How to sum a variable by group?

Question

Let's say I have two columns of data. The first contains categories such as "First", "Second", "Third", etc. The second has numbers which represent the number of times I saw "First".For example: Category Frequency First 10 First 15 First 5 Second 2 Third 14 Third 20 Second 3I want to sort the data by Category and sum the Frequencies: Category Frequency First 30 Second 5 Third 34How would I do this in R?

Answer 1

You will need to use a package called Tidyverse. The main functions you need are group_by and summarize. I don't know the names of your data sets, so i will use the name "data" to refer to your datatable, "category" to refer to the column heading of your categories, and "count" to refer to the counts that you have.

The following code also uses something called "pipes". Pipes allow for you to run multiple connected functions without having to write the name of the data-table in each line.

If you have used the name conventions I state below, your code should look something like this:

data2<-data%>%

group_by(category)%>%

summarize(sum=sum(count))