PyYAML错误：“yaml.scanner.scannerror:此处不允许映射值”

Question

解析YAML时出现一个奇怪的错误：

yaml.scanner.ScannerError: mapping values are not allowed here

根据YAML Lint，我试图读取的YAML文件是有效的

另一件奇怪的事情是，它在我的笔记本电脑（Arch Linux）上运行良好，但在服务器（Ubuntu）上运行不好。PyYAML版本在两台机器上都是相同的。

我见过the other posts on stackoverflow where people were missing the space after the colon，但我没有遗漏任何空格。

这是完整的YAML文件：

pipeline:
    - read:
            input: /home/omnibrain/projects/company/data/data.csv
            output: some_data
    - filter:
            input: some_data
            filtername: latlng_filter
            minlat: 32.5
            maxlat: 32.9
            minlng: -117.4
            maxlng: -117.0
    - enhance:
            input: some_data
            enhancername: geo_enhancer
            fields: zip
    - write:
            input: some_data
            writername: csv_writer
            output_dir: /home/omnibrain/outputs
            columns: [id, latitude, longitude, zip, networktype]
            filename: example1 # the output filename

这是完整的堆栈跟踪：

Traceback (most recent call last):
  File "/usr/local/bin/someproject", line 9, in <module>
    load_entry_point('someproject==0.0.1', 'console_scripts', 'someproject')()
  File "/usr/local/lib/python3.4/dist-packages/someproject-0.0.1-py3.4.egg/someproject/__init__.py", line 19, in main
    pipeline.Pipeline(parser.parse_args().scriptfile).start()
  File "/usr/local/lib/python3.4/dist-packages/someproject-0.0.1-py3.4.egg/someproject/pipeline/pipeline.py", line 20, in __init__
    self._raw_pipeline = self._parse_yaml(yamlscript)
  File "/usr/local/lib/python3.4/dist-packages/someproject-0.0.1-py3.4.egg/someproject/pipeline/pipeline.py", line 55, in _parse_yaml
    data = yaml.load(yamlscript)
  File "/usr/local/lib/python3.4/dist-packages/PyYAML-3.11-py3.4-linux-x86_64.egg/yaml/__init__.py", line 72, in load
  File "/usr/local/lib/python3.4/dist-packages/PyYAML-3.11-py3.4-linux-x86_64.egg/yaml/constructor.py", line 35, in get_single_data
  File "/usr/local/lib/python3.4/dist-packages/PyYAML-3.11-py3.4-linux-x86_64.egg/yaml/composer.py", line 36, in get_single_node
  File "/usr/local/lib/python3.4/dist-packages/PyYAML-3.11-py3.4-linux-x86_64.egg/yaml/composer.py", line 55, in compose_document
  File "/usr/local/lib/python3.4/dist-packages/PyYAML-3.11-py3.4-linux-x86_64.egg/yaml/composer.py", line 84, in compose_node
  File "/usr/local/lib/python3.4/dist-packages/PyYAML-3.11-py3.4-linux-x86_64.egg/yaml/composer.py", line 133, in compose_mapping_node
  File "/usr/local/lib/python3.4/dist-packages/PyYAML-3.11-py3.4-linux-x86_64.egg/yaml/composer.py", line 82, in compose_node
  File "/usr/local/lib/python3.4/dist-packages/PyYAML-3.11-py3.4-linux-x86_64.egg/yaml/composer.py", line 111, in compose_sequence_node
  File "/usr/local/lib/python3.4/dist-packages/PyYAML-3.11-py3.4-linux-x86_64.egg/yaml/composer.py", line 84, in compose_node
  File "/usr/local/lib/python3.4/dist-packages/PyYAML-3.11-py3.4-linux-x86_64.egg/yaml/composer.py", line 133, in compose_mapping_node
  File "/usr/local/lib/python3.4/dist-packages/PyYAML-3.11-py3.4-linux-x86_64.egg/yaml/composer.py", line 84, in compose_node
  File "/usr/local/lib/python3.4/dist-packages/PyYAML-3.11-py3.4-linux-x86_64.egg/yaml/composer.py", line 127, in compose_mapping_node
  File "/usr/local/lib/python3.4/dist-packages/PyYAML-3.11-py3.4-linux-x86_64.egg/yaml/parser.py", line 98, in check_event
  File "/usr/local/lib/python3.4/dist-packages/PyYAML-3.11-py3.4-linux-x86_64.egg/yaml/parser.py", line 428, in parse_block_mapping_key
  File "/usr/local/lib/python3.4/dist-packages/PyYAML-3.11-py3.4-linux-x86_64.egg/yaml/scanner.py", line 116, in check_token
  File "/usr/local/lib/python3.4/dist-packages/PyYAML-3.11-py3.4-linux-x86_64.egg/yaml/scanner.py", line 220, in fetch_more_tokens
  File "/usr/local/lib/python3.4/dist-packages/PyYAML-3.11-py3.4-linux-x86_64.egg/yaml/scanner.py", line 580, in fetch_value
yaml.scanner.ScannerError: mapping values are not allowed here
  in "./test1.yaml", line 3, column 93

Answer 1

冒号后面没有空格，以input: /home/omnibrain/projects/company/data/data.csv开头的行中有太多的空格。这就是为什么你会看到第3行第93列

整行字的意思是：

      input: /home/omnibrain/projects/company/data/data.csv                           output: some_data

它还应该有一些有趣的字符来干扰您的显示，通常情况下，您会看到一个字符串

...                           output: some_data

下面是这里不允许的映射。

如果文件看起来相同，通常会出现这种差异，但实际上并非如此，例如在从一个终端复制和粘贴到另一个终端之后。或者在粘贴到YAMLlint这样的网站之后。

在两个系统上生成一个md5sum，以便文件检查它们是否真的相同。在YAML文件上使用od -c检查是否有奇怪的字符。