將 Python 字典中的列表轉儲到 YAML 文件中作為示例

Question

我有一個 Python 字典，如下所示，我想將它轉儲到 YAML 文件中。 我想將這些示例轉儲為字符串示例列表而不是單個鍵（ examples后面有一個 pipe | 。我該怎么做？

data = {'version': '1.0',
 'food': [{'category': 'japanese', 'examples': ['sushi', 'ramen', 'sashimi']},
 {'category': 'chinese', 'examples': ['hotpot', 'noodle', 'fried rice']}]}

yaml.SafeDumper.ignore_aliases = lambda *args : True
with open('food.yml', 'w', encoding = "utf-8") as yaml_file:
    dump = yaml.safe_dump(data,
                          default_flow_style=False,
                          allow_unicode=False,
                          encoding=None,
                          sort_keys=False,
                          line_break=10)
    yaml_file.write(dump)

結果

version: '1.0'
food:
- category: japanese
  examples:
  - sushi
  - ramen
  - sashimi
- category: chinese
  examples:
  - hotpot
  - noodle
  - fried rice

預期的

version: '1.0'
food:
- category: japanese
  examples: |
    - sushi
    - ramen
    - sashimi
- category: chinese
  examples: |
    - hotpot
    - noodle
    - fried rice

Answer 1

帶有|的構造是文字樣式標量。 並且在其縮進的上下文中，前導破折號沒有特殊含義（即不被解析為塊樣式序列指示符）。 PyYAML 不支持在不添加表示器的情況下在單個字符串上使用這些文字標量。

PyYAML only supports a subset of YAML 1.1 and that specification was superseded in 2009. The recommended extension for files containing YAML documents has been .yaml since at least [September 2006]( https://web.archive.org/w eb/20060924190202 /http://yaml.org/faq.html)。

目前尚不清楚為什么要使用這些過時的庫和約定，但看起來是時候升級了：

import sys
import ruamel.yaml

def literal(*args):
    # convert args to a multiline string that looks like block sequence
    # convert to string in case non-strings were passed in
    return ruamel.yaml.scalarstring.LiteralScalarString(
               '- ' + '\n- '.join([str(x) for x in args]) + '\n'
           )   

data = {'version': '1.0',
 'food': [{'category': 'japanese', 'examples': literal('sushi', 'ramen', 'sashimi')},
 {'category': 'chinese', 'examples': literal('hotpot', 'noodle', 'fried rice')}]}

    
yaml = ruamel.yaml.YAML()
yaml.dump(data, sys.stdout)

這使：

version: '1.0'
food:
- category: japanese
  examples: |
    - sushi
    - ramen
    - sashimi
- category: chinese
  examples: |
    - hotpot
    - noodle
    - fried rice