫一個lexicon.py 檔案，檔案主要是scan 函式的實現，根據網站的提示，自己實現如下：

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#!/usr/bin/env python
#coding=utf-8

import re

def convert_number(s):
    try:
        return int(s)
    except ValueError:
        return None

def scan(input_str):

    words = input_str.split(' ')

    pattern = re.compile(r'\d+')


    direction_list = ['north', 'south', 'west', 'east', 'down', 'up', 'left', 'right', 'back']
    verb_list = ['go', 'kill', 'stop', 'eat']
    stop_list = ['the', 'in', 'of', 'from', 'at', 'it']
    noun_list = ['door', 'bear', 'princess', 'cabinet']
    sentence_list = []

    for word in words:

        bool = pattern.match(word)
        if bool:
            sentence = ('number', convert_number(word))
            sentence_list.append(sentence)

        elif word in direction_list:
            sentence = ('direction', word)
            sentence_list.append(sentence)


        elif word in verb_list:
            sentence = ('verb', word)
            sentence_list.append(sentence)

        elif word in stop_list:
            sentence = ('stop', word)
            sentence_list.append(sentence)

        elif word in noun_list:
            sentence = ('noun', word)
            sentence_list.append(sentence)

        else:
            sentence = ('error', word)
            sentence_list.append(sentence)

    return sentence_list

程式中使用正規表示式來匹配數字字串，請google re 模組之。

執行測試命令，即使用lexicon_tests.py 去測試lexicon.py 裡面的函式，輸出如下：

simba@ubuntu:~/Documents/code/python/projects/ex48$ nosetests
.........
----------------------------------------------------------------------
Ran 6 tests in 0.007s

OK

參考：http://learnpythonthehardway.org/book/ex48.html

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後記：

如果在使用pip or easy_install 時提示url不正確，可以臨時修改或者修改配置檔案中的index-url為國內映象點。

下載完成，編譯安裝過程中如果提示不存在python.h，可以 sudo apt-get install python-dev or yum install python-devel

《Learn python the hard way》Exercise 48: Advanced User Input

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