Author: John Au-Yeung

Sometimes, we want to count the occurrences of a list item with Python.

In this article, we’ll look at how to count the occurrences of a list item with Python.

How to count the occurrences of a list item with Python?

To count the occurrences of a list item with Python, we can use the JavaScript array’s count method.

For instance, we write:

print([1, 2, 3, 4, 1, 4, 1].count(1))

to call count on the array to find the number of times the value 1 is in the array.

Therefore, 3 is printed since 1 appeared 3 times in the array.

Conclusion

To count the occurrences of a list item with Python, we can use the JavaScript array’s count method.

Sometimes, we want to add static methods in Python classes.

In this article, we’ll look at how to add static methods in Python classes.

How to add static methods in Python classes?

To add static methods in Python classes, we use the @staticmethod decorator.

For instance, we write:

class C:
    @staticmethod
    def f():
      print('static')

C.f()      

We make f a static method with the @staticmethod decorator.

Then we call C.f dirertly without instantiating C.

Therefore, we see 'static' printed.

Conclusion

To add static methods in Python classes, we use the @staticmethod decorator.

Sometimes, we want to remove an element from a list by index with Python.

In this article, we’ll look at how to remove an element from a list by index with Python.

How to remove an element from a list by index with Python?

To remove an element from a list by index with Python, we can use the del operator.

For instance, we write:

a = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
del a[-1]
print(a)

to remove the last element by passing in index -1 into the square brackets.

Therefore, a is [0, 1, 2, 3, 4, 5, 6, 7, 8] after del is used.

We can also use del to remove elements from the starting index to the ending index minus one.

For instance, we write:

a = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
del a[2:4]
print(a)

to remove elements from a with index 2 and 3.

Therefore, a is [0, 1, 4, 5, 6, 7, 8, 9] after del is used.

Conclusion

To remove an element from a list by index with Python, we can use the del operator.

Sometimes, we want to print literal curly-brace characters in a string and also use .format it with Python.

In this article, we’ll look at how to print literal curly-brace characters in a string and also use .format it with Python.

How to print literal curly-brace characters in a string and also use .format it with Python?

To print literal curly-brace characters in a string and also use .format it with Python, we can use double curly braces in the string.

For instance, we write:

x = " {{ Hello }} {0} "
print(x.format('jane'))

to surround ‘Hello’ with double curly braces, which will be return a string with single curly braces surround it.

Therefore, we get ' { Hello } jane ' returned and printed.

Conclusion

To print literal curly-brace characters in a string and also use .format it with Python, we can use double curly braces in the string.

Sometimes, we want to limit floats to two decimal points with Python.

In this article, we’ll look at how to limit floats to two decimal points with Python.

How to limit floats to two decimal points with Python?

To limit floats to two decimal points with Python, we can use the format function.

For instance, we write:

a = 13.949999999999999
b = format(a, '.2f')
print(b)

to call format with number a, and '.2f' to return a rounded to 2 decimal places.

And we assign the returned result to b.

Therefore, b is 13.95.

Conclusion

To limit floats to two decimal points with Python, we can use the format function.