There may well be neater ways to do this, but if you have only a
limited number of zeros in any run, this is probably as quick as
any. Suppose your data frame is 'dat':
> fixCol <- function(x) {
y <- x
n <- length(x)
while(any(zx <- x == 0)) {
y <- c(NA, y[-n])
x[zx] <- y[zx]
}
x
}
> dat <- transform(dat, x = fixCol(x),
y = fixCol(y), z = fixCol(z))
If you have a great number of columns to fix up like this, a more
succinct way would be something like
> dat[, 3:5] <- lapply(dat[, 3:5], fixCol)
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-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
On Behalf Of saikat sarkar
Sent: Sunday, 6 April 2008 11:05 PM
To: r-help@r-project.org
Subject: [R] how to manupute data frame with conditions fill cell with
previous value if next cell is zero
Dear R Experts,
This is the 2nd time in the chat room. Its a great place to get help
from R
experts.
I have a data frame problem, it contains thousands of data.
part of it, I am giving for explaining the problem
date day x y z
82 1989-04-28 Fri 2118.0 2418.80 33713
83 1989-05-01 Mon 0.0 2414.96 33793
84 1989-05-02 Tue 2103.1 2402.86 33955
85 1989-05-03 Wed 2105.7 2393.70 0
86 1989-05-04 Thu 2119.0 2384.90 0
87 1989-05-05 Fri 2132.8 2381.96 0
103 1989-05-29 Mon 0.0 0.00 34161
127 1989-06-30 Fri 2151.0 2440.06 32949
128 1989-07-03 Mon 2165.6 2452.77 33236
129 1989-07-04 Tue 2174.4 0 35376
130 1989-07-05 Wed 2162.9 2456.56 33310
167 1989-08-25 Fri 2397.4 2732.36 34740
168 1989-08-28 Mon 0.0 2743.36 34607
169 1989-08-29 Tue 2380.8 2726.63 34688
170 1989-08-30 Wed 2381.3 2728.15 34472
171 1989-08-31 Thu 2387.9 2737.27 34431
172 1989-09-01 Fri 2407.5 2752.09 34348
173 1989-09-04 Mon 2419.2 0.00 34484
174 1989-09-05 Tue 2426.0 2744.68 34442
175 1989-09-06 Wed 2390.8 2719.79 34271
176 1989-09-07 Thu 2415.9 2706.88 34153
177 1989-09-08 Fri 2423.9 2709.54 34116
178 1989-09-11 Mon 2400.6 2704.41 34114
179 1989-09-12 Tue 2397.6 2707.26 34333
180 1989-09-13 Wed 2401.5 2679.52 34287
181 1989-09-14 Thu 2382.0 2664.89 34402
182 1989-09-15 Fri 2366.5 2674.58 0
183 1989-09-18 Mon 2373.8 2687.50 34473
195 1989-10-04 Wed 2312.1 2771.09 35383
196 1989-10-05 Thu 2281.6 2773.56 35523
197 1989-10-06 Fri 2277.5 2785.52 35209
198 1989-10-09 Mon 2247.0 2791.41 35376
199 1989-10-10 Tue 2218.8 2785.33 0
200 1989-10-11 Wed 2218.8 2773.36 35240
In this data frame, I need to replace cells which is zero with previous
value.
For example
82 1989-04-28 Fri 2118.0 2418.80 33713
83 1989-05-01 Mon 0.0 2414.96 33793
in 2nd line 0.0 should be replaced by 2118.0
Another Example
84 1989-05-02 Tue 2103.1 2402.86 33955
85 1989-05-03 Wed 2105.7 2393.70 0
86 1989-05-04 Thu 2119.0 2384.90 0
87 1989-05-05 Fri 2132.8 2381.96 0
3 lines filled by 33955 value.
Another example
198 1989-10-09 Mon 2247.0 2791.41 35376
199 1989-10-10 Tue 2218.8 2785.33 0
200 1989-10-11 Wed 2218.8 2773.36 35240
in 2nd line filled by zero should be replaced by value 35376
Please help me.
Thanking you
saikat
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