在python中创建一个JSON对象

Question

我想创建一个JSON对象并将其附加到列表中，但没有成功。 我得到这个错误按摩：

Traceback (most recent call last): 
    File "/projects/circos/test.py", line 32, in <module> 
    read_relationship('data/chr03_small_n10.blast') 
    File "/projects/circos/test.py", line 20, in read_relationship 
    tmp = ("[source: {id: '{}',start: {},end: {}},target: {id: '{}',start: {}, end: {}}],").format(parts[0],parts[2],parts[3],parts[1],parts[4],parts[5]) 
KeyError: 'id' 

用下面的代码

def read_relationship(filename): 
    data = [] 
    with open(filename) as f: 
     f.next() 
     for line in f: 
      try: 
       parts = line.rstrip().split('\t') 
       query_name = parts[0] 
       subject_name = parts[1] 
       query_start = parts[2] 
       query_end = parts[3] 
       subject_start = parts[4] 
       subject_end = parts[5] 


       # I need: [source: {id: 'Locus_1', start: 1, end: 1054}, target: {id: 'tig00007234', start: 140511, end: 137383}], 
       tmp = ("[source: {id: '{}',start: {},end: {}},target: {id: '{}',start: {}, end: {}}],").format(parts[0],parts[2],parts[3],parts[1],parts[4],parts[5]) 
       data.append(tmp) 

      except ValueError: 
       pass 

    with open('data/data.txt', 'w') as outfile: 
     json.dump(data, outfile) 


read_relationship('data/chr03_small_n10.blast') 

我错过了什么？

Answer 1

您正在使用json.dump（）函数错误。

你传递一个对象和文件对象：对键值映射

json.dump(object, fileobject) 

使用字典：

def read_relationship(filename): 
    data = [] 
    with open(filename) as f: 
     f.next() 
     for line in f: 
      try: 
       parts = line.rstrip().split('\t') 
       query_name = parts[0] 
       subject_name = parts[1] 
       query_start = parts[2] 
       query_end = parts[3] 
       subject_start = parts[4] 
       subject_end = parts[5] 

       # use dict here 
       item = { 
        'source': { 
         'id': query_name, 
         'start': subject_name, 
         'end': query_start 
       }, 
        'target': { 
         'id': query_end, 
         'start': subject_start, 
         'end': subject_end 
        } 
       } 
       data.append(item) 

      except ValueError: 
       pass 

    with open('data/data.txt', 'w') as outfile: 
     json.dump(data, outfile) 


read_relationship('data/chr03_small_n10.blast') 

Answer 2

您需要double{和}不是占位符的字符; {id:...}被视为以其他方式命名占位符：

tmp = (
    "[source: {{id: '{}',start: {},end: {}}}," 
    "target: {{id: '{}',start: {}, end: {}}}],").format(
     parts[0], parts[2], parts[3], parts[1], parts[4], parts[5]) 

的{{和}}序列结束在结果单{和}字符。

而不是把你所有的部件在单独，使用编号插槽：

tmp = (
    "[source: {{id: '{0}',start: {2},end: {3}}}," 
    "target: {{id: '{1}',start: {4}, end: {5}}}],").format(
     *parts) 

你应该考虑使用csv模块读取您的TSV的数据，如果你的意思是针对上述数据是部分JSON文档（不是嵌入字符串，而是单独的JSON数组和对象），然后将其格式化为字符串将不起作用。

您需要将您的CSV列的第一转换为整数，但：

import csv 
import json 

def read_relationship(filename): 
    data = [] 
    with open(filename, 'rb') as f: 
     reader = csv.reader(f, delimiter='\t') 
     next(reader, None) 
     for row in reader: 
      data.append([{ 
       'source': { 
        'id': row[0], 
        'start': int(row[2]), 
        'end': int(row[3]), 
       }, 
       'target': { 
        'id': row[1], 
        'start': int(row[4]), 
        'end': int(row[5]), 
       }, 
      }]) 

    with open('data/data.txt', 'w') as outfile: 
     json.dump(data, outfile)