How can I parse a YAML file in Python?
11 Answers
First install pyyaml using pip3.
Then import yaml module and load the file into a dictionary called 'my_dict':
import yaml
with open('filename.yaml') as f:
my_dict = yaml.safe_load(f)
That's all you need. Now the entire yaml file is in 'my_dict' dictionary.
To access any element of a list in a YAML file like this:
global:
registry:
url: dtr-:5000/
repoPath:
dbConnectionString: jdbc:oracle:thin:@x.x.x.x:1521:abcd
You can use following python script:
import yaml
with open("/some/path/to/yaml.file", 'r') as f:
valuesYaml = yaml.load(f, Loader=yaml.FullLoader)
print(valuesYaml['global']['dbConnectionString'])
Example:
defaults.yaml
url: https://www.google.com
environment.py
from ruamel import yaml
data = yaml.safe_load(open('defaults.yaml'))
data['url']
I use ruamel.yaml. Details & debate here.
from ruamel import yaml
with open(filename, 'r') as fp:
read_data = yaml.load(fp)
Usage of ruamel.yaml is compatible (with some simple solvable problems) with old usages of PyYAML and as it is stated in link I provided, use
from ruamel import yaml
instead of
import yaml
and it will fix most of your problems.
EDIT: PyYAML is not dead as it turns out, it's just maintained in a different place.
I made my own script for this. Feel free to use it, as long as you keep the attribution. The script can parse yaml from a file (function load), parse yaml from a string (function loads) and convert a dictionary into yaml (function dumps). It respects all variable types.
# © didlly AGPL-3.0 License - github.com/didlly
def is_float(string: str) -> bool:
try:
float(string)
return True
except ValueError:
return False
def is_integer(string: str) -> bool:
try:
int(string)
return True
except ValueError:
return False
def load(path: str) -> dict:
with open(path, "r") as yaml:
levels = []
data = {}
indentation_str = ""
for line in yaml.readlines():
if line.replace(line.lstrip(), "") != "" and indentation_str == "":
indentation_str = line.replace(line.lstrip(), "").rstrip("\n")
if line.strip() == "":
continue
elif line.rstrip()[-1] == ":":
key = line.strip()[:-1]
quoteless = (
is_float(key)
or is_integer(key)
or key == "True"
or key == "False"
or ("[" in key and "]" in key)
)
if len(line.replace(line.strip(), "")) // 2 < len(levels):
if quoteless:
levels[len(line.replace(line.strip(), "")) // 2] = f"[{key}]"
else:
levels[len(line.replace(line.strip(), "")) // 2] = f"['{key}']"
else:
if quoteless:
levels.append(f"[{line.strip()[:-1]}]")
else:
levels.append(f"['{line.strip()[:-1]}']")
if quoteless:
exec(
f"data{''.join(str(i) for i in levels[:line.replace(line.lstrip(), '').count(indentation_str) if indentation_str != '' else 0])}[{key}]"
+ " = {}"
)
else:
exec(
f"data{''.join(str(i) for i in levels[:line.replace(line.lstrip(), '').count(indentation_str) if indentation_str != '' else 0])}['{key}']"
+ " = {}"
)
continue
key = line.split(":")[0].strip()
value = ":".join(line.split(":")[1:]).strip()
if (
is_float(value)
or is_integer(value)
or value == "True"
or value == "False"
or ("[" in value and "]" in value)
):
if (
is_float(key)
or is_integer(key)
or key == "True"
or key == "False"
or ("[" in key and "]" in key)
):
exec(
f"data{'' if line == line.strip() else ''.join(str(i) for i in levels[:line.replace(line.lstrip(), '').count(indentation_str) if indentation_str != '' else 0])}[{key}] = {value}"
)
else:
exec(
f"data{'' if line == line.strip() else ''.join(str(i) for i in levels[:line.replace(line.lstrip(), '').count(indentation_str) if indentation_str != '' else 0])}['{key}'] = {value}"
)
else:
if (
is_float(key)
or is_integer(key)
or key == "True"
or key == "False"
or ("[" in key and "]" in key)
):
exec(
f"data{'' if line == line.strip() else ''.join(str(i) for i in levels[:line.replace(line.lstrip(), '').count(indentation_str) if indentation_str != '' else 0])}[{key}] = '{value}'"
)
else:
exec(
f"data{'' if line == line.strip() else ''.join(str(i) for i in levels[:line.replace(line.lstrip(), '').count(indentation_str) if indentation_str != '' else 0])}['{key}'] = '{value}'"
)
return data
def loads(yaml: str) -> dict:
levels = []
data = {}
indentation_str = ""
for line in yaml.split("\n"):
if line.replace(line.lstrip(), "") != "" and indentation_str == "":
