Python 3.5 - How to print a value with double quotes in YAML?

Question

I wanted to print a YAML file (with keys and values) and with some values between double quotes. I wanted to use the solution provide here: How to print a value with double quotes and spaces in YAML?

Unfortunately when I installed ruamel.yaml for python 3.5 (sudo apt install python3-ruamel.yaml) I was not able to find the function DoubleQuotedScalarString() in the script scalarstring.py . Here is what it looks like:

from __future__ import absolute_import
from __future__ import print_function

__all__ = ["ScalarString", "PreservedScalarString"]

try:
    from .compat import text_type
except (ImportError, ValueError):  # for Jython
    from ruamel.yaml.compat import text_type


class ScalarString(text_type):
    def __new__(cls, *args, **kw):
        return text_type.__new__(cls, *args, **kw)


class PreservedScalarString(ScalarString):
    def __new__(cls, value):
        return ScalarString.__new__(cls, value)


def preserve_literal(s):
    return PreservedScalarString(s.replace('\r\n', '\n').replace('\r', '\n'))


def walk_tree(base):
    """
    the routine here walks over a simple yaml tree (recursing in
    dict values and list items) and converts strings that
    have multiple lines to literal scalars
    """
    from ruamel.yaml.compat import string_types

    if isinstance(base, dict):
        for k in base:
            v = base[k]
            if isinstance(v, string_types) and '\n' in v:
                base[k] = preserve_literal(v)
            else:
                walk_tree(v)
    elif isinstance(base, list):
        for idx, elem in enumerate(base):
            if isinstance(elem, string_types) and '\n' in elem:
                print(elem)
                base[idx] = preserve_literal(elem)
            else:
                walk_tree(elem)

Currently this is what I obtain when using ruamel.yamp.dump() to get my yaml file:

key1: 0,0,0,0
key2: 0,0,0,0

And here is what I would like in my yaml file:

key1: "0,0,0,0"
key2: "0,0,0,0"

How am I suppose to solve this?

Answer 1

The class DoubleQuotedScalarString was added 2016-07-06.

You should update your version of ruamel.yaml e.g. using pip install -U ruamel.yaml. You can see what version you have by looking at the __init__.py in the yaml directory. The current version (June 2018) has:

version_info=(0, 15, 37),

In general it is best not to install additional python packages under Linux, using the package manager. Instead create a virtualenv for each program you want to develop and install all packages necessary for that program in such a virtualenv.