Python从JSON中提取值

时间:2013-04-08 13:11:04

标签: python json

我希望从JSON中提取值集并将它们写入文件。

JSON的格式如下:

    "interactions":     [
    {
        "type": "free",
        "input":             [
            [ 1, 4594, 119218, 0, [71, 46], [2295, 1492], [71, 46], [2295, 1492], 16017, 520790446, [71, 46, 71, 46], [71, 46, 71, 46] ],
            [ 1, 4594, 119219, 0, [72, 46], [2323, 1492], [72, 46], [2323, 1492], 26016, 520790456, [72, 46, 72, 46], [72, 46, 72, 46] ],
            [ 1, 4594, 119220, 0, [72, 45], [2323, 1464], [72, 45], [2323, 1464], 26016, 520790466, [72, 45, 72, 45], [72, 45, 72, 45] ],
            [ 1, 4594, 119221, 0, [72, 45], [2323, 1464], [72, 45], [2323, 1464], 26016, 520790476, [72, 45, 72, 45], [72, 45, 72, 45] ],
            [ 1, 4594, 119222, 0, [73, 45], [2350, 1464], [73, 45], [2350, 1464], 26016, 520790486, [73, 45, 73, 45], [73, 45, 73, 45] ],
            [ 1, 4594, 119223, 0, [73, 45], [2350, 1464], [73, 45], [2350, 1464], 26016, 520790496, [73, 45, 73, 45], [73, 45, 73, 45] ],
            [ 1, 4594, 119224, 0, [73, 45], [2350, 1464], [73, 45], [2350, 1464], 46000, 520790506, [73, 45, 73, 45], [73, 45, 73, 45] ]
        ]

我需要提取的是[71,46]列,然后是以520790446开头的列,并将其写入输出文件。

下面是我现在得到的代码:

import json

json_data = open("test_json.json")

data = json.load(json_data)

json_data.close()

# Need some sort of nested loop here to iterate through each line of the block, and each block also.
print data["interactions"][0]["input"][0][4], '\t', data["interactions"][0]["input"][0][9]

这些可变长度的块有几个,我需要提取所有值,直到文件结束。我虽然陷入了循环结构。

有人可以帮忙吗?

2 个答案:

答案 0 :(得分:2)

您可以获得如下数据:

[x[4] for x in data["interactions"][0]["input"]]

[x[9] for x in data["interactions"][0]["input"]]

或一次性,类似

[[x[4], x[9]] for x in data["interactions"][0]["input"]]

回答评论的第一部分:

[[x[4], x[9]] for x in interaction["input"] for interaction in data["interactions"]]

答案 1 :(得分:0)

def gen_vals(data):
    for i in xrange(len(data["interactions"])):
        for j in data["interactions"][i]["input"]:
            yield (j[4], j[9])

这是一个可以这样使用的生成器:

vals = [x for x in gen_vals(data)]