在 R 中显示 plot 图例中的数字

Question

I was wondering why numerical values of pop_mean = 10; pop_mean_sd = 5; within_sd = 3 pop_mean = 10; pop_mean_sd = 5; within_sd = 3 pop_mean = 10; pop_mean_sd = 5; within_sd = 3 don't show in the legend of my plot below? Is there a fix?

pop_mean = 10 ; pop_mean_sd = 5 ; within_sd = 3

plot(1)
legend("top",      c(expression(mu[i]*"~"*N(.(pop_mean)*","*.(pop_mean_sd))), 
                     expression(Math[ij]*"~"*N(mu[i]*","*.(within_sd)))),
                      bty = "n", cex = .8, 
                    inset = c(0, -.17), xpd = NA)

Answer 1

Here's an approach using bquote .

From help(bquote) :

An analogue of the LISP backquote macro. bquote quotes its argument except that terms wrapped in.() are evaluated in the specified where environment.

Therefore, anything within .() is evaluated, which should be what you're looking for. Using c() with bquote makes a list of calls, which doesn't work with legend . So you can use as.expression to convert to a usable expression.

plot(1)
legend("top",
       as.expression(c(bquote(mu[i]*"~"*N(.(pop_mean)*","*.(pop_mean_sd))),
                       bquote(Math[ij]*"~"*N(mu[i]*","*.(within_sd))))),
       bty = "n", cex = .8, 
       inset = c(0, 0), xpd = NA)

A similar approach could be with substitute :

legend("top",
       legend = as.expression(c(substitute(mu[i]*"~"*N(pop_mean*","*pop_mean_sd),
                                                 list(pop_mean=pop_mean, pop_mean_sd = pop_mean_sd)),
                                      substitute(italic(Math)[ij]*"~"*N(mu[i]*","*within_sd),
                                                 list(within_sd=within_sd)))),
       bty = "n", cex = .8, 
       inset = c(0, 0), xpd = NA)