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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
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How to Call SQL Query from Python

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Python's top supported database is MySQL. You can run SQL queries from Python. Here're best examples of how to connect to MYSQL and access MYSQL tables from Python.


Read: How to Print String in Next Line Easily


Here are Steps

  1. Import MySQL connecter
  2. Give user id, password details
  3. Issue SQL query


Python Logic to import MySQL connector


import mysql.connector


Note: If the MySQL connecter not installed in python, you need to install it using the below command.


pip3 install mysql-connector-python --allow-external mysql-connector-python


How to Call SQL Query from Python



Supply user id and Password


conn=mysql.connector.connect(user='root', password='password', host='localhost', database='sakila')



mycursor=conn.cursor()


Issue SQL Query



mycursor.execute("show tables") # you won't see any result. You need to give print.


print(mycursor.fetchall())


mycursor.execute("select * from customer") # you won't see any result. You need to give print.


print(mycursor.fetchall())


This way you can issue SQL queries in Python.


Read: Top 100 Hadoop Interview Questions 1 of 4

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