The “left_join” Function in R

• Package: dplyr

• Purpose: To perform a left join between two data frames, merging them based on matching values in specified columns.

• General Class: Data Manipulation

• Required Argument(s):

• x, y: The data frames to be joined.

• by: Columns used for matching and merging.

• Notable Optional Arguments:

• suffix: A character vector of suffixes to be appended to duplicate and colliding column names.

• Example (with Explanation):

• # Load necessary packages
  library(dplyr)
  
  # Create two sample data frames
  data1 <- data.frame(
  ID = c(1, 2, 3),
  value1 = c(10, 15, 20)
  )
  
  data2 <- data.frame(
  ID = c(2, 3, 4),
  value2 = c(25, 30, 35)
  )
  
  # Perform a left join based on the 'ID' column
  joined_data <- left_join(data1, data2, by = "ID")
  
  # Display the joined data
  print(joined_data)

• In this example, the left_join function from the dplyr package is used to perform a left join between two sample data frames (data1 and data2) based on the matching values in the ‘ID’ column. The result, joined_data, contains all rows from data1 and matching rows from data2. This function is particularly useful when you want to combine data frames while preserving all rows from the left data frame.