How to Put margins on tables or arrays in R
How to Put margins on tables or arrays in R, We’ll show you how to use the addmargins function in R to add margins to tables or arrays.
The tutorial will include two examples of using the addmargins function to annotate margin values on table objects.
Let’s get this party started:
How to Put margins on tables or arrays in R
For this R tutorial, we’ll start with the data below:
data <- data.frame(x1 = c(LETTERS[1:3], "B", "B", "C") x2 = letters[1:2]) data
x1 x2 1 A a 2 B b 3 C a 4 B b 5 B a 6 C b
Examine the preceding table. It shows that the example data frame has six rows and two variables.
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Based on these data, we can then create a table object (i.e. a contingency table).
tab <- table(data) tab
x2 x1 a b A 1 0 B 1 2 C 1 1
The preceding RStudio console output shows our table without margins.
Example 1: Assign Sum Margins to a Contingency Table Using the function addmargins()
Example 1, Will show how to use the addmargins function to add the sum of each row and column to a table’s margins.
Consider the R code below:
tab_sum <- addmargins(tab, FUN = sum) tab_sum
x2 x1 a b sum A 1 0 1 B 1 2 3 C 1 1 2 sum 3 3 6
As you can see, we have annotated another row and column with our data’s sum margins.
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Example 2: Assign Mean Margins to a Contingency Table Using the function addmargins()
We used the sum function in Example 1 to add margins to our contingency table.
However, other functions within the addmargins command can be used.
The R code below demonstrates how to annotate mean values to a table object:
tab_mean <- addmargins(tab, FUN = mean) tab_mean
x2 x1 a b mean A 1.0 0.0 0.5 B 1.0 2.0 1.5 C 1.0 1.0 1.0 mean 1.0 1.0 1.0
The previous table has the same structure as Example 1. However, instead of sum margins, we have included mean margins this time.
