z <- ts(rnorm(100), start=c(1982,1), frequency=12)
Dz <- tframed(diff(z), tfTruncate(tframe(z), start=2))
tframe(Dz)
IDz <- tframed(cumsum(c(0, Dz)), tfExpand(tframe(Dz), add.start=1))
tframe(IDz)
tframe(tfTruncate(z, start=5))
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