Python从JSON提取值

Question

我正在寻找从JSON中提取值集并将其写入文件的方法。

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。

以下是我目前所获得的代码：

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]

其中有几个可变长度的块，我需要提取所有值，直到文件结束。 我仍然停留在循环结构中。

有人可以帮忙吗？

Answer 1

您可以像这样获得数据：

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

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

或一口气

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

要回答评论的第一部分：

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

Answer 2

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)]