How do I align the eol comments in ruamel.yaml so that they are all in the same column

Question

I am currently generating YAML files automatically with some configuration values. Sometimes these values have a comment attached and the comment is added to the YAML file.

Simple example

import sys
from ruamel.yaml import CommentedMap, YAML

top = CommentedMap()
top['sub_key1'] = data = CommentedMap()

data['a'] = 1
data['b'] = 'asdf'
data['c'] = 3.3333
data.yaml_add_eol_comment('comment 1', 'a')
data.yaml_add_eol_comment('comment 2', 'b')
data.yaml_add_eol_comment('comment 3', 'c')

top['sub_key2'] = data = CommentedMap()

data['a'] = 'long text'
data['b'] = 'an even longer text'
data.yaml_add_eol_comment('comment 4', 'a')
data.yaml_add_eol_comment('comment 5', 'b')

YAML().dump(top, sys.stdout)

This works and outputs this as expected

sub_key1:
  a: 1  # comment 1
  b: asdf # comment 2
  c: 3.3333 # comment 3
sub_key2:
  a: long text  # comment 4
  b: an even longer text # comment 5

However I'd really like to have the comments aligned like this (or even better with two spaces after the value).

sub_key1:
  a: 1      # comment 1
  b: asdf   # comment 2
  c: 3.3333 # comment 3
sub_key2:
  a: long text           # comment 4
  b: an even longer text # comment 5

I can't use the column parameter when adding the eol comment because the column is absolute from the start and I don't know

• on which level I am
• how long the generated key/value pair is
• what the current indentation i

Is there any way to align the comments after creation?

Answer 1

@Anthon: I modified your example a little bit for better readability. Thank you for your help

def align_comments(d, extra_indent=0):

    is_dict = isinstance(d, dict)
    if not is_dict and not isinstance(d, list):
        return None

    comments = d.ca.items.values()
    if comments:
        max_col = max(map(lambda x: x[2].column, comments), default=0)
        for comment in comments:
            comment[2].column = max_col + extra_indent

    for element in (d.values() if is_dict else d):
        align_comments(element, extra_indent=extra_indent)
    return None

Usage:

buf = io.BytesIO()
yaml.dump(top, buf)

top = yaml.load(buf.getvalue())
align_comments(top, extra=1)

yaml.dump(top, sys.stdout)