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To subset a data.table object by specifying columns that contains NA, we can follow the below steps −First of all, create a data.table object with some columns containing NAs.Then, use is.na along with subset function to subset the data.table object by specifying columns that contains NA.ExampleCreate the data.table objectLet’s create a data.table object as shown below −library(data.table) x1
To find the index of values in an R data frame column if they occur once, we can follow the below steps −First of all, create a data frame.Then, use which function along with duplicated function and single square brackets for subsetting to find the index of values in a column if they occur once.ExampleCreate the data frameLet’s create a data frame as shown below −x
To create a column with column name for maximum value in each row of an R data frame, we can follow the below steps −First of all, create a data frame.Then, use mutate function of dplyr package along with max.col function to create a column with column name for maximum value in each row of an R data frame.ExampleCreate the data frameLet’s create a data frame as shown below −x
To find the row variance of columns having same name in data.table object in R, we can follow the below steps −First of all, create a data.table object with some columns having same name.Then, use tapply along with colnames and var function to find the row variance of columns having same name.ExampleCreate the data.table objectLet’s create a data.table object as shown below −library(data.table) DT
To find the row mean of columns having same name in R data.table, 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 mean function to find the row mean of columns having same name.ExampleCreate the data.tableLet’s create a data.table as shown below −library(data.table) DT
To find the row standard deviation of columns having same name in R matrix, we can follow the below steps −First of all, create a matrix with some columns having same name.Then, use tapply along with colnames and sd function to find the row standard deviation of columns having same name.ExampleCreate the matrixLet’s create a matrix as shown below −M
To find the row mean of columns having same name in R matrix, we can follow the below steps −First of all, create a matrix with some columns having same name.Then, use tapply along with colnames and mean function to find the row mean of columns having same name.ExampleCreate the matrixLet’s create a matrix as shown below −M
To find the row mean 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 mean function to find the row mean of columns having same name.ExampleCreate the data frameLet’s create a data frame as shown below −df
To find the sin of each value in columns if some columns are categorical in R data frame, we can follow the below steps −First of all, create a data frame.Then, use numcolwise function from plyr package to find the sin of each value in columns if some columns are categorical.ExampleCreate the data frameLet’s create a data frame as shown below −Level
To convert values in alternate rows to negative R matrix, we can follow the below steps −First of all, create a matrix.Then, use vector multiplication with 1 and minus 1 to convert values in alternate rows to negative.ExampleCreate the matrixLet’s create a matrix as shown below −M