Category: Python Answers

Sometimes, we want to use a dictionary to count the items in a list with Python.

In this article, we’ll look at how to use a dictionary to count the items in a list with Python.

How to use a dictionary to count the items in a list with Python?

To use a dictionary to count the items in a list with Python, we can use a for loop.

For instance, we write

counts = dict()
for i in items:
  counts[i] = counts.get(i, 0) + 1

to create a for loop that loops through the items list.

In it, we add an entry to the counts dict which is set to counts.get(i, 0) + 1 to set the count to 1 is the dict entry with key i` not yet exist.

Otherwise, we increment the existing value by 1.

Conclusion

To use a dictionary to count the items in a list with Python, we can use a for loop.

Sometimes, we want to test NoneType in Python.

In this article, we’ll look at how to test NoneType in Python.

How to test NoneType in Python?

To test NoneType in Python, we can use the is operator.

For instance, we write

if variable is None:
    # ...

to check if variable is None.

Conclusion

To test NoneType in Python, we can use the is operator.

Sometimes, we want to make an immutable object in Python.

In this article, we’ll look at how to make an immutable object in Python.

How to make an immutable object in Python?

To make an immutable object in Python, we can use the dataclass decorator.

For instance, we write

from dataclasses import dataclass
from typing import Any

@dataclass(frozen=True)
class Immutable:
    a: Any
    b: Any

to create the Immutable class.

We decorate it with the dataclass decorator with frozen set to True to make the class create immutable objects when we instantiate the class.

Conclusion

To make an immutable object in Python, we can use the dataclass decorator.

Sometimes, we want to convert integer to binary in Python.

In this article, we’ll look at how to convert integer to binary in Python.

How to convert integer to binary in Python?

To convert integer to binary in Python, we use the string format method.

For instance, we write

b = '{0:08b}'.format(6)

to call '{0:08b}'.format with 6 to return the binary string with the value of 6 in binary.

Conclusion

To convert integer to binary in Python, we use the string format method.

Sometimes, we want to do double Iteration in list comprehension with Python.

In this article, we’ll look at how to do double Iteration in list comprehension with Python.

How to do double Iteration in list comprehension with Python?

To do double Iteration in list comprehension with Python, we can use 2 for expressions.

For instance, we write

l = [word for sentence in text for word in sentence]

to loop through the sentence in the text list with

for sentence in text

In it, we have another loop to loop the the word in the sentence list.

for word in sentence

And then we put the word strings in the list l.

Conclusion

To do double Iteration in list comprehension with Python, we can use 2 for expressions.