Returning the value of a data.table column by column name that is stored in a string using get() is useful in several scenarios in R. Here are some examples:
data.table based on a user input or a variable value. For example, if you have a large data.table with many columns, and you want to allow users to select a column by name, you can use get() to retrieve the column based on the name stored in a string.data.table using a variable value. For example, if you have a data.table with a column named "oldname" and you want to rename it based on a user input or a variable value, you can use get() to retrieve the column based on its original name, and then assign the new name using setnames() function from data.table.get() to retrieve the column based on its name, and then apply any complex expression to the resulting vector.Using get() to retrieve a column based on its name stored in a string makes your code more flexible and dynamic, as it allows you to manipulate columns in a data.table without hardcoding their names. This can make your code more maintainable and adaptable to changing requirements over time.
To return the value of a column by column name that is stored in a string using data.table in R, you can use the get() function within the data.table syntax as follows:
Suppose you have a data.table named myDT and you want to extract the column with name stored in a string mycolname, you can do the following:
library(data.table)
# Create a sample data.table
myDT <- data.table(a = 1:5, b = 6:10, c = 11:15)
# Define the column name as a string
mycolname <- "b"
# Return the values of the column with the specified name
myDT[, get(mycolname)]
In this example, the output would be the values of the b column:
Note that get() returns the object named by the string argument provided, so get(mycolname) returns the object b, which is the column of the data.table you want to extract. By placing get(mycolname) inside the square brackets of myDT, you are telling R to extract the column named b from the data.table.