从 JSON 文件计数到 python

Question

[
{
"frame_id":2, 
 "filename":"sample_imgs/2.jpg", 
 "objects": [ 
  {"class_id":8, "name":"boat", "relative_coordinates":{"left_x":1547, "top_y":1126, "width": 298, "height": 149}, "confidence":0.348690}, 
  {"class_id":0, "name":"person", "relative_coordinates":{"left_x": 128, "top_y":1327, "width":  30, "height":  89}, "confidence":0.972903}, 
  {"class_id":0, "name":"person", "relative_coordinates":{"left_x": 179, "top_y":1332, "width":  26, "height":  72}, "confidence":0.689888}, 
  {"class_id":0, "name":"person", "relative_coordinates":{"left_x":  79, "top_y":1324, "width":  29, "height":  73}, "confidence":0.663020}, 
  {"class_id":0, "name":"person", "relative_coordinates":{"left_x": 520, "top_y":1374, "width":  40, "height":  79}, "confidence":0.657240}, 
  {"class_id":0, "name":"person", "relative_coordinates":{"left_x": 565, "top_y":1367, "width":  36, "height":  84}, "confidence":0.447690}, 
  {"class_id":0, "name":"person", "relative_coordinates":{"left_x": 521, "top_y":1355, "width":  34, "height":  41}, "confidence":0.412204}, 
  {"class_id":0, "name":"person", "relative_coordinates":{"left_x": 159, "top_y":1318, "width":  27, "height":  77}, "confidence":0.306808}
 ]

如何使用 Python 解析文件并计算 JSON 文件中存在的 ID 数量？ 我使用的代码显示了所有数据，但 id 类似于缩小范围，例如

"person": 7, 
"boat": 1

这是我的代码

import json
from collections import Counter

with open('/home/output/result.json') as json_data:
    data = json.load(json_data)
    c = Counter(k[4:] for d in data for k, v in d.items() if k.startswith('class_id'))
print(data)
print(json.dumps(c, indent=2, sort_keys=True))

Answer 1

data = [
{
"frame_id":2, 
 "filename":"sample_imgs/2.jpg", 
 "objects": [ 
  {"class_id":8, "name":"boat", "relative_coordinates":{"left_x":1547, "top_y":1126, "width": 298, "height": 149}, "confidence":0.348690}, 
  {"class_id":0, "name":"person", "relative_coordinates":{"left_x": 128, "top_y":1327, "width":  30, "height":  89}, "confidence":0.972903}, 
  {"class_id":0, "name":"person", "relative_coordinates":{"left_x": 179, "top_y":1332, "width":  26, "height":  72}, "confidence":0.689888}, 
  {"class_id":0, "name":"person", "relative_coordinates":{"left_x":  79, "top_y":1324, "width":  29, "height":  73}, "confidence":0.663020}, 
  {"class_id":0, "name":"person", "relative_coordinates":{"left_x": 520, "top_y":1374, "width":  40, "height":  79}, "confidence":0.657240}, 
  {"class_id":0, "name":"person", "relative_coordinates":{"left_x": 565, "top_y":1367, "width":  36, "height":  84}, "confidence":0.447690}, 
  {"class_id":0, "name":"person", "relative_coordinates":{"left_x": 521, "top_y":1355, "width":  34, "height":  41}, "confidence":0.412204}, 
  {"class_id":0, "name":"person", "relative_coordinates":{"left_x": 159, "top_y":1318, "width":  27, "height":  77}, "confidence":0.306808}
 ]
}]

import json
from collections import Counter
counter = Counter(obj.get('name') for item in data for obj in item['objects'])
print(counter.most_common())
with open('data.json', 'w') as f:
    json.dump(counter, f, indent=4

)

输出

[('person', 7), ('boat', 1)]

数据.json

{
    "boat": 1,
    "person": 7
}

这假设您在 JSON 文件中可能有多个帧并一次处理所有帧。当然你可以把counter转换成dict

Answer 2

假设你有数据文件a.json，你可以使用pandas和json来操作数据。

import json
import pandas as pd

with open('a.json') as fi:
    jdata = json.load(fi)


df = pd.DataFrame(data=jdata[0]['objects'])
output = df['name'].value_counts().to_dict()
print(output)

with open('output.json','w') as fo:
    json.dump(output,fo,indent=4)

输出

{'boat': 1, 'person': 7}