Adding Titles to xtable

Table creation is an essential component in data analysis, and Sweave is one of the most popular systems used to create tables with R. However, adding labels to a table can be challenging if you are not aware of how it works.

In this article, we will discuss how to add titles to a Sweave table created using xtable.

Background

Table creation in Sweave involves using the MakeData function followed by creating a table and then printing it. In the example given, the author used MakeData, and created two vectors (Grade3 and Grade6) that represent the students’ marks from Grade 3 and Grade 6 respectively.

However, when the author printed the table using xtable, the output did not have any labels or titles. The problem arises when you want to add a title to the table so that people can know which mark is from which grade.

Solution

The solution lies in modifying the code used to create and print the table. In this example, we will discuss two methods of adding labels to a Sweave table created using xtable.

Method 1: Modifying Row and Column Names

One way to add titles to your table is by changing the row names and column names.

library(xtable)

Grade3 <- c("A","B","B","A","B","C","C","D","A","B","C","C","C","D","B","B","D","C","C","D")
Grade6 <- c("A","A","A","B","B","B","B","B","C","C","A","C","C","C","D","D","D","D","D","D")

# Set row and column names
rownames(Cohort) <- 1:4
colnames(Cohort) <- 5:8

# Print the table with titles
print(xtable(Cohort, caption = 'My Table Title'))

In this example, we set rownames(Cohort) to 1:4 and colnames(Cohort) to 5:8. The resulting output is a table with row and column names that match the titles provided.

Method 2: Using add.to.row

However, sometimes you might want your labels to appear above the levels of each grade. In this case, you can use add.to.row which takes a list of commands as an argument.

library(xtable)

Grade3 <- c("A","B","B","A","B","C","C","D","A","B","C","C","C","D","B","B","D","C","C","D")
Grade6 <- c("A","A","A","B","B","B","B","B","C","C","A","C","C","C","D","D","D","D","D","D")

# Create a list of commands
addtorow <- list(
  pos = list(0, 0), # Position of the label
  command = c('&amp; &amp; Grade 6 &amp; \\\\\n', "Grade 3 &amp; A &amp; B &amp; C &amp; D \\\\\n")
)

# Print the table with labels
print(xtable(Cohort, caption = 'My Table Title', add.to.row = addtorow))

In this example, we create a list of commands using addtorow. The first element of the list is a vector that contains the positions where you want to place your label. We set both positions to 0 which means they will be placed above the table.

The second element is a vector that contains the commands to be executed when the labels are printed. In this case, we print two lines of text: “Grade 6” and “Grade 3 A B C D”.

Note that add.to.row can take different forms depending on what you want to achieve. You can use it to add multiple columns or even a complete row with all the labels.

Conclusion

Adding titles to your Sweave table created using xtable is straightforward and only requires modifying the row names, column names, or using add.to.row. Both methods are useful depending on what you want to achieve.

Last modified on 2024-10-20