Adding lists names as plot titles in lapply call in R

Question

sample <- 
structure(list(GB05 = structure(c(22L, 34L, 26L, 2L), .Dim = 4L, .Dimnames = structure(list(
    c("98", "100", "102", "106")), .Names = ""), class = "table"), 
    GB18 = structure(c(8L, 14L, 70L), .Dim = 3L, .Dimnames = structure(list(
        c("173", "175", "177")), .Names = ""), class = "table"), 
    GB06 = structure(c(2L, 16L, 48L, 10L, 10L, 6L), .Dim = 6L, .Dimnames = structure(list(
        c("234", "238", "240", "242", "244", "246")), .Names = ""), class = "table"), 
    GB27 = structure(c(2L, 28L, 2L, 2L, 4L, 3L, 2L, 2L, 15L, 
    17L, 4L, 5L), .Dim = 12L, .Dimnames = structure(list(c("145", 
    "147", "149", "151", "156", "159", "165", "167", "169", "171", 
    "173", "175")), .Names = ""), class = "table"), GB24 = structure(c(2L, 
    4L, 41L, 10L, 6L, 2L, 14L, 2L, 3L), .Dim = 9L, .Dimnames = structure(list(
        c("240", "241", "242", "243", "244", "247", "249", "251", 
        "253")), .Names = ""), class = "table"), GB28 = structure(c(30L, 
    22L, 2L, 10L, 2L, 4L, 2L, 2L, 2L), .Dim = 9L, .Dimnames = structure(list(
        c("363", "364", "365", "367", "371", "377", "380", "384", 
        "390")), .Names = ""), class = "table"), GB15 = structure(c(12L, 
    16L, 43L, 2L, 3L, 4L), .Dim = 6L, .Dimnames = structure(list(
        c("142", "144", "146", "147", "148", "152")), .Names = ""), class = "table"), 
    GB02 = structure(c(6L, 78L, 4L), .Dim = 3L, .Dimnames = structure(list(
        c("194", "197", "200")), .Names = ""), class = "table"), 
    GB10 = structure(c(2L, 36L, 7L, 1L, 16L, 20L), .Dim = 6L, .Dimnames = structure(list(
        c("124", "126", "128", "130", "132", "134")), .Names = ""), class = "table"), 
    GB14 = structure(c(3L, 6L, 7L, 37L, 7L), .Dim = 5L, .Dimnames = structure(list(
        c("181", "184", "187", "193", "196")), .Names = ""), class = "table")), .Names = c("GB05", 
"GB18", "GB06", "GB27", "GB24", "GB28", "GB15", "GB02", "GB10", 
"GB14"))

How to get the names in this list to appear as plot titles in this lapply call (one title for each plot) ?

dev.new()
par(mfrow=c(2,5))
lapply(sample,function(x) plot(x,main=names[x]))

I don't understand why main=names[x] won't work.

Answer 1

Use lapply on the names of the list items instead:

lapply(names(afn), function(x) plot(afn[[x]], main=x))

To see why you aren't getting your names, run lapply(afn, function(x) names(x)) gives you the names of each list item or something else. Try the same with lapply(names(afn), function(x) x) and compare the difference. Then, remember that we can extract a single list item by name by using [[.