How To Use RowSums in R (With Examples)

Sometimes, in data science, it is necessary, to sum up, the rose set. In most programming languages, this would be a tedious task, particularly with large data sets. Here is a case where R comes to the rescue. It has a formula that can do the job with a single line of code

The RowSums Function.

Rowsums in r is based on the rowSums function what is the format of rowSums(x) and returns the sums of each row in the data set. There are some additional parameters that can be added, the most useful of which is the logical parameter of na.rm which tells the function whether to skip N/A values

# data for rowsums in R examples
> a = c(1:5)
> b = c(1:5*2)
> c = c(1:5*3)
> d = c(1:5/2)
> e = c(1:5/4)
> x = data.frame(a,b,c,d,e)
> x
  a  b  c   d    e
1 1  2  3 0.5 0.25
2 2  4  6 1.0 0.50
3 3  6  9 1.5 0.75
4 4  8 12 2.0 1.00
5 5 10 15 2.5 1.25

# rowsum in R example / results
> rowSums(x)
[1]  6.75 13.50 20.25 27.00 33.75

If you manually add each row together, you will see that they add up do the numbers provided by the rowsSums formula in one simple step.

Applications of The RowSums Function.

The applications for rowsums in r are numerous, being able to easily add up all the rows in a data set provides a lot of useful information. In the example below, we have the number of phones in different parts of the world in different years, by adding up, the rows you can get the total number of phones worldwide for that year.

# rowsums in R - phone data
> head(WorldPhones)
      N.Amer Europe Asia S.Amer Oceania Africa Mid.Amer
 1951  45939  21574 2876   1815    1646     89      555
 1956  60423  29990 4708   2568    2366   1411      733
 1957  64721  32510 5230   2695    2526   1546      773
 1958  68484  35218 6662   2845    2691   1663      836
 1959  71799  37598 6856   3000    2868   1769      911
 1960  76036  40341 8220   3145    3054   1905     1008
# rowsums in R example / results
 > rowSums(WorldPhones)
 1951   1956   1957   1958   1959   1960   1961 
 74494 102199 110001 118399 124801 133709 141700 

Summing up the rows of data is an extremely useful tool and one which is simple to use. This single-function returns the sums for all the rows of the data set being worked on. This one simple tool does so much work that it is one of the examples of the power of R.

Potential Errors

There are a couple of potential errors you can throw with this function. For example, the R rowsums() function isn’t very tolerant of missing or non-numeric data. You can easily generate lovely errors such as…

error in rowsums(x, na.rm = true) : ‘x’ must be numeric

Should this lovely fail-whale appear, the cause is simple enough. Check the data you’ve fed into your process. Something in there isn’t numeric and the rowsums function throws a little tantrum to communicate that you. My best suggestion is to filter the missing or incorrect data point from your data and proceed from there.

You may also get:

error in rowsums: ‘x’ must be an array of at least two dimensions

Which occurs when you feed a vector (single dimensional series of values) into a function which expects to look at an array.

Related Functions & Broader Usage

There are several functions designed to help you calculate the total and average value of columns and rows in R. In addition to rowmeans in r, this family of functions includes colmeans, rowsum, and colsum. Here’s some specifics on where you use them…

  • Colmeans – calculate mean of multiple columns in r .
  • Colsums – how do i sum each column in r…
  • Rowsums – sum specific rows in r

These functions are extremely useful when you’re doing advanced matrix manipulation or implementing a statistical function in R. These form the building blocks of many basic statistical operations and linear algebra procedures. This is why you sometimes see an error message from this cluster of functions show up as part of a higher level package.

In the event you need them, there are also functions for RowMedians (solves for the median of a row in R) and RowSD (solves for the standard deviation of a row in R). Given the existence of the above, be sure to do a quick search of the various R packages if you need anything more exotic – since it most likely exists…

If you are looking to solve for rowmeans or rowsums by group, check out the aggregate function (one of the items we addressed in our article about descriptive statistics).

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