Convert YAML file to dictionary in Python [Practical Examples]

Convert YAML file to Dictionary in Python - Introduction

YAML is a digestible data serialization language that is often used to create configuration files with any programming language. It is designed for human interaction. YAML is a strict superset of JSON which is also a data serialization language. As it is a strict superset, it can do everything that JSON can and more. The advantage of using YAML files are that they portable across programming languages, extensive and support Unicode characters. It is more human-readable than other markup files like XML or even HTML for that matter. It supports a wide range of data types, including maps, lists and scalars. Many times in our application, we will need to write YAML file to python dictionary, or convert YAML file to dictionary in Python. We can accomplish this task using pyyaml library in Python.  

Installing PyYAML Library

PyYAML is a YAML parser and emitter for Python. We will use this library to parse YAML file. You can install with the following command on the windows/linux system. For linux system

 $ sudo pip install pyyaml

For windows system

pip install pyyaml

This will download and install python library to work on YAML files.  

Sample YAML file

This is a sample file saved as exampleyaml.yaml for network settings.

instance:
     Id: id2341
     environment: us-east
     serverId: s1342
     awsHostname: 192.168.0.10
     serverName: www.golinuxcloud.com
     ipAddr: 192.168.0.1
     roles: [webserver,php]

Different python functions used to convert YAML file to dictionary

Here, we will open and read YAML file and load it in the dictionary using the functions of PyYAML library. We will use following functions to open and load a YAML files.

• open - This function will open the file in read mode and store it as a stream.
• yaml.safe_load - This function converts a YAML document to a Python object. It will accept a byte string, a Unicode string, an open binary file object, or an open text file object as a parameter.
• yaml.load_all - Alternatively, we can also use load all function to load multiple yaml file together.

Apart from this, there are four loaders available for the load() function as shown below.

• BaseLoader - Loads all the basic YAML scalars as Strings
• SafeLoader - Loads subset of the YAML safely. It is mainly used if the input is from an untrusted source.
• FullLoader - Loads the full YAML but avoids arbitrary code execution. It will pose a potential risk when used for the untrusted input.
• UnsafeLoader - Original loader for untrusted inputs and generally used for backward compatibility.

 

Examples to convert YAML file to dictionary

Example 1 : Using safe_load function

In this example, we will open the file and save it in the stream variable. Thereafter, we will use stream to safe_load the yaml file in to the python object. Firstly, we will import pyyaml as yaml library. Then we open the data.yaml file using the open() function and use yaml.safe_load() function. We can also use yaml.load() function to load YAML file. The safe_load function will prevent python from executing any arbitrary code in the YAML file. Once the file is loaded we can display or process its values as per our requirement. The loaded YAML file works like a python object and we can reference its elements using keys.

# Program to convert yaml file to dictionary
import yaml
# opening a file
with open('exampleyaml.yaml', 'r') as stream:
    try:
    # Converts yaml document to python object
	d=yaml.safe_load(stream)
	
	# Printing dictionary
        print(d)
    except yaml.YAMLError as e:
        print(e)

Output

{'instance': {'environment': 'us-east', 'roles': ['webserver', 'php'], 'awsHostname': '192.168.0.10', 'serverName': 'www.golinuxcloud.com', 'ipAddr': '192.168.0.1', 'serverId': 's1342', 'Id': 'id2341'}}

 

Example 2 : Using BaseLoader

The data file named as data.yml.

fruits :
     name : Orange
     color : Orange
     type : Citrus
     taste : Sweet/Sour
     uses : Juice, pulp

In this example, we will open the file and save it in the stream variable. Thereafter, we will use BaseLoader to load the yaml file in to the python object.

# Program to convert yaml file to dictionary
import yaml
from yaml.loader import BaseLoader
# opening a file
with open('data.yaml', 'r') as stream:

    try:
        # Converts yaml document to python object
        d=yaml.load(stream, Loader=BaseLoader)
        for key, val in d.items():
            print(key, " : ", val,"\n")       
    except yaml.YAMLError as e:
        print(e)

Output

fruits  :  {'name': 'Orange', 'color': 'Orange', 'type': 'Citrus', 'taste': 'Sweet/Sour', 'uses': 'Juice, pulp'}

 

Example 3 : Using SafeLoader

The data file named as data.yml.

student:
     name : Ram
     dept : computer
     location : Hyderabad
     grade : 2
     specialization : AI, ML 

In this example, we will open the file and save it in the stream variable. Thereafter, we will use SafeLoader to load the yaml file in to the python object.

# Program to convert yaml file to dictionary
import yaml
from yaml.loader import SafeLoader
# opening a file
with open('data.yaml', 'r') as stream:

    try:
        # Converts yaml document to python object
        d=yaml.load(stream, Loader=SafeLoader)
        for key, val in d.items():
            print(key, " : ", val,"\n")       
    except yaml.YAMLError as e:
        print(e)

Output

student  :  {'name': 'Ram', 'dept': 'computer', 'location': 'Hyderabad', 'grade': 2, 'specialization': 'AI, ML'}

 

Example 4 : Using FullLoader

The data file named as data.yml.

student:
     name : Ram
     dept : computer
     location : Hyderabad
     grade : 2
     specialization : AI, ML 

In this example, we will open the file and save it in the stream variable. Thereafter, we will use FullLoader to load the yaml file in to the python object.

# Program to convert yaml file to dictionary
import yaml
from yaml.loader import FullLoader
# opening a file
with open('data.yaml', 'r') as stream:

    try:
        # Converts yaml document to python object
        d=yaml.load(stream, Loader=FullLoader)
        for key, val in d.items():
            print(key, " : ", val,"\n")       
    except yaml.YAMLError as e:
        print(e)

Output

student  :  {'name': 'Ram', 'dept': 'computer', 'location': 'Hyderabad', 'grade': 2, 'specialization': 'AI, ML'}

 

Example 5 : Using UnsafeLoader

The data file named as data.yml.

fruits :
     name : Orange
     color : Orange
     type : Citrus
     taste : Sweet/Sour
     uses : Juice, pulp

In this example, we will open the file and save it in the stream variable. Thereafter, we will use UnsafeLoader to load the yaml file in to the python object.

# Program to convert yaml file to dictionary
import yaml
from yaml.loader import UnsafeLoader
# opening a file
with open('data.yaml', 'r') as stream:

    try:
        # Converts yaml document to python object
        d=yaml.load(stream, Loader=UnsafeLoader)
        for key, val in d.items():
            print(key, " : ", val,"\n")       
    except yaml.YAMLError as e:
        print(e)

Output

fruits  :  {'name': 'Orange', 'color': 'Orange', 'type': 'Citrus', 'taste': 'Sweet/Sour', 'uses': 'Juice, pulp'}

 

Summary

The knowledge of converting yaml file to dictionary is very useful while working on real time applications. In many situations, we will need to read and convert yaml file to dictionary so as to use the key values stored in the dictionary for the further use. In this tutorial, we covered the functions and examples to convert yaml file to dictionary. We learned in detail about this with an example. All in all, this tutorial, covers everything that you need to know in order to have a clear view on how to convert yaml file to dictionary in Python.  

References

PyYAMLDocumentation