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How to Check Column Nulls and Replace: Pandas

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Here is a post that shows how to count Nulls and replace them with the value you want in the Pandas Dataframe. We have explained the process in two steps - Counting and Replacing the Null values. Count null values (column-wise) in Pandas ## count null values column-wise null_counts = df.isnull(). sum() print(null_counts) ``` Output: ``` Column1    1 Column2    1 Column3    5 dtype: int64 ``` In the above code, we first create a sample Pandas DataFrame `df` with some null values. Then, we use the `isnull()` function to create a DataFrame of the same shape as `df`, where each element is a boolean value indicating whether that element is null or not. Finally, we use the `sum()` function to count the number of null values in each column of the resulting DataFrame. The output shows the count of null values column-wise. to count null values column-wise: ``` df.isnull().sum() ``` ##Code snippet to count null values row-wise: ``` df.isnull().sum(axis=1) ``` In the above code, `df` is the Panda

How to Write Lambda Function Quickly in Python: 5 Examples

Here are the top python lambda function examples for your project and interviews. "Python's lambda functions are a powerful way to create small, anonymous functions on the fly. In this post, we'll explore some examples of how to use lambda functions in Python.


5 Best Python Lambda Function Examples


Lambda in python


#1 Sorting a List of Tuples by the Second Element

This lambda function sorts a list of tuples based on the second element of each tuple.


python code

my_list = [(1, 2), (4, 1), (9, 10), (13, 6), (5, 7)]

sorted_list = sorted(my_list, key=lambda x: x[1])

print(sorted_list)


Output:


[(4, 1), (1, 2), (13, 6), (5, 7), (9, 10)]

** Process exited - Return Code: 0 **

Press Enter to exit terminal


#2 Finding the Maximum Value in a List of Dictionaries

This lambda function finds the maximum value in a list of dictionaries based on a specific key.


python code

my_list = [{'name': 'Alice', 'age': 25}, {'name': 'Bob', 'age': 30}, {'name': 'Charlie', 'age': 20}]

max_age = max(my_list, key=lambda x: x['age'])

print(max_age)


Output:

{'name': 'Bob', 'age': 30}


** Process exited - Return Code: 0 **

Press Enter to exit terminal


#3 Multiplying Two Lists Element-Wise

This lambda function multiplies two lists element-wise and returns the result as a new list.


python code

list1 = [1, 2, 3, 4]

list2 = [5, 6, 7, 8]

result = list(map(lambda x, y: x * y, list1, list2))

print(result)

Output:


[5, 12, 21, 32]

** Process exited - Return Code: 0 **

Press Enter to exit terminal


#4 Filtering a List of Integers

This lambda function filters a list of integers and returns only the even numbers.


python code

my_list = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

even_numbers = list(filter(lambda x: x % 2 == 0, my_list))

print(even_numbers)

Output:


[2, 4, 6, 8, 10]

** Process exited - Return Code: 0 **

Press Enter to exit terminal


#5 Creating a Function That Returns a Function

This lambda function creates a function that returns another function that adds a constant value to its input.


python code

def add_constant(const):

    return lambda x: x + const


add5 = add_constant(5)

add10 = add_constant(10)


print(add5(3))

print(add10(3))


Output:

8

13


** Process exited - Return Code: 0 **

Press Enter to exit terminal


In the above example, add_constant is a function that returns a lambda function that adds the constant value to its input. add5 and add10 are two different functions that add 5 and 10 to their input, respectively.

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