univariate time series.

order of moving average.

specifies whether result should be centered (default), left-aligned or right-aligned.

character string indicating how the values at the beginning and the end (of the data) should be treated.

"keep"

keeps the first and last k2 values at both ends, where k2 is the half-bandwidth k2 = k %/% 2, i.e., y[j] = x[j] for j = 1,..,k2 and (n-k2+1),..,n;

"constant"

fill the ends with first and last calculated value in output array (out[1:k2] = out[k2+1])

"NA"

the default, leaves the values to NA, as they are returned by filter.