Hello,
Assuming that 'd' is your original data.frame and that you've set entire
rows to NA, try this
d$leak_num <- NA
ix <- !is.na(d[, 1]) # any column will do, entire row is NA
## alternative, if other rows may have NAs, due to something else
#ix <- apply(d, 1, function(x) all(!is.na(x)))
r <- rle(ix)
v <- cumsum(r$values)
d$leak_num[ix] <- rep(v[r$values], r$lengths[r$values])
d
Hope this helps,
Rui Barradas
Em 24-05-2012 11:00, Max Brondfield <mbro...@post.harvard.edu> escreveu:
Date: Wed, 23 May 2012 16:42:02 -0400
From: Max Brondfield<mbro...@post.harvard.edu>
To:r-help@r-project.org
Subject: [R] Using NA as a break point for indicator variable?
Message-ID:
<cadu+jdpcjuhztxxrsxyqvjaemw_n0ilbl6zjjhzc-rsbcmn...@mail.gmail.com>
Content-Type: text/plain
Hi all,
I am working with a spatial data set for which I am only interested in high
concentration values ("leaks"). The low values (< 90th percentile) have
already been turned into NA's, leaving me with a matrix like this:
< CH4_leak
lon lat CH4
1 -71.11954 42.35068 2.595834
2 -71.11954 42.35068 2.595688
3 NA NA NA
4 NA NA NA
5 NA NA NA
6 -71.11948 42.35068 2.435762
7 -71.11948 42.35068 2.491003
8 NA NA NA
9 -71.11930 42.35068 2.464475
10 -71.11932 42.35068 2.470865
Every time an NA comes up, it means the "leak" is gone, and the next valid
value would represent a different leak (at a different location). My goal
is to tag all of the remaining values with an indicator variable to
spatially distinguish the leaks. I am envisioning a simple numeric
indicator such as:
lon lat CH4 leak_num
1 -71.11954 42.35068 2.595834 1
2 -71.11954 42.35068 2.595688 1
3 NA NA NA NA
4 NA NA NA NA
5 NA NA NA NA
6 -71.11948 42.35068 2.435762 2
7 -71.11948 42.35068 2.491003 2
8 NA NA NA NA
9 -71.11930 42.35068 2.064475 3
10 -71.11932 42.35068 2.070865 3
Does anyone have any thoughts on how to code this, perhaps using the NA
values as a "break point"? The data set is far too large to do this
manually, and I must admit I'm completely at a loss. Any help would be much
appreciated! Best,
Max
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