I would like to use R to filter climate data. I am looking ideally for a package to allow me to use the Lanczos filter (I can actually do it in Python and NCL but would like to do the same in R). If there is no available package for that, it would be great also to be provided with the algorithm used to calculate the Lanczos weights so that I can write a function by myself.
Cheers
http://lmgtfy.com/?q=Lanczos+r
Use propack from svd
I managed to write a code myself in case someone is interested.
This is the code for that:
lanczos_weights=function(N=50,dt=1,highper=90,lowper=10,filter="lowpass"){
n=-N:N
W_low=ifelse(n!=0,(sin(2*pi*dt*n/lowper)*sin(pi*n/N))/(pi*n*pi*n/N),2*pi*dt/lowper)
W_high=ifelse(n!=0,(sin(2*pi*dt*n/highper)*sin(pi*n/N))/(pi*n*pi*n/N),2*pi*dt/highper)
W_high[ceiling(length(W_high)/2)]=1-W_high[ceiling(length(W_high)/2)];W_high[-ceiling(length(W_high)/2)]=-W_high[-ceiling(length(W_high)/2)]
W_band=W_low-W_high
if(filter=="lowpass"){return(W_low)}else if(filter=="highpass"){return(W_high)} else if (filter=="bandpass"){return(W_band)}else {print("Error: please specify the filter type")}
}
- Badges
- Science topic
- Similar topics
- Computer Science and Engineering
- Programming Languages
- Python