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rmh@temple.edu

2004-Nov-28 05:36 UTC

[Rd] Is this a bug in the parser? (PR#7395)

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<<insert bug report here>>
Is this a bug in the parser?
Specifically, the trace lines

Browse[1]> x
[[1]]
[1] "factor(-(rowpos <= 2) + (rowpos >= 6), labels =
c(\"1:2\", \"3:5\", "
[2] "    ~\"6:8\"))"

suggest that a single statement was arbitrarily cut into two pieces, neither
of which makes syntactic sense, when the string was too long.

The comparable line with shorter variable names is

Browse[1]> x
[[1]]
[1] "factor(-(r <= 2) + (r >= 6), labels = c(\"1:2\",
\"3:5\", \"6:8\"))"


I am using rw2001
## Code to duplicate the problem:


options()$width
library(lattice) 
data(OrchardSprays) 
OrchardSprays$r <- OrchardSprays$rowpos

xyplot(decrease ~ treatment |
       factor(-(rowpos<=2)+(rowpos>=6),
labels=c("1:2","3:5","6:8")),
       data=OrchardSprays)

xyplot(decrease ~ treatment |
       factor(-(r<=2)+(r>=6),
labels=c("1:2","3:5","6:8")),
       data=OrchardSprays)

trace("names<-.default", exit=browser)

xyplot(decrease ~ treatment |
       factor(-(rowpos<=2)+(rowpos>=6),
labels=c("1:2","3:5","6:8")),
       data=OrchardSprays)

xyplot(decrease ~ treatment |
       factor(-(r<=2)+(r>=6),
labels=c("1:2","3:5","6:8")),
       data=OrchardSprays)



## transcript that shows the problem
##
## My mailer folds lines at 100 characters, I have several "Error",
## "Tracing", and "Called" lines that run out to 142.
> options()$width
[1] 80> library(lattice) 
> data(OrchardSprays) 
> OrchardSprays$r <- OrchardSprays$rowpos
> xyplot(decrease ~ treatment |+        factor(-(rowpos<=2)+(rowpos>=6),
labels=c("1:2","3:5","6:8")),
+        data=OrchardSprays)
Error in "names<-.default"(`*tmp*`, value = c("factor(-(rowpos
<= 2) + (rowpos >= 6), labels = c
(\"1:2\", \"3:5\", ",  : 
	names attribute [2] must be the same length as the vector
[1]> xyplot(decrease ~ treatment |+        factor(-(r<=2)+(r>=6),
labels=c("1:2","3:5","6:8")),
+        data=OrchardSprays)> trace("names<-.default", exit=browser)Tracing function "names<-.default" in package "base" 
[1] "names<-.default"> xyplot(decrease ~ treatment |+        factor(-(rowpos<=2)+(rowpos>=6),
labels=c("1:2","3:5","6:8")),
+        data=OrchardSprays)
Tracing "names<-.default"(`*tmp*`, value = NULL) on exit 
Called from: "names<-.default"(`*tmp*`, value = NULL)
Browse[1]> ls()
[1] "value" "x"    
Browse[1]> value
NULL
Browse[1]> x
[[1]]
[1] "factor(-(rowpos <= 2) + (rowpos >= 6), labels =
c(\"1:2\", \"3:5\", "
[2] "    ~\"6:8\"))"

Browse[1]> c
Tracing "names<-.default"(`*tmp*`, value = NULL) on exit 
Called from: "names<-.default"(`*tmp*`, value = NULL)
Browse[1]> c
Error in "names<-.default"(`*tmp*`, value = c("factor(-(rowpos
<= 2) + (rowpos >= 6), labels = c
(\"1:2\", \"3:5\", ",  : 
	names attribute [2] must be the same length as the vector [1]
Tracing "names<-.default"(`*tmp*`, value =
structure(c("factor(-(rowpos <= 2) + (rowpos >= 6),
labels = c(\"1:2\", \"3:5\", ",  .... on exit 
Called from: "names<-.default"(`*tmp*`, value =
c("factor(-(rowpos <= 2) + (rowpos >= 6), labels =
c(\"1:2\", \"3:5\", ", 
"    ~\"6:8\"))"))
Browse[1]> c> xyplot(decrease ~ treatment |+        factor(-(r<=2)+(r>=6),
labels=c("1:2","3:5","6:8")),
+        data=OrchardSprays)
Tracing "names<-.default"(`*tmp*`, value = NULL) on exit 
Called from: "names<-.default"(`*tmp*`, value = NULL)
Browse[1]> ls()
[1] "value" "x"    
Browse[1]> value
NULL
Browse[1]> x
[[1]]
[1] "factor(-(r <= 2) + (r >= 6), labels = c(\"1:2\",
\"3:5\", \"6:8\"))"

