# [R] Nested functions

John Wiedenhoeft wiedenhoeft at gmx.net
Mon Jul 17 22:34:34 CEST 2006

```Hi there,

I'm having myself a hard time writing an algorithm for finding patterns
within a given melody. In a vector I'd like to find ALL sequences that
occur at least twice, without having to check all possible patterns via
pattern matching.

I finally found a solution in a style that I'm used from C, i.e. calling
one function from within another. GNU R doesn't seem to like that, it
complains about too deep nesting and infinite recursion (I can't see
that...). I've tried options(expressions=500000), but even then the
variable a doesn't make it over 2 (my vectors have about 100-300
elements).

I'm not a software engineer, so I guess that algo is rather badly
designed. I'd appreciate any help on how to make it suitable for R, or
about alternative approaches (I guess something like this must be used
in bioinformatics, but I didn't find it implemented in R. Any hints are
welcome ;-) )

John

CODECODCODECODECODECODECODECODECODECODECODECODECODECODECODECODE

antiphonar <- function(v)
{
a <- 1;
b <- 2;
n <- length(v);
alessn(a, b, n, v, x);
}

alessn <- function(a, b, n, v, x)
{
if(a<n)
{vavb(a, b, n, v, x);}
else{print("That's all, folks ;-)");}
}

vavb <- function(a, b, n, v, x)
{
if(v[a]==v[b])
{
x <- 1;
while( v[a+x] == v[b+x] && b+x<n)
{x <- x+1;}
m <- 0;
for(k in 0:(x-1))
{m <- v[a+k]*10^(x-1-k)+m;}
p <- c(x, a, b, m);
print(p);
baba(a, b, n, v, x);
}
else baba(a, b, n, v, x);
}

baba <- function(a, b, n, v, x)
{
b <- b+1;
if(b<=n)
{vavb(a, b, n, v, x);}
else
{
a <- a+1;
b <- a+1;
alessn(a, b, n, v, x);
}
}

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```