将元组转储为特定格式的YAML文件

Question

我有一个特定的格式，我想将元组转储到YAML文件中。我尝试运行以下代码将元组转储到YAML文件中。在下面的代码中，我尝试使用append()将一对元组(x，y)添加到列表中。在此之后，我会将列表转储回YAML文件。我的问题是，当我转储回YAML文件时，是否可以保持文件的特定格式不变？

import ruamel.yaml

def addObstacles():

    yaml = ruamel.yaml.YAML()
    with open('input.yaml') as f:
        doc = yaml.load(f)

    x = 5
    y = 6
    doc['map']['obstacles'].append(list((x,y)))

    with open('input.yaml', 'w') as f:
        yaml.dump(doc, f)

以下文件的输出如下：

map:
  dimensions: [8, 8]
  obstacles:
  - !!python/tuple [4, 5]
  - !!python/tuple [2, 0]
  - !!python/tuple [1, 1]
  - !!python/tuple [0, 5]
  - !!python/tuple [2, 5]
  - !!python/tuple [4, 4]
  - !!python/tuple [7, 5]
  - !!python/tuple [1, 4]
  - !!python/tuple [6, 7]
  - !!python/tuple [6, 3]
  - !!python/tuple [1, 7]
  - !!python/tuple [3, 6]
  - - 5
    - 6

该文件的预期输出如下：

map:
  dimensions: [8, 8]
  obstacles:
  - !!python/tuple [4, 5]
  - !!python/tuple [2, 0]
  - !!python/tuple [1, 1]
  - !!python/tuple [0, 5]
  - !!python/tuple [2, 5]
  - !!python/tuple [4, 4]
  - !!python/tuple [7, 5]
  - !!python/tuple [1, 4]
  - !!python/tuple [6, 7]
  - !!python/tuple [6, 3]
  - !!python/tuple [1, 7]
  - !!python/tuple [3, 6]
  - !!python/tuple [5, 6]

Answer 1

既然你追加了一个列表，你就会得到一个列表，但我假设你试过了，因为一个普通的元组不能工作，因为你实际上在ruamel.yaml中发现了一个bug。

只需两行代码并指定default_flow_style，就可以很容易地解决这个问题

import sys
import ruamel.yaml

if ruamel.yaml.version_info < (0, 16, 7):
   ruamel.yaml.representer.RoundTripRepresenter.add_representer(tuple, 
                         ruamel.yaml.representer.Representer.represent_tuple)

def addObstacles():

    yaml = ruamel.yaml.YAML()
    yaml.default_flow_style = None   # default is False, which would get you a block sequence
    with open('input.yaml') as f:
        doc = yaml.load(f)
    doc['map']['obstacles'].append((5, 6))

    yaml.dump(doc, sys.stdout)


addObstacles()

这样你就能得到你想要的东西：

map:
  dimensions: [8, 8]
  obstacles:
  - !!python/tuple [4, 5]
  - !!python/tuple [2, 0]
  - !!python/tuple [1, 1]
  - !!python/tuple [0, 5]
  - !!python/tuple [2, 5]
  - !!python/tuple [4, 4]
  - !!python/tuple [7, 5]
  - !!python/tuple [1, 4]
  - !!python/tuple [6, 7]
  - !!python/tuple [6, 3]
  - !!python/tuple [1, 7]
  - !!python/tuple [3, 6]   # add one after this
  - !!python/tuple [5, 6]

(我在我使用的YAML输入文件中添加了注释)。

Answer 2

我不确定你是否真的需要ruamel.yaml。PyYAML提供了您需要的开箱即用功能：

import yaml

def addObstacles():
    with open('in.yaml') as f:
        doc = yaml.load(f)

    doc['map']['obstacles'].append((5, 6))

    with open('out.yaml', 'w') as f:
        yaml.dump(doc, f)