Re: [R] Passing formula as parameter to `lm` within `sapply` causes error [BUG?]

Tue, 30 Apr 2019 15:38:45 -0700 

On 30/04/2019 11:24 a.m., Jens Heumann wrote:

Hi,

`lm` won't take formula as a parameter when it is within a `sapply`; see
example below. Please, could anyone either point me to a syntax error or
confirm that this might be a bug?
I haven't looked carefully at your example. From a quick glance, however, I'd suspect that the issue is with the formula. Formulas have attached environments, where they look up variables in them that aren't in the data argument to lm(). In your code it's not obvious to me what environment would be attached, but I suspect it's the caller of sapply, not the environment that sapply creates for a particular value of its argument. I think this because of a rule that is supposed to be followed in R:
Formulas get the environment where they were created attached to them. That would be your global environment.
R is flexible, so functions don't have to follow this rule, but it causes lots of confusion when they don't. 

Duncan Murdoch




Best,
Jens

[Disclaimer: This is my first post here, following advice of how to
proceed with possible bugs from here: https://www.r-project.org/bugs.html]


SUMMARY

While `lm` alone accepts formula parameter `FO` well, the same within a
`sapply` causes an error. When putting everything as parameter but
formula `FO`, it's still working, though. All parameters work fine
within a similar `for` loop.


MCVE (see data / R-version at bottom)

  > summary(lm(y ~ x, df1, df1[["z"]] == 1, df1[["w"]]))$coef[1, ]
    Estimate Std. Error    t value   Pr(>|t|)
   1.6269038  0.9042738  1.7991275  0.3229600
  > summary(lm(FO, data, data[[st]] == st1, data[[ws]]))$coef[1, ]
    Estimate Std. Error    t value   Pr(>|t|)
   1.6269038  0.9042738  1.7991275  0.3229600
  > sapply(unique(df1$z), function(s)
+   summary(lm(y ~ x, df1, df1[["z"]] == s, df1[[ws]]))$coef[1, ])
                  [,1]       [,2]         [,3]
Estimate   1.6269038 -0.1404174 -0.010338774
Std. Error 0.9042738  0.4577001  1.858138516
t value    1.7991275 -0.3067890 -0.005564049
Pr(>|t|)   0.3229600  0.8104951  0.996457853
  > sapply(unique(data[[st]]), function(s)
+   summary(lm(FO, data, data[[st]] == s, data[[ws]]))$coef[1, ])  # !!!
Error in eval(substitute(subset), data, env) : object 's' not found
  > sapply(unique(data[[st]]), function(s)
+   summary(lm(y ~ x, data, data[[st]] == s, data[[ws]]))$coef[1, ])
                  [,1]       [,2]         [,3]
Estimate   1.6269038 -0.1404174 -0.010338774
Std. Error 0.9042738  0.4577001  1.858138516
t value    1.7991275 -0.3067890 -0.005564049
Pr(>|t|)   0.3229600  0.8104951  0.996457853
  > m <- matrix(NA, 4, length(unique(data[[st]])))
  > for (s in unique(data[[st]])) {
+   m[, s] <- summary(lm(FO, data, data[[st]] == s, data[[ws]]))$coef[1, ]
+ }
  > m
            [,1]       [,2]         [,3]
[1,] 1.6269038 -0.1404174 -0.010338774
[2,] 0.9042738  0.4577001  1.858138516
[3,] 1.7991275 -0.3067890 -0.005564049
[4,] 0.3229600  0.8104951  0.996457853

# DATA #################################################################

df1 <- structure(list(x = c(1.37095844714667, -0.564698171396089,
0.363128411337339,
0.63286260496104, 0.404268323140999, -0.106124516091484, 1.51152199743894,
-0.0946590384130976, 2.01842371387704), y = c(1.30824434809425,
0.740171482827397, 2.64977380403845, -0.755998096151299, 0.125479556323628,
-0.239445852485142, 2.14747239550901, -0.37891195982917, -0.638031707027734
), z = c(1L, 1L, 1L, 2L, 2L, 2L, 3L, 3L, 3L), w = c(0.7, 0.8,
1.2, 0.9, 1.3, 1.2, 0.8, 1, 1)), class = "data.frame", row.names = c(NA,
-9L))

FO <- y ~ x; data <- df1; st <- "z"; ws <- "w"; st1 <- 1

########################################################################

  > R.version
                 _
platform       x86_64-w64-mingw32
arch           x86_64
os             mingw32
system         x86_64, mingw32
status
major          3
minor          6.0
year           2019
month          04
day            26
svn rev        76424
language       R
version.string R version 3.6.0 (2019-04-26)
nickname       Planting of a Tree

#########################################################################

NOTE: Question on SO two days ago
(https://stackoverflow.com/questions/55893189/passing-formula-as-parameter-to-lm-within-sapply-causes-error-bug-confirmation)
brought many views but neither answer nor bug confirmation.

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