I have two data-frame with unequal number of rows. But i need to smooth the data in both the data frames and plot them together. I can smooth each dataframe with lowess/loess. However, when i try to plot the lines for both the data-frames together, i usually get error "unequal number of rows". I found a way around this by using spline. I want to know if the following would be valid:
tmp1 <- spline( lowess( df1[,1], df[,2] ), n = 20 )
tmp2 <- spline( lowess( df2[,1], df2[,2] ), n = 20 )
plot( tmp1[,1], tmp1[,2], type="l" )
lines( tmp2[,1], tmp2[,2], col="red" )
I want to know whether it is "statistically" valid to plot spline of a lowess object its its representation, because I want to limit number of data-points. This is specifically for case where the lowess on to different series contain unequal number of points?
It would have worked if you (and I) had remembered that splines does not return an object that can be addressed as row and columns. It returns a two element list of vectors. So you need to fix the spelling of the second "df" and use "[[":
# test data
df1 <- data.frame(x=rnorm(100), y=rpois(100, lambda=.5))
df2 <- data.frame(x=rnorm(200), y=rpois(200, lambda=.5))
tmp1 <- spline( lowess( df1[,1], df1[,2] ), n = 20 )
tmp2 <- spline( lowess( df2[,1], df2[,2] ), n = 20 )
plot( tmp1[[1]], tmp1[[2]], type="l" )
lines( tmp2[[1]], tmp2[[2]], col="red" )
That exmple might not have been a good one to get started with, since the ylim needs to be expanded to see any of the points:
plot( tmp1[[1]], tmp1[[2]], type="l", ylim=c(0,4) )
lines( tmp2[[1]], tmp2[[2]], col="red" )
points(jitter(df2[[1]]), df2[[2]], cex=0.3, col="blue")
points(jitter( df1[[1]]), df1[[2]], cex=0.3, col="red")