[R] floodfill with matrix data
Thomas Petzoldt
thpe at hhbio.wasser.tu-dresden.de
Mon Aug 25 15:14:56 CEST 2003
Dear R users,
I'm trying to do some sort of "floodfill" or "seedfill" with data stored
within a matrix in R (usually floating numbers), where a marker value is
given to specify the limits of an area to be filled. A reduced example
may demonstrate this below. Although I wrote a simple C function for
this, it would be very helpful to find a more professional solution.
Any suggestions or code snippets are greatly appreciated.
Thomas Petzoldt
--------------------------------------------------------------------------
The problem:
## (1) Given the following matrix
z <- matrix(c(0,0,0,0,0,0,
0,1,1,1,1,0,
0,1,0,0,1,0,
0,1,1,1,1,0,
0,1,0,0,1,0,
0,1,0,1,1,0,
0,0,0,0,0,0), nrow=6, ncol=7)
image(z)
## (2) _a_procedure_is_wanted to
# "floodfill" all zeroes with 2 "outside 1"
# to give
## (3) the following result:
z <- matrix(c(2,2,2,2,2,2,
2,1,1,1,1,2,
2,1,0,0,1,2,
2,1,1,1,1,2,
2,1,2,2,1,2,
2,1,2,1,1,2,
2,2,2,2,2,2), nrow=6, ncol=7)
image(z)
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