Category: Python Answers

Sometimes, we want to replace multiple substrings of a string with Python

In this article, we’ll look at how to replace multiple substrings of a string with Python.

How to replace multiple substrings of a string with Python?

To replace multiple substrings of a string with Python, we can call replace with each string we want to replace.

For instance, we write

def replace_all(text, dic):
    for i, j in dic.items():
        text = text.replace(i, j)
    return text

to loop through the dic dictionary.

We get the key and value as a tuple with items.

In the loop, we call text.replace with the string i in text that we want to replace with j.

Conclusion

To replace multiple substrings of a string with Python, we can call replace with each string we want to replace.

Sometimes, we want to add a method to an existing object instance with Python

In this article, we’ll look at how to add a method to an existing object instance with Python.

How to add a method to an existing object instance with Python?

To add a method to an existing object instance with Python, we just add the method directly to the class.

For instance, we write

def speak(self):
   return "hello"

SomeClass.speak = speak

to add the speak method to the SomeClass class by assigning SomeClass.speak to the speak function.

Then when we create a SomeClass instance, we can call speak as an instance method.

Conclusion

To add a method to an existing object instance with Python, we just add the method directly to the class.

Sometimes, we want to concatenate two lists in Python.

In this article, we’ll look at how to concatenate two lists in Python.

How to concatenate two lists in Python?

To concatenate two lists in Python, we can use the + operator.

For instance, we write

listone = [1, 2, 3]
listtwo = [4, 5, 6]

joinedlist = listone + listtwo

to combine listone and listtwo into one list and assign the joined list to joinedlist.

listtwo‘s entries will come after listone in joinedlist.

Conclusion

To concatenate two lists in Python, we can use the + operator.

Sometimes, we want to type hint a method with the type of the enclosing class with Python.

In this article, we’ll look at how to type hint a method with the type of the enclosing class with Python.

How to type hint a method with the type of the enclosing class with Python?

To type hint a method with the type of the enclosing class with Python, we can import the annotations module.

For instance, we write

from __future__ import annotations

class Position:
    def __add__(self, other: Position) -> Position:
        #...

to import the annotations module with

from __future__ import annotations

Then we can add type hints for arguments and return types.

We set other to have type Position by putting it after the colon.

And we set the return type of add to be Position by putting after the ->.

Conclusion

To type hint a method with the type of the enclosing class with Python, we can import the annotations module.

Sometimes, we want to check if a string is a number (float) with Python.

In this article, we’ll look at how to check if a string is a number (float) with Python.

How to check if a string is a number (float) with Python?

To check if a string is a number (float) with Python, we can use the isdigit method.

For instance, we write

b = "5657abc"
is_digit = b.isdigit()

to check if b is a number with isdigit.

Since b isn’t a number string, is_digit is False.

Conclusion

To check if a string is a number (float) with Python, we can use the isdigit method.