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Calculate Row Values
In education, we often create sum scores or means scores for different measures. And when your data is structured in a wide format (one row per participant), you will want those scores to be calculated row-wise for every individual in your data.
| stu_id | item1 | item2 | item3 | sum_score |
|---|---|---|---|---|
| 234 | 4 | 3 | 2 | 9 |
| 255 | 3 | 5 | 2 | 10 |
| 276 | 1 | 2 | 4 | 7 |
You may also want to calculate a row-wise total for something like total number of students in a school when your data is disaggregated by a category such as grade level per school.
| sch_id | grade_6 | grade_7 | grade_8 | total |
|---|---|---|---|---|
| 4578 | 120 | 113 | 142 | 375 |
| 5900 | 55 | 48 | 61 | 164 |
| 5787 | 180 | 175 | 154 | 509 |
There are several different ways to achieve this.
In the tidyverse the two most common methods of calculating row sums, means, etc. is to use:
base::rowSums() or base::rowMeans()
or
dplyr::rowwise()
There has been some debate around which function is more efficient. Some people have said that rowwise is less efficient and will slow you down because it essentially is a dplyr::group_by() for every row in your data. However, others have said that rowwise has been reinvigorated and is the preferred method now. Both work well so I say take your pick.
I also want to note, that as someone who works with a lot of .sav files and users who use SPSS, I have also included an example of how to calculate row values when your variables contain labelled NA values (as used often in SPSS). R does not recognize labelled NA (like -999 as user-defined missing value) as an NA value in rowwise calculations. Therefore I have included an example, in Calculate row sums or means, of how you may want to work with these types of variables.
- Calculate row sums or means
- Sum row occurrences of strings
- Calculate row sums of NA values
- Calculate percent agreement per pair
Main functions used in examples
| Package | Functions |
|---|---|
| base | rowSums(); rowMeans() |
| dplyr | rowwise() |
| janitor | adorn_totals() |
Other functions used in examples
| Package | Functions |
|---|---|
| dplyr | mutate(); across(); c_across(); select(); case_when(); summarise(); group_by() |
| tidyselect | starts_with(); contains() |
| base | sum();mean(); round(); ifelse(); diff() |
| labelled | na_values() |
| stringr | str_detect() |
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