To write text outside plot using ggplot2, we can use annotate function and coord_cartesian function. The annotate function will define the text value and the coord_cartesian function will define the position of the text outside the plot area.Check out the below example to understand how it works.ExampleFollowing snippet creates a sample data frame −x

To create a column of division 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 division 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 cut a data frame column with minimum value, we need to specify the minimum value withing cut function with the help of min function and set the include.lowest argument to TRUE. We can also specify the maximum value so that the maximum value is also taken into account while cutting the column.Example 1Following snippet creates a sample data frame −x

To create a column of difference 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 difference 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 create a matrix with only one row in R, we can set the nrow argument of matrix function to 1.For example, if we want to create a matrix say M with only one row then it can be done by using the command given below −M

To combine two rows in data.table object in R by addition, we can follow the below steps −First of all, create a data.table object.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.table objectLet’s create a data.table object as shown below: −library(data.table) x

To create a column of total 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 total 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 find the mean of multiple columns based on multiple grouping columns in R data frame, we can use summarise_at function with mean function.For Example, if we have a data frame called df that contains two grouping columns say G1 and G2 and two numerical columns say Num1 and Num2 then we can find the mean of Num1 and Num2 based on G1 and G2 by using the below mentioned command −df%%group_by(G1,G2)%%summarise_at(vars("Num1","Num2"),mean)Example 1Following snippet creates a sample data frame −Gender

To find the groupwise mean and groupwise sum at the same time, we can first convert the data frame into a data.table object and then apply the sum function and mean function for data.table object groups as shown in the below examples.Example 1Following snippet creates a sample data frame −Group

When we want to find the combinations of a vector elements, we can use combn function with size of the combination say 2 for pairs but the result gives space between the values. If we do not want to get the combinations with space then combn function will be used with paste function by collapsing the space as shown in the below examples.Check out the below examples to understand how it can be done.Example 1To find all combinations of a vector elements without space, use the snippet given below −x1