Create new data frame of percentages from values of an old data frame? - sql

Question

So I want to create a new data frame adding the values of the Sometimes and Often column and dividing it by the values of the total column and multiplying it by 100 to get percentages (unless there is a function that automatically does this in R). How would I go about doing that?

Answer 1

You have added an "sql" tag to your question. Should you prefer SQL over R for reasons of experience and/or knowledge you might be interested in the fabulous sqldf package which allows you to use SQL syntax within R. You will have to download it first via install.packages("sqldf") and then you can use it as in
expl <- data.frame(sometimes = c(1, 2, 4), often = c(2, 2, 2), total =c(6, 9, 8))
library(sqldf)
sqldf("SELECT 100*(sometimes+often)/total FROM expl")

Answer 2

The far more often used way is to add a percent column to the same data.frame instead of introducing a new one. That way, all data are kept together and you do not loose the link to e. g. the week column.
One way to go about that would be the following one-liner:
expl <- data.frame(sometimes = c(1, 2, 4), often = c(2, 2, 2), total =c(6, 9, 8))
print(expl)
expl$percent = 100 * (expl$sometimes + expl$often)/expl$total
print(expl)

Answer 3

First, it looks as though Total, Sometimes, and Often are character because you have commas in them, so you would need to get rid of the commas and convert them to numeric. You can do that as follows (assuming your dataframe is called mydata):
for(i in c("Total","Sometimes","Often")) mydata[[i]] = as.numeric(gsub(",", "", mydata[[i]])
Then you can use the answer by Bernard:
mydata$percent = 100 * (mydata$Sometimes + mydata$Often)/mydata$Total

Answer 4

Another option using the tidyverse:
library(tidyverse)
newdataframe <- olddataframe %>%
mutate(percent = (Sometimes+Often)/Total*100) %>%
select(percent)
But as said before, better leave the percentage column with the other data. In that case, remove the %>% select(percent).