rocket at google.com
2008-May-30 15:40 UTC
[Rd] scoping problem when calling lm(precomputed formula, weights) from function (PR#11540)
I've run into a scoping problem in R.
I'm calling a function that
* creates a formula
* calculates a weight vector
* calls lm with that formula and weights
This fails.
Here's a simplified reproduce example:
# f works, g doesn't, h is a workaround
rm(w)
data <- data.frame(y=runif(20), x=runif(20), z=runif(20))
f <- function(k){
w <- data$z^k
coef(lm(y~x, data = data, weights = w))
}
g <- function(k){
w <- data$z^k
Formula <- parse(text="y~x")[[1]]
coef(lm(Formula, data = data, weights = w))
}
h <- function(k){
w <- data$z^k
Formula <- parse(text="y~x")[[1]]
# Following line fails due to scoping bug. Use workaround.
# coef(lm(Formula, data = data, weights = w))
Call <- paste("coef(lm(", deparse(Formula), ", data=data,
weights=w))")
eval(parse(text=Call)[[1]])
}
> f(2)
(Intercept) x
0.7452512 -0.3413998 > g(2)
Error in eval(expr, envir, enclos) : object "w" not
found> traceback()
9: eval(expr, envir, enclos)
8: eval(extras, data, env)
7: model.frame.default(formula = Formula, data = data, weights = w,
drop.unused.levels = TRUE)
6: model.frame(formula = Formula, data = data, weights = w, drop.unused.levels =
TRUE)
5: eval(expr, envir, enclos)
4: eval(mf, parent.frame())
3: lm(Formula, data = data, weights = w)
2: coef(lm(Formula, data = data, weights = w))
1: g(2)> h(2)
(Intercept) x
0.7452512 -0.3413998
--please do not edit the information below--
Version:
platform = i486-pc-linux-gnu
arch = i486
os = linux-gnu
system = i486, linux-gnu
status =
major = 2
minor = 7.0
year = 2008
month = 04
day = 22
svn rev = 45424
language = R
version.string = R version 2.7.0 (2008-04-22)
Locale:
LC_CTYPE=en_US;LC_NUMERIC=C;LC_TIME=C;LC_COLLATE=C;LC_MONETARY=C;LC_MESSAGES=en_US;LC_PAPER=en_US;LC_NAME=C;LC_ADDRESS=C;LC_TELEPHONE=C;LC_MEASUREMENT=en_US;LC_IDENTIFICATION=C
Search Path:
.GlobalEnv, package:stats, package:graphics, package:grDevices, package:utils,
package:datasets, package:showStructure, package:Rcode, package:splus2R,
package:methods, Autoloads, package:base
Gabor Grothendieck
2008-May-30 17:56 UTC
[Rd] scoping problem when calling lm(precomputed formula, weights) from function (PR#11540)
Try replacing the last line in g with: lmout <- do.call(lm, list(Formula, data = data, weights = w)) coef(lmout) or replace w with environment()$w thereby explicitly telling it where to look. On Fri, May 30, 2008 at 11:40 AM, <rocket at google.com> wrote:> I've run into a scoping problem in R. > I'm calling a function that > * creates a formula > * calculates a weight vector > * calls lm with that formula and weights > This fails. > > Here's a simplified reproduce example: > # f works, g doesn't, h is a workaround > rm(w) > data <- data.frame(y=runif(20), x=runif(20), z=runif(20)) > f <- function(k){ > w <- data$z^k > coef(lm(y~x, data = data, weights = w)) > } > g <- function(k){ > w <- data$z^k > Formula <- parse(text="y~x")[[1]] > coef(lm(Formula, data = data, weights = w)) > } > h <- function(k){ > w <- data$z^k > Formula <- parse(text="y~x")[[1]] > # Following line fails due to scoping bug. Use workaround. > # coef(lm(Formula, data = data, weights = w)) > Call <- paste("coef(lm(", deparse(Formula), ", data=data, weights=w))") > eval(parse(text=Call)[[1]]) > } > > >> f(2) > (Intercept) x > 0.7452512 -0.3413998 >> g(2) > Error in eval(expr, envir, enclos) : object "w" not found >> traceback() > 9: eval(expr, envir, enclos) > 8: eval(extras, data, env) > 7: model.frame.default(formula = Formula, data = data, weights = w, > drop.unused.levels = TRUE) > 6: model.frame(formula = Formula, data = data, weights = w, drop.unused.levels = TRUE) > 5: eval(expr, envir, enclos) > 4: eval(mf, parent.frame()) > 3: lm(Formula, data = data, weights = w) > 2: coef(lm(Formula, data = data, weights = w)) > 1: g(2) >> h(2) > (Intercept) x > 0.7452512 -0.3413998 > > > > --please do not edit the information below-- > > Version: > platform = i486-pc-linux-gnu > arch = i486 > os = linux-gnu > system = i486, linux-gnu > status > major = 2 > minor = 7.0 > year = 2008 > month = 04 > day = 22 > svn rev = 45424 > language = R > version.string = R version 2.7.0 (2008-04-22) > > Locale: > LC_CTYPE=en_US;LC_NUMERIC=C;LC_TIME=C;LC_COLLATE=C;LC_MONETARY=C;LC_MESSAGES=en_US;LC_PAPER=en_US;LC_NAME=C;LC_ADDRESS=C;LC_TELEPHONE=C;LC_MEASUREMENT=en_US;LC_IDENTIFICATION=C > > Search Path: > .GlobalEnv, package:stats, package:graphics, package:grDevices, package:utils, package:datasets, package:showStructure, package:Rcode, package:splus2R, package:methods, Autoloads, package:base > > ______________________________________________ > R-devel at r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-devel >
Duncan Murdoch
2008-May-30 18:22 UTC
[Rd] scoping problem when calling lm(precomputed formula, weights) from function (PR#11540)
On 5/30/2008 11:40 AM, rocket at google.com wrote:> I've run into a scoping problem in R.No, in your use of it.> I'm calling a function that > * creates a formula... incorrectly.> * calculates a weight vector > * calls lm with that formula and weights > This fails. > > Here's a simplified reproduce example: > # f works, g doesn't, h is a workaround > rm(w) > data <- data.frame(y=runif(20), x=runif(20), z=runif(20)) > f <- function(k){ > w <- data$z^k > coef(lm(y~x, data = data, weights = w)) > } > g <- function(k){ > w <- data$z^k > Formula <- parse(text="y~x")[[1]]If this were simply Formula <- y ~ x it would work, because then the formula would get the evaluation environment attached. I assume your real case builds up a formula in text and then parses it, in which case you'll have to evaluate the formula to get the environment set: > g function (k) { w <- data$z^k Formula <- eval(parse(text = "y ~ x")) coef(lm(Formula, data = data, weights = w)) } > g(2) (Intercept) x 0.7777419 -0.7023185 In more complicated cases, you may need to explicitly set the environment of the constructed formula, using e.g. environment(Formula) <- environment() Duncan Murdoch> coef(lm(Formula, data = data, weights = w)) > } > h <- function(k){ > w <- data$z^k > Formula <- parse(text="y~x")[[1]] > # Following line fails due to scoping bug. Use workaround. > # coef(lm(Formula, data = data, weights = w)) > Call <- paste("coef(lm(", deparse(Formula), ", data=data, weights=w))") > eval(parse(text=Call)[[1]]) > } > > >> f(2) > (Intercept) x > 0.7452512 -0.3413998 >> g(2) > Error in eval(expr, envir, enclos) : object "w" not found >> traceback() > 9: eval(expr, envir, enclos) > 8: eval(extras, data, env) > 7: model.frame.default(formula = Formula, data = data, weights = w, > drop.unused.levels = TRUE) > 6: model.frame(formula = Formula, data = data, weights = w, drop.unused.levels = TRUE) > 5: eval(expr, envir, enclos) > 4: eval(mf, parent.frame()) > 3: lm(Formula, data = data, weights = w) > 2: coef(lm(Formula, data = data, weights = w)) > 1: g(2) >> h(2) > (Intercept) x > 0.7452512 -0.3413998 > > > > --please do not edit the information below-- > > Version: > platform = i486-pc-linux-gnu > arch = i486 > os = linux-gnu > system = i486, linux-gnu > status = > major = 2 > minor = 7.0 > year = 2008 > month = 04 > day = 22 > svn rev = 45424 > language = R > version.string = R version 2.7.0 (2008-04-22) > > Locale: > LC_CTYPE=en_US;LC_NUMERIC=C;LC_TIME=C;LC_COLLATE=C;LC_MONETARY=C;LC_MESSAGES=en_US;LC_PAPER=en_US;LC_NAME=C;LC_ADDRESS=C;LC_TELEPHONE=C;LC_MEASUREMENT=en_US;LC_IDENTIFICATION=C > > Search Path: > .GlobalEnv, package:stats, package:graphics, package:grDevices, package:utils, package:datasets, package:showStructure, package:Rcode, package:splus2R, package:methods, Autoloads, package:base > > ______________________________________________ > R-devel at r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-devel