Python - 在提取数据之前计算 JSON 元素

Python - Count JSON elements before extracting data

提问by Hyperion

I use an API which gives me a JSON file structured like this:

我使用了一个 API，它给了我一个结构如下的 JSON 文件：

{
offset: 0,
results: [
{
  source_link: "http://www.example.com/1",
  source_link/_title: "Title example 1",
  source_link/_source: "/1",
  source_link/_text: "Title example 1"
},
{
  source_link: "http://www.example.com/2",
  source_link/_title: "Title example 2",
  source_link/_source: "/2",
  source_link/_text: "Title example 2"
},
...

And I use this code in Python to extract the data I need:

我在 Python 中使用此代码来提取我需要的数据：

import json
import urllib2

u = urllib2.urlopen('myapiurl')
z = json.load(u)
u.close
link = z['results'][1]['source_link']
title = z['results'][1]['source_link/_title']

The problem is that to use it I have to know the number of the element from which I'm extracting the data. My resultscan have different length every time, so what I want to do is to count the number of elements in resultsat first, so I would be able to set up a loop to extract data from each element.

问题是要使用它，我必须知道从中提取数据的元素的编号。我results每次都可以有不同的长度，所以我想做的是首先计算元素的数量results，这样我就可以设置一个循环来从每个元素中提取数据。

采纳答案by LexyStardust

To check the length of the results key:

要检查结果键的长度：

len(z["results"])

But if you're just looping around them, a for loop is perfect:

但是如果你只是在它们周围循环，那么 for 循环是完美的：

for result in x["results"]:
    print(result["source_link"])

回答by fasouto

You didn't need to know the length of the result, you are fine with a for loop:

您不需要知道结果的长度，您可以使用 for 循环：

for result in z['results']:
    # process the results here

Anyway, if you want to know the length of 'results': len(z.results)

无论如何，如果您想知道“结果”的长度： len(z.results)

回答by crsxl

If you want to get the length, you can try:

如果你想得到长度，你可以尝试：

len(z['result'])

But in python, what we usually do is:

但是在python中，我们通常做的是：

for i in z['result']:
    # do whatever you like with `i`

Hope this helps.

希望这可以帮助。

回答by CrazyCasta

You don't need, or likely want, to count them in order to loop over them, you could do:

您不需要或可能不想计算它们以循环它们，您可以这样做：

import json
import urllib2

u = urllib2.urlopen('myapiurl')
z = json.load(u)
u.close
for result in z['results']:
    link = result['source_link']
    title = result['source_link/_title']
    # do something with link/title

Or you could do:

或者你可以这样做：

u = urllib2.urlopen('myapiurl')
z = json.load(u)
u.close
link = [result['source_link'] for result in z['results']]
title = [result['source_link/_title'] for result in z['results']]
# do something with links/titles lists

回答by Reut Sharabani

Few pointers:

几点指点：

1. No need to know results's length to iterate it. You can use for result in z['results'].
2. lists start from 0.
3. If you do need the index take a look at enumerate.

1. 不需要知道results的长度来迭代它。您可以使用for result in z['results'].
2. lists 从0.
3. 如果您确实需要索引，请查看enumerate.