indentation_str = line.replace(line.lstrip(), "")
if line.strip() == "":
continue
elif line.rstrip()[-1] == ":":
key = line.strip()[:-1]
quoteless = (
is_float(key)
or is_integer(key)
or key == "True"
or key == "False"
or ("[" in key and "]" in key)
)
if len(line.replace(line.strip(), "")) // 2 < len(levels):
if quoteless:
levels[len(line.replace(line.strip(), "")) // 2] = f"[{key}]"
else:
levels[len(line.replace(line.strip(), "")) // 2] = f"['{key}']"
else:
if quoteless:
levels.append(f"[{line.strip()[:-1]}]")
else:
levels.append(f"['{line.strip()[:-1]}']")
if quoteless:
exec(
f"data{''.join(str(i) for i in levels[:line.replace(line.lstrip(), '').count(indentation_str) if indentation_str != '' else 0])}[{key}]"
+ " = {}"
)
else:
exec(
f"data{''.join(str(i) for i in levels[:line.replace(line.lstrip(), '').count(indentation_str) if indentation_str != '' else 0])}['{key}']"
+ " = {}"
)
continue
key = line.split(":")[0].strip()
value = ":".join(line.split(":")[1:]).strip()
if (
is_float(value)
or is_integer(value)
or value == "True"
or value == "False"
or ("[" in value and "]" in value)
):
if (
is_float(key)
or is_integer(key)
or key == "True"
or key == "False"
or ("[" in key and "]" in key)
):
exec(
f"data{'' if line == line.strip() else ''.join(str(i) for i in levels[:line.replace(line.lstrip(), '').count(indentation_str) if indentation_str != '' else 0])}[{key}] = {value}"
)
else:
exec(
f"data{'' if line == line.strip() else ''.join(str(i) for i in levels[:line.replace(line.lstrip(), '').count(indentation_str) if indentation_str != '' else 0])}['{key}'] = {value}"
)
else:
if (
is_float(key)
or is_integer(key)
or key == "True"
or key == "False"
or ("[" in key and "]" in key)
):
exec(
f"data{'' if line == line.strip() else ''.join(str(i) for i in levels[:line.replace(line.lstrip(), '').count(indentation_str) if indentation_str != '' else 0])}[{key}] = '{value}'"
)
else:
exec(
f"data{'' if line == line.strip() else ''.join(str(i) for i in levels[:line.replace(line.lstrip(), '').count(indentation_str) if indentation_str != '' else 0])}['{key}'] = '{value}'"
)
return data
def dumps(yaml: dict, indent="") -> str:
"""A procedure which converts the dictionary passed to the procedure into it's yaml equivalent.
Args:
yaml (dict): The dictionary to be converted.
Returns:
data (str): The dictionary in yaml form.
"""
data = ""
for key in yaml.keys():
if type(yaml[key]) == dict:
data += f"\n{indent}{key}:\n"
data += dumps(yaml[key], f"{indent} ")
else:
data += f"{indent}{key}: {yaml[key]}\n"
return data
print(load("config.yml"))
Example
config.yml
level 0 value: 0
level 1:
level 1 value: 1
level 2:
level 2 value: 2
level 1 2:
level 1 2 value: 1 2
level 2 2:
level 2 2 value: 2 2
Output
{'level 0 value': 0, 'level 1': {'level 1 value': 1, 'level 2': {'level 2 value': 2}}, 'level 1 2': {'level 1 2 value': '1 2', 'level 2 2': {'level 2 2 value': 2 2}}}
read_yaml_file function returning all data into a dictionary.
def read_yaml_file(full_path=None, relative_path=None):
if relative_path is not None:
resource_file_location_local = ProjectPaths.get_project_root_path() + relative_path
else:
resource_file_location_local = full_path
with open(resource_file_location_local, 'r') as stream:
try:
file_artifacts = yaml.safe_load(stream)
except yaml.YAMLError as exc:
print(exc)
return dict(file_artifacts.items())
Suggestion: Use yq (available via pip)
I'm Not sure how it wasn't suggested before, but I would highly recommend using yq which is a jq wrapper for YAML.
yq uses jq like syntax but works with yaml files as well as json.
Examples:
1 ) Read a value:
yq e '.a.b[0].c' file.yaml
2 ) Pipe from STDIN:
cat file.yaml | yq e '.a.b[0].c' -
3 ) Update a yaml file, inplace
yq e -i '.a.b[0].c = "cool"' file.yaml
4 ) Update using environment variables:
NAME=mike yq e -i '.a.b[0].c = strenv(NAME)' file.yaml
5 ) Merge multiple files:
yq ea '. as $item ireduce ({}; . * $item )' path/to/*.yml
6 ) Multiple updates to a yaml file:
yq e -i '
.a.b[0].c = "cool" |
.x.y.z = "foobar" |
.person.name = strenv(NAME)
' file.yaml
(*) Read more on how to parse fields from yaml with based on jq filters.
Additional references:
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