To find the row total of columns having same name in data.table object in R, we can follow the below steps −First of all, create a data.table with some columns having same name.Then, use tapply along with colnames and sum function to find the row total of columns having same name.ExampleCreate the data.tableLet’s create a data.table as shown below −library(data.table) DT

To extract the last n values of all elements of a list in R, we can follow the below steps −First of all, create a list.Then, use tail function with sapply function to extract the last n values of all elements in the list.Example 1Create the listLet’s create a list as shown below −List1

To find the row total of columns having same name in R data frame, we can follow the below steps −First of all, create a data frame with some columns having same name.Then, use tapply along with colnames and sum function to find the row total of columns having same name.ExampleCreate the data frameLet’s create a data frame as shown below −df

To apply two sample t test using a categorical column in R data frame, we can follow the below steps −First of all, create a data frame.Then, use t.test function with categorical column and numerical column linked with ~ sign.ExampleCreate the data frameLet’s create a data frame as shown below −Gender

To create a boxplot of single column in R data frame with column name, we can follow the below steps −First of all, create a data frame with single numerical column and create the boxplot for that column using boxplot function.Then, create the same boxplot with show.names argument set to TRUE.ExampleCreate the boxplotUsing boxplot function to create a boxplot for single column of a data frame as shown below −x

To find the percentage of values that lie within a range in single column R matrix, we can follow the below steps −First of all, create a matrix.Then, use sum function along with extreme values for range and length function to find the percentage of values that lie within that range.ExampleCreate the data frameLet’s create a data frame as shown below −M

To create a column of product in data frames stored in R list, we can follow the below steps −First of all, create a list of data frames.Then, use lapply function to create a column of product in data frames stored in the list.ExampleCreate the list of data framesUsing data.frame function to create data frames and list function to create the list of those data frames −df1

To combine two rows in R data frame by addition, we can follow the below steps −First of all, create a data frame.Then, using plus sign (+) to add two rows and store the addition in one of the rows.After that, remove the row that is not required by subsetting with single square brackets.ExampleCreate the data frameLet’s create a data frame as shown below −x

To replace NAs with 0 in an R list that contains data.table objects, we can follow the below steps −First of all, create a list of data.table objects that contain some NAs.Then, use lapply function and is.na function to replace NAs with 0 in the list.ExampleCreate the listLet’s create a list as shown below −library(data.table) DT1

To remove hash at last position from every value in R data frame column, we can follow the below steps −First of all, create a data frame with a column having hash at last position in every value.Then, use gsub function to remove hash at last position from every value in the column.ExampleCreate the data frameLet’s create a data frame as shown below −x