Finding the position of a substring within a string using PySpark

pyspark.sql.functions.locate

PySpark, a tool for handling large-scale data processing, offers a plethora of functions for string manipulation, one of which is the locate function. This article will delve into the locate function in PySpark, exploring its advantages and demonstrating its use in a real-world scenario. The locate function in PySpark is a versatile and efficient tool for string manipulation, particularly useful for parsing and analyzing large datasets.

The locate function in PySpark is used to find the position of a substring within a string. It returns the location of the first occurrence of the substring. If the substring is not found, the function returns 0. The syntax of the locate function is:

locate(substring, string, pos)

substring: The substring to search for.
string: The string in which to search.
pos: The position in string to start searching (optional; defaults to 1).

Advantages of using locate

• Efficiency: Quickly identifies the position of a substring, which is especially useful in large datasets.
• Flexibility: Can be used in various data processing and transformation scenarios.
• Ease of Use: Simple syntax and integrates seamlessly with other PySpark functions.

Use case: Identifying key words in names

Consider a dataset with names: Sachin, Ram, Raju, David, and Wilson. We want to determine if these names contain a particular set of letters, such as ‘am’.

Example

Objective

Determine the position of ‘am‘ in each name.

Implementation in PySpark

First, let’s set up the PySpark environment and create our DataFrame:

from pyspark.sql import SparkSession
from pyspark.sql.functions import locate
# Initialize Spark Session
spark = SparkSession.builder.appName("Locate Example").getOrCreate()
# Sample Data
data = [("Sachin",), ("Ram",), ("Raju",), ("David",), ("Wilson",)]
# Creating DataFrame
df = spark.createDataFrame(data, ["Name"])
df.show()

Output

+------+
|  Name|
+------+
|Sachin|
|   Ram|
|  Raju|
| David|
|Wilson|
+------+

Next, apply the locate function:

# Using Locate Function
locate_df = df.withColumn("Position", locate("am", df.Name))
locate_df.show()

This will yield the position of ‘am’ in each name, if present:

Spark important urls to refer

1. Spark Examples
2. PySpark Blogs
3. Bigdata Blogs
4. Spark Interview Questions
5. Official Page