Python:从文件夹中读取多个json文件 [英] Python: Read several json files from a folder

问题描述

我想知道如何从单个文件夹中读取几个json文件(无需指定文件名，只是它们是json文件).

I would like to know how to read several json files from a single folder (without specifying the files names, just that they are json files).

还可以将它们转换为pandas DataFrame吗?

Also, it is possible to turn them into a pandas DataFrame?

能给我一个基本的例子吗?

Can you give me a basic example?

推荐答案

一种选择是使用

One option is listing all files in a directory with os.listdir and then finding only those that end in '.json':

import os, json
import pandas as pd

path_to_json = 'somedir/'
json_files = [pos_json for pos_json in os.listdir(path_to_json) if pos_json.endswith('.json')]
print(json_files)  # for me this prints ['foo.json']

现在您可以使用熊猫 DataFrame.from_dict 读取json(此时为python字典)到熊猫数据框:

Now you can use pandas DataFrame.from_dict to read in the json (a python dictionary at this point) to a pandas dataframe:

montreal_json = pd.DataFrame.from_dict(many_jsons[0])
print montreal_json['features'][0]['geometry']

打印:

{u'type': u'Point', u'coordinates': [-73.6051013, 45.5115944]}

在这种情况下，我将一些json附加到列表many_jsons中.我列表中的第一个json实际上是 geojson ，其中包含蒙特利尔的一些地理数据.我已经很熟悉内容了，所以我打印出了几何图形"，它给了我蒙特利尔的魅力.

In this case I had appended some jsons to a list many_jsons. The first json in my list is actually a geojson with some geo data on Montreal. I'm familiar with the content already so I print out the 'geometry' which gives me the lon/lat of Montreal.

以下代码总结了以上所有内容:

The following code sums up everything above:

import os, json
import pandas as pd

# this finds our json files
path_to_json = 'json/'
json_files = [pos_json for pos_json in os.listdir(path_to_json) if pos_json.endswith('.json')]

# here I define my pandas Dataframe with the columns I want to get from the json
jsons_data = pd.DataFrame(columns=['country', 'city', 'long/lat'])

# we need both the json and an index number so use enumerate()
for index, js in enumerate(json_files):
    with open(os.path.join(path_to_json, js)) as json_file:
        json_text = json.load(json_file)

        # here you need to know the layout of your json and each json has to have
        # the same structure (obviously not the structure I have here)
        country = json_text['features'][0]['properties']['country']
        city = json_text['features'][0]['properties']['name']
        lonlat = json_text['features'][0]['geometry']['coordinates']
        # here I push a list of data into a pandas DataFrame at row given by 'index'
        jsons_data.loc[index] = [country, city, lonlat]

# now that we have the pertinent json data in our DataFrame let's look at it
print(jsons_data)

这对我来说是打印的:

  country           city                   long/lat
0  Canada  Montreal city  [-73.6051013, 45.5115944]
1  Canada        Toronto  [-79.3849008, 43.6529206]

了解此代码对于在目录名"json"中有两个geojsons可能会有所帮助.每个json具有以下结构:

It may be helpful to know that for this code I had two geojsons in a directory name 'json'. Each json had the following structure:

{"features":
[{"properties":
{"osm_key":"boundary","extent":
[-73.9729016,45.7047897,-73.4734865,45.4100756],
"name":"Montreal city","state":"Quebec","osm_id":1634158,
"osm_type":"R","osm_value":"administrative","country":"Canada"},
"type":"Feature","geometry":
{"type":"Point","coordinates":
[-73.6051013,45.5115944]}}],
"type":"FeatureCollection"}

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