You can try either of these: expr <- bquote(lm(.(as.formula(mod)), dat)) lm_out5 <- eval(expr)
expr <- call("lm", as.formula(mod), as.symbol("dat")) lm_out6 <- eval(expr) but bquote is usually easier and good enough. On Wed, Oct 25, 2023, 05:10 Shu Fai Cheung <shufai.che...@gmail.com> wrote: > Hi All, > > I have a problem that may have a simple solution, but I am not > familiar with creating calls manually. > > This is example calling lm() > > ``` r > set.seed(1234) > n <- 10 > dat <- data.frame(x1 = rnorm(n), > x2 = rnorm(n), > y = rnorm(n)) > > lm_out <- lm(y ~ x1 + x2, dat) > lm_out > #> > #> Call: > #> lm(formula = y ~ x1 + x2, data = dat) > #> > #> Coefficients: > #> (Intercept) x1 x2 > #> -0.5755 -0.4151 -0.2411 > lm_out$call > #> lm(formula = y ~ x1 + x2, data = dat) > ``` > > The call is stored, "lm(formula = y ~ x1 + x2, data = dat)", and names > are not evaluated. > > I want to create a similar call, but only one of the elements is from a > string. > > ```r > mod <- "y ~ x1 + x2" > ``` > > This is what I tried but failed: > > ```r > lm_out2 <- do.call("lm", > list(formula = as.formula(mod), > data = dat)) > lm_out2 > #> > #> Call: > #> lm(formula = y ~ x1 + x2, data = structure(list(x1 = > c(-1.20706574938542, > #> 0.27742924211066, 1.08444117668306, -2.34569770262935, 0.42912468881105, > #> 0.506055892157574, -0.574739960134649, -0.546631855784187, > -0.564451999093283, > #> -0.890037829044104), x2 = c(-0.477192699753547, -0.998386444859704, > #> -0.77625389463799, 0.0644588172762693, 0.959494058970771, > -0.110285494390774, > #> -0.511009505806642, -0.911195416629811, -0.83717168026894, > 2.41583517848934 > #> ), y = c(0.134088220152031, -0.490685896690943, -0.440547872353227, > #> 0.459589441005854, -0.693720246937475, -1.44820491038647, > 0.574755720900728, > #> -1.02365572296388, -0.0151383003641817, -0.935948601168394)), class > = "data.frame", row.names = c(NA, > #> -10L))) > #> > #> Coefficients: > #> (Intercept) x1 x2 > #> -0.5755 -0.4151 -0.2411 > ``` > > It does not have the formula, "as a formula": y ~ x1 + x2. > However, the name "dat" is evaluated. Therefore, the call stored does > not have the name 'dat', but has the evaluated content. > > The following fits the same model. However, the call stores the name, > 'mod', not the evaluated result, y ~ x1 + x2. > > ```r > lm_out3 <- lm(mod, data = dat) > lm_out3 > #> > #> Call: > #> lm(formula = mod, data = dat) > #> > #> Coefficients: > #> (Intercept) x1 x2 > #> -0.5755 -0.4151 -0.2411 > ``` > > The following method works. However, I have to do a dummy call, > extract the stored call, and set formula to the result of > as.formula(mod): > > ```r > lm_out3 <- lm(mod, data = dat) > lm_out3 > #> > #> Call: > #> lm(formula = mod, data = dat) > #> > #> Coefficients: > #> (Intercept) x1 x2 > #> -0.5755 -0.4151 -0.2411 > > call1 <- lm_out3$call > call1$formula <- as.formula(mod) > lm_out4 <- eval(call1) > lm_out4 > #> > #> Call: > #> lm(formula = y ~ x1 + x2, data = dat) > #> > #> Coefficients: > #> (Intercept) x1 x2 > #> -0.5755 -0.4151 -0.2411 > ``` > > Is it possible to create the call directly, with only 'mod' evaluated, > and other arguments, e.g., 'dat', not evaluated? > > Regards, > Shu Fai > > ______________________________________________ > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide > http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. > [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.