In this article, we are going to see how to add columns based on another column to the Pyspark Dataframe.
Creating Dataframe for demonstration:
Here we are going to create a dataframe from a list of the given dataset.
Python3
# Create a spark sessionfrom pyspark.sql import SparkSessionspark = SparkSession.builder.appName('SparkExamples').getOrCreate() # Create a spark dataframecolumns = ["Name", "Course_Name", "Months", "Course_Fees", "Discount", "Start_Date", "Payment_Done"]data = [ ("Amit Pathak", "Python", 3, 10000, 1000, "02-07-2021", True), ("Shikhar Mishra", "Soft skills", 2, 8000, 800, "07-10-2021", False), ("Shivani Suvarna", "Accounting", 6, 15000, 1500, "20-08-2021", True), ("Pooja Jain", "Data Science", 12, 60000, 900, "02-12-2021", False),] df = spark.createDataFrame(data).toDF(*columns) # View the dataframedf.show() |
Output:
Method 1: Using withColumns()
It is used to change the value, convert the datatype of an existing column, create a new column, and many more.
Syntax: df.withColumn(colName, col)
Returns: A new :class:`DataFrame` by adding a column or replacing the existing column that has the same name.
Python3
new_df = df.withColumn('After_discount', df.Course_Fees - df.Discount)new_df.show() |
Output:
Method 2: Using SQL query
Here we will use SQL query inside the Pyspark, We will create a temp view of the table with the help of createTempView() and the life of this temp is up to the life of the sparkSession. registerTempTable() will create the temp table if it is not available or if it is available then replace it.
Then after creating the table select the table by SQL clause which will take all the values as a string.
Python3
df.registerTempTable('table')newDF = spark.sql('select *, Course_Fees - Discount as Total from table')newDF.show() |
Output:
Method 3: Using UDF
In this method, we will define the user define a function that will take two parameters and return the total price. This function allows us to create a new function as per our requirements.
Now we define the data type of the UDF function and create the functions which will return the values which is the sum of all values in the row.
Python3
# import the functions as F from pyspark.sqlimport pyspark.sql.functions as Ffrom pyspark.sql.types import IntegerType # define the sum_coldef Total(Course_Fees, Discount): res = Course_Fees - Discount return res # integer datatype is definednew_f = F.udf(Total, IntegerType()) # calling and creating the new# col as udf_method_sumnew_df = df.withColumn( "Total_price", new_f("Course_Fees", "Discount")) # Showing the Dataframenew_df.show() |
Output:
