Hello! I have a data frame where the first column contains dates, the second one names and the other two earnings and costs. I want to make a for loop that will calculate the difference between earnings and costs for every name and every date. I have managed to do it for every name but when I try to expand it for every date I am not able to do it. In my loop I assume that i is the date and k is the name so the difference will be for example earnings [i,k] - costs [i,k] but I get the message that there is something wrong with the dimensions.
I wouldn't think to use a loop for this . r is vectorised language.
in base R to find the difference between Petal.Length and Petal.Width for each observation in iris
iris$diff <- iris$Petal.Length - iris$Petal.Width
iris <- mutate(iris, diff = Petal.Length - Petal.Width)
In future, please try to provide sample data in an easy-to-copy format (as I have done in the code below). This makes it much easier for others to help you.
As nirgrahamuk pointed out, R is vectorized so you don't need loops for these kind of operations. You can directly assign the result of the computation to a new variable.
df <- data.frame(stringsAsFactors = FALSE, date = c(as.Date("2020-07-01"), as.Date("2020-07-02")), name = c("John", "Mary"), earnings = c(1500, 2000), cost = c(1250, 1500)) df$difference <- df$earnings - df$cost df #> date name earnings cost difference #> 1 2020-07-01 John 1500 1250 250 #> 2 2020-07-02 Mary 2000 1500 500
Created on 2020-07-31 by the reprex package (v0.3.0)
Thank you! My issue was that for a particular date I had many names which were the same so the difference could not be calculated that easily however now everything works ok!
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