Quoting "Zhang Weiwu" :
Jim Holtman asked me to elaborate the problem:
It is a common problem in reading sparse variable-lenght record data
file. Records are stored in file one next to another. The length of
each record is known in advance, but a lot of them records are invalid,
It is a nice surprise to wake up receiving three answers, all producing
correct results. Many thanks to all of you.
Jim Holtman solved it with amazing clarity. Gang Peng using a traditioanl
C-like pointer style and Arun with awesome tight code thanks to diff().
I am embrassed to see my mis-
HI,
May be this helps:
record.length <- read.table(text = "NR length
1 100
2 130
3 150
4 148
5 100
6 83
7 60", sep="",header = TRUE)
valida.records <- read.table(text = "NR factor
1 3
n.record <- length(record.lenths$NR)
index <- record.lenths$NR %in% valida.records$NR
tmp <- 1:n.record
ind <- tmp[index]
st <- 1
skip <- rep(0,length(ind))
for(i in 1:length(ind)){
if(st
>
> I've got two data frames, as shown below:
> (NR means Number of Record)
>
> record.lenths
>>
>
try this:
> record.length <- read.table(text = "NR length
+ 1 100
+ 2 130
+ 3 150
+ 4 148
+ 5 100
+ 683
+ 760", header = TRUE)
> valida.records <- read.table(text = " NR factor
+
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