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

[Jens Heumann]

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?

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.