Subtracting elements of data.frame
On 2011-01-25 01:20, Vincy Pyne wrote:
Dear R helpers I have a dataframe as df = data.frame(x = c(1, 14, 3, 21, 11), y = c(102, 500, 40, 101, 189))
df
x y 1 1 102 2 14 500 3 3 40 4 21 101 5 11 189 # Actually I am having dataframe having multiple columns. I am just giving an example. I need to subtract all the rows of df by the first row of df i.e. I need to subtract each element of 'x' column by 1. Likewise I need to subtract all elements of column 'y' by 11. Thus I need an output like
df_new
x y 1 0 0 2 13 398 3 2 -62 4 20 -1 5 10 87 As I had mentioned above, I have number of columns in reality and thus I can't use the command say df_new = data.frame(x = df$x-df$x[1], y = df$y-df$y[1]) Kindly guide
You've already had good simple solutions. Here's one more,
using the plyr package:
require(plyr)
df_new <- colwise(.fun = function(x) {x - x[1]})(df)
plyr is very handy for all sorts of data manipulations.
Peter Ehlers
Thanking you all in advance Regards Vincy [[alternative HTML version deleted]]