Browse[1]> c
Tracing "names<-.default"(`*tmp*`, value = NULL) on exit 
Called from: "names<-.default"(`*tmp*`, value = NULL)
Browse[1]> c
Tracing "names<-.default"(`*tmp*`, value = "factor(-(r <=
2) + (r >= 6), labels = c(\"1:2\", \"3:5
\", \"6:8\"))") on exit 
Called from: "names<-.default"(`*tmp*`, value = "factor(-(r
<= 2) + (r >= 6), labels = c(\"1:2\",
\"3:5\", \"6:8\"))")
Browse[1]> c
Tracing "names<-.default"(`*tmp*`, value = NULL) on exit 
Called from: "names<-.default"(`*tmp*`, value = NULL)
Browse[1]> c
Tracing "names<-.default"(`*tmp*`, value = NULL) on exit 
Called from: "names<-.default"(`*tmp*`, value = NULL)
Browse[1]> c
Tracing "names<-.default"(`*tmp*`, value = NULL) on exit 
Called from: "names<-.default"(`*tmp*`, value = NULL)
Browse[1]> c
Tracing "names<-.default"(`*tmp*`, value = NULL) on exit 
Called from: "names<-.default"(`*tmp*`, value = NULL)
Browse[1]> c
Tracing "names<-.default"(`*tmp*`, value = NULL) on exit 
Called from: "names<-.default"(`*tmp*`, value = NULL)
Browse[1]> c
Tracing "names<-.default"(`*tmp*`, value = NULL) on exit 
Called from: "names<-.default"(`*tmp*`, value = NULL)
Browse[1]> c
Tracing "names<-.default"(`*tmp*`, value = NULL) on exit 
Called from: "names<-.default"(`*tmp*`, value = NULL)
Browse[1]> Q> 


--please do not edit the information below--

Version:
 platform = i386-pc-mingw32
 arch = i386
 os = mingw32
 system = i386, mingw32
 status = 
 major = 2
 minor = 0.1
 year = 2004
 month = 11
 day = 15
 language = R

Windows XP Home Edition (build 2600) Service Pack 2.0

Search Path:
 .GlobalEnv, package:methods, package:stats, package:utils, package:datasets, 
file:c:/HOME/rmh/hh/splus.library/HH/.RData, package:multcomp, package:mvtnorm,
package:abind,
package:graphics, package:lattice, package:grid, package:grDevices, Autoloads,
package:base

Peter Dalgaard

2004-Nov-28 12:15 UTC

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[Rd] Is this a bug in the parser? (PR#7395)

rmh@temple.edu writes:
> # Your mailer is set to "none" (default on Windows),
> # hence we cannot send the bug report directly from R.
> # Please copy the bug report (after finishing it) to
> # your favorite email program and send it to
> #
> #       r-bugs@r-project.org
> #
> ######################################################
> 
> 
> 
> <<insert bug report here>>
> Is this a bug in the parser?
No (how could it be? If anything, this has to do with _de_parsing).
It's a bug (two, actually) in lattice, which has a maintainer....

Inside  latticeParseFormula

    parseCond <- function(model) {
        model <- eval(parse(text = paste("~",
deparse(model))))[[2]]
        model.vars <- list()
        ....

and later on in the same function

    names(ans$condition) <- sapply(modelRHS.vars, deparse)

both of which whill get you in trouble if deparse needs multiple
lines. Notice that paste("~", deparse(model)) will prepend a
"~" to
_every_ line, where only the first was intended, so you could have
gotten a parse error there and then.

The first bug is the sort of construct that I have been warning
people about repeatedly; computing on the language by going through
the textual representation as in parse(...deparse(...)) is almost
always wrong. In this particular case, I think the code is equivalent
to

  model <- substitute(~ m, list(m = model))

(minus the bug, of course). Bug #2 is probably just that you need to
take only the first line of deparse(), since you wouldn't want or need
the fully deparsed object for a name.
-- 
   O__  ---- Peter Dalgaard             Blegdamsvej 3  
  c/ /'_ --- Dept. of Biostatistics     2200 Cph. N   
 (*) \(*) -- University of Copenhagen   Denmark      Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard@biostat.ku.dk)             FAX: (+45) 35327907

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