Re: [R] About change columns and specific rows in R

Thanks for all your help. It works now. On Tue, May 23, 2017 at 1:34 AM, William Michels via R-help < r-help@r-project.org> wrote: > Hi Ivan, > > I was just writing a follow-up note as your note came in. While the > code I posted previously works fine, using which() is unnecessary. > > > DF <- re

Re: [R] About change columns and specific rows in R

Hi Ivan, I was just writing a follow-up note as your note came in. While the code I posted previously works fine, using which() is unnecessary. > DF <- read.csv("~/lily.csv") > DF$product1_1 <- NA > DF$product1_1 <- DF[DF$month == 1, "product1"]*3.1 Error in `$<-.data.frame`(`*tmp*`, "product1_1"

Re: [R] About change columns and specific rows in R

Hi, Actually, you don't need to create the column first, nor to use which: DF[DF$month==1, "product1_1"] = DF[DF$month==1, "product1"] * 3.1 The "[" is a great tool that you need to learn. In this case, you don't need to combine "[" and $: within the square brackets, the vector before the comm

Re: [R] About change columns and specific rows in R

Hi Lily, You're on the right track, but you should define a new column first (filled with NA values), then specify the precise rows and columns on both the left and right hand sides of the assignment operator that will be altered. Luckily, this is pretty easy...just remember to use which() on the

[R] About change columns and specific rows in R

Hi R users, I have a question about manipulating the dataframe. I want to create a new dataframe, and to multiply rows with different seasons for different constants. DF year month day product1 product2 product3 1981 1 1 18 5620 1981 1