创建解析器代码

Question

我对 python 完全陌生，以前从未使用过它。我被困在这个程序上，该程序假设是一个命令行程序，它要求输入关键字，然后在可用标题列表中搜索它们。我使用json将api的信息加载到字典中并且能够搜索它。

我的主要问题是我不知道如何执行 argparser 以使其成为命令行程序。

帮助？

到目前为止，这是我所拥有的代码：

import requests
import argparse
import json
from urllib.request import urlopen


def create_json_file_from_api(url):
    request = urlopen(url)
    data = request.read().decode("utf-8")
    j_data = json.loads(data)
    return j_data


json_data = create_json_file_from_api("http://hn.algolia.com/api/v1/search_by_date?tags=story&numericFilters=created_at_i>1488196800,created_at_i<1488715200")
print(json_data) #making sure the data pulled is correct

def _build_array_of_necessary_data(data, d=[]):
    if 'hits' in data:
        for t in data['hits']:
            d.append({'title' : t.get('title'), 'points': t.get('points'), 'url' : t.get('url')})
            _build_array_of_necessary_data(t,d)
    return d

j = _build_array_of_necessary_data(json_data)
print(j) #testing the function above
def _search_titles_for_keywords(data, word, s=[]):
    for c in data:
        if word in c['title']:
            s.append({'title' : c.get('title')})
    return s

word = "the" #needs to be input by user
word.upper() == word.lower()
k = _search_titles_for_keywords(j, word)
print(k) #testing the function above

def _search_links_for_point_value(data, points, s=[]):
    points = int(points)

    for c in data:
        if points <= c['points']:
            s.append({'Title of article is' : c.get('title')})
    return s

points = "7" #needs to be input by user
l = _search_links_for_point_value(j, points)

print(l)

Answer 1

如果你想把它作为一个带参数的 python 脚本运行，你需要有

if __name__ == '__main__':
    ...

告诉python运行下面的内容。可以从命令行通过传递带有-w 或--word 标志的'word' 参数和带有-p 或--points 标志的'points' 参数来运行以下命令。例子：

C:\Users\username\Documents\> python jsonparser.py -w xerox -p 2
or
C:\Users\username\Documents\> python jsonparser.py --points 3 --word hello

这是重构后的代码：

import argparse
from sys import argv
import json
from urllib.request import urlopen


def create_json_file_from_api(url):
    request = urlopen(url)
    data = request.read().decode("utf-8")
    j_data = json.loads(data)
    return j_data

def _build_array_of_necessary_data(data, d=[]):
    if 'hits' in data:
        for t in data['hits']:
            d.append({'title' : t.get('title'), 'points': t.get('points'), 'url' : t.get('url')})
            _build_array_of_necessary_data(t,d)
    return d

def _search_titles_for_keywords(data, word, s=[]):
    for c in data:
        if word in c['title'].lower():
            s.append({'title' : c.get('title')})
    return s

def _search_links_for_point_value(data, points, s=[]):
    points = int(points)

    for c in data:
        if points <= c['points']:
            s.append({'Title of article is' : c.get('title')})
    return s


if __name__ == '__main__':
    # create an argument parser, add argument with flags
    parser = argparse.ArgumentParser(description='Search JSON data for `word` and `points`')
    parser.add_argument('-w', '--word', type=str, required=True, 
        help='The keyword to search for in the titles.')
    parser.add_argument('-p', '--points', type=int, required=True, 
        help='The points value to search for in the links.')
    # parse the argument line
    params = parser.parse_args(argv[1:])

    url = "http://hn.algolia.com/api/v1/search_by_date?tags=story&numericFilters=created_at_i%3E1488196800,created_at_i%3C1488715200"
    json_data = create_json_file_from_api(url)
    print(json_data[:200]) #making sure the data pulled is correct

    j = _build_array_of_necessary_data(json_data)
    print(j) #testing the function above

    k = _search_titles_for_keywords(j, params.word.lower())
    print(k) #testing the function above

    l = _search_links_for_point_value(j, params.points)
    print(l)

Answer 2

只需更改您设置点的行以要求用户输入

points = input("Enter points ")

然后您的程序将向用户询问积分。不过，这没有使用 argparser。当您的脚本因更多输入选项等而变得复杂时，您可以查看 argparser。 https://docs.python.org/3/library/argparse.html

Answer 3

要使用argparse，您首先需要声明ArgumentParser 对象，然后您可以使用add_argument() 方法向该对象添加参数。在此之后，您可以使用parse_args() 方法来解析命令行参数。

作为使用您的程序的示例：

import argparse

parser = argparse.ArgumentParser()
parser.add_argument("word", help="the string to be searched")
# you will want to set the type to int here as by default argparse parses all of the arguments as strings
parser.add_argument("point", type = int)
args = parser.parse_args()
word = args.word
point = args.point

在这种情况下，您将按照添加命令的相同顺序从命令行调用它，因此在您的情况下为python your_program.py the 7

欲了解更多信息，请参阅：https://docs.python.org/3/howto/argparse.html