[R-sig-Geo] Problem with execGRASS and r.mapcalculator

[Rainer M Krug]

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Hi

when using r.mapcalculator via execGRASS, a problem arises if in the
formula are no spaces, as the formula is then not enclosed in \". This
leads to a syntax eror, as in the second example. Would it be a problem
to enclose *all* strings given in \"? This would solve the problem.

See example below.

In addidion (example 3), a cut off error message is printed in R, but no
error raised in R itself - would there be a possibility, to evaluate if
an error occurred in GRASS? I remember a discussion about that, but I
don't seem to recall the outcome.

Cheers,

Rainer


# ERROR #####################################
> doGRASS(cmd="r.mapcalculator", parameter=list(amap="MASK",
bmap="MASK", formula="round(A + B)", outfile="test"), flags="overwrite")
[1] "r.mapcalculator --overwrite amap=MASK bmap=MASK formula=\"round(A +
B)\" outfile=test"

> execGRASS(cmd="r.mapcalculator", parameter=list(amap="MASK",
bmap="MASK", formula="round(A+B)", outfile="test"), flags="overwrite")
sh: Syntax error: "(" unexpected

# WORKING #####################################
> doGRASS(cmd="r.mapcalculator", parameter=list(amap="MASK",
bmap="MASK", formula="round(A+B)", outfile="test"), flags="overwrite")
[1] "r.mapcalculator --overwrite amap=MASK bmap=MASK formula=round(A+B)
outfile=test"

> execGRASS(cmd="r.mapcalculator", parameter=list(amap="MASK",
bmap="MASK", formula="round(A + B)", outfile="test"), flags="overwrite")
r.mapcalc "test" = "(round( "MASK" + "MASK" ))"

Done.
######################################

# example 2 #####################################
> execGRASS(cmd="r.mapcalculator", parameter=list(amap="MASK",
bmap="MASK", formula="round(A + B", outfile="test"), flags="overwrite")
r.mapcalc "test" = "(round( "MASK" + "MASK" )"
syntax error, unexpected $end, expecting ')'
Parse error
RROR: Calculating test. Try expert mode.
>

- -- 
Rainer M. Krug, PhD (Conservation Ecology, SUN), MSc (Conservation
Biology, UCT), Dipl. Phys. (Germany)

Centre of Excellence for Invasion Biology
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email:      Rainer at krugs.de

Skype:      RMkrug
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