Strings are used to send/communicate data over the network, but when this string is received by a program, it has to be converted into a data type that supports faster manipulations. In Python, there are dictionaries that allow the user to store data in the form of pairs or key-pair values. These are very similar to JSON, and in this post, you are going to learn how to convert a Python String into a dictionary.
The content of this guide is as follows:
- Method 1: Using the json.loads() Method to Convert String Into Dict
- Method 2: Using the ast.literal_eval() Method to Convert String Into Dict
- Method 3: Using strip() and split() in Generator Expressions
Let’s start with the first method right away.
Method 1: Using the json.loads() Method to Convert String Into Dict
The loads() method is used to “load” a JSON string and convert it into a JSON, or in Python, a Dictionary. However, for this method to work, the string has to be in the specific format in which each “key” is encapsulated by quotation marks, separated by a colon from the “value”. And every pair is separated by a comma.
To demonstrate the working of the loads() method for string-to-dictionary conversion, use the following code snippet:
stringVar = '{"Name":"John Doe", "Age" : "20", "Occupation": "Doctor"}'
resultVar = json.loads(stringVar)
print("Initial String: ",stringVar)
print("After Conversion: ",resultVar)
print("Type After Conversion: ",type(resultVar))
In this code snippet:
- The “json” module is imported so that the user can utilize the loads() method.
- After that, the string “stringVar” is initialized
- The loads() method is applied on the stringVar and the result is stored in the “resultVar” variable
- Lastly, the original string, the resultVar, and the type of the resultVar are printed onto the terminal.
When this code is executed, it produces the following outcome on the terminal:
In this output, you can easily notice that the string has been successfully converted to a dict data type in Python.
Method 2: Using the ast.literal_eval() Method to Convert String Into Dict
The literal_eval() method from the “ast” package can also be used to do exactly the same job as the loads() method from the “json” package. To use this method, take a look at the following code:
stringVar = '{"Name":"John Doe", "Age" : 20, "Occupation": "Doctor", "Salary" : 40000}'
resultVar = ast.literal_eval(stringVar)
print("Initial String: ",stringVar)
print("After Conversion: ",resultVar)
print("Type After Conversion: ",type(resultVar))
When this code is executed, it will produce the following result on the terminal:
The output verifies that the string has been successfully converted into a Python Dict.
Method 3: Using the eval() Method to Convert String Into Dict
Another very similar method is the eval() method which is used to evaluate whether a string is correctly formatted or not and returns the converted dictionary back to the caller. To see its working, take the following code example:
resultVar = eval(stringVar)
print("Using the eval() Method")
print("Initial String: ",stringVar)
print("After Conversion: ",resultVar)
print("Type After Conversion: ",type(resultVar))
When this code is executed, it will produce the following output on the terminal:
You have successfully converted a Python String into a Python dict using the eval() method.
Method 4: Using strip() and split() in Generator Expressions
Suppose that the string is not in the JSON String format, and you still want to convert it into a Python Dict. For this purpose, you would have to utilize various string manipulation methods like strip() and split(). For example, suppose the string contains key-value pairs, in which the key and value are separated by a hyphen “–”, and each pair is separated by a comma. For example, this is the string to be converted:
To do this, the user can utilize the generator expression, take a look at the following code:
resultVar = dict((a.strip(),b.strip())
for a,b in (section.split("-")
for section in stringVar.split(",")))
print("Initial String: ",stringVar)
print("AfterConversion: ",resultVar)
print("Type After Conversion: ",type(resultVar))
To understand this code, start from the innermost loop:
- The string is slit on every occurrence of a comma to get individual key-pairs
- For every key-pair substring, the string is split on the occurrence of a hyphen “–” and the two sections are allotted to variables “a” and “b”. The “a” holds the key part, whereas the “b” holds the value part.
- The strip() method is applied on both variables “a” and “b” to remove any blank spaces before or after the string.
- After that, both of these variables are passed into the dict() method to create a new Dictionary variable, “resultVar”
- Lastly, print the original string and the converted variable resultVar and its type onto the terminal using the print method()
When this code is executed, it produces the following output:
It can be easily observed that the string has been converted into a Python dict.
Conclusion
To convert a string into a Python “dict”, the user can use the loads() method from the “json” package or the literal_eval() method from the “ast” package. However, to use these two methods, the string should be a JSON String. Other than this, if the string is in a different format, then the user will have to use a combination of various string manipulation methods to come up with a working generator expression.
