'dimnames'[1]的長度不等於數組範圍'是什麼意思？

Question

我有data.frame，我可以積用matplot：

> dim(lhbyzone) 
[1] 38070 21 
> matplot(lhbyzone) 
(no error occurs here) 

但如果我把LH的頭部，並嘗試，它給了我一個奇怪的錯誤：

> foo <- head(lhbyzone,1000) 
> matplot(foo) 
Error in `rownames<-`(`*tmp*`, value = c("1", "2", "3", "4", "5", "6", : 
    length of 'dimnames' [1] not equal to array extent 

所以，可能與名字有關？

> dimnames(foo) 
[[1]] 
    [1] "1" "2" "3" "4" "5" "6" "7" "8" "9" "10" 
    [11] "11" "12" "13" "14" "15" "16" "17" "18" "19" "20" 
    [21] "21" "22" "23" "24" "25" "26" "27" "28" "29" "30" 
    [31] "31" "32" "33" "34" "35" "36" "37" "38" "39" "40" 
... 
[951] "951" "952" "953" "954" "955" "956" "957" "958" "959" "960" 
[961] "961" "962" "963" "964" "965" "966" "967" "968" "969" "970" 
[971] "971" "972" "973" "974" "975" "976" "977" "978" "979" "980" 
[981] "981" "982" "983" "984" "985" "986" "987" "988" "989" "990" 
[991] "991" "992" "993" "994" "995" "996" "997" "998" "999" "1000" 

[[2]] 
[1] "time" "z1" "z2" "z3" "z4" "z5" "z6" "z7" "z8" "z9" 
[11] "z10" "z11" "z12" "z13" "z14" "z15" "z16" "z17" "z18" "z19" 
[21] "z20" 

> dim(foo) 
[1] 1000 21 

> names(foo) 
[1] "time" "1" "2" "3" "4" "5" "6" "7" "8" "9" 
[11] "10" "11" "12" "13" "14" "15" "16" "17" "18" "19" 
[21] "20" 

尺寸看起來一樣嗎？這很奇怪，因爲原始框架上的matplot工作，但不在框架的頭部。這裏會發生什麼？

編輯，OK，所以回答一些問題，讓我們用thbyzone代替lhbyzone，因爲它的體積更小，讓我們用頭代替頭（..，1000），以使數據更小

> head(thbyzone) 
    time 1 2 3 4 5 6 7 8 9 10 11 
1 1 46 38 44 45 42 44 45 43 41 42 36 
2 2 46 36 42 43 42 43 44 44 39 43 32 
3 3 45 35 40 41 40 42 41 42 36 43 31 
4 4 41 30 36 37 39 38 40 34 35 39 30 
5 5 39 30 34 33 40 38 35 30 33 35 34 
6 6 35 29 32 32 41 37 35 35 36 35 35 

> dimnames(head(thbyzone)) 
[[1]] 
[1] "1" "2" "3" "4" "5" "6" 

[[2]] 
[1] "time" "1" "2" "3" "4" "5" "6" "7" "8" "9" 
[11] "10" "11" 

> matplot(head(thbyzone)) 
Error in `rownames<-`(`*tmp*`, value = c("1", "2", "3", "4", "5", "6", : 
    length of 'dimnames' [1] not equal to array extent 

> matplot(as.matrix(head(thbyzone))) 
Error in `rownames<-`(`*tmp*`, value = c("1", "2", "3", "4", "5", "6", : 
    length of 'dimnames' [1] not equal to array extent 

> matplot(thbyzone[1:6,]) 
Error in `rownames<-`(`*tmp*`, value = c("1", "2", "3", "4", "5", "6", : 
    length of 'dimnames' [1] not equal to array extent 

> class(thbyzone) 
[1] "cast_df" "data.frame" 

> str(thbyzone) 
List of 12 
$ time: num [1:39432] 1 2 3 4 5 6 7 8 9 10 ... 
$ 1 : int [1:39432] 46 46 45 41 39 35 33 33 36 47 ... 
$ 2 : int [1:39432] 38 36 35 30 30 29 28 28 28 33 ... 
$ 3 : int [1:39432] 44 42 40 36 34 32 30 30 30 32 ... 
$ 4 : int [1:39432] 45 43 41 37 33 32 30 29 30 41 ... 
$ 5 : int [1:39432] 42 42 40 39 40 41 38 33 36 43 ... 
$ 6 : int [1:39432] 44 43 42 38 38 37 36 36 38 44 ... 
$ 7 : int [1:39432] 45 44 41 40 35 35 33 30 31 39 ... 
$ 8 : int [1:39432] 43 44 42 34 30 35 34 33 34 41 ... 
$ 9 : int [1:39432] 41 39 36 35 33 36 32 31 31 35 ... 
$ 10 : int [1:39432] 42 43 43 39 35 35 33 33 35 42 ... 
$ 11 : int [1:39432] 36 32 31 30 34 35 32 30 28 30 ... 
- attr(*, "row.names")= int [1:39432] 1 2 3 4 5 6 7 8 9 10 ... 
- attr(*, "idvars")= chr "time" 
- attr(*, "rdimnames")=List of 2 
    ..$ :'data.frame': 39432 obs. of 1 variable: 
    .. ..$ time: num [1:39432] 1 2 3 4 5 6 7 8 9 10 ... 
    ..$ :'data.frame': 11 obs. of 1 variable: 
    .. ..$ station_id: int [1:11] 1 2 3 4 5 6 7 8 9 10 ... 

> traceback() 
.... lots of lines ... 
    "39405", "39406", "39407", "39408", "39409", "39410", "39411", 
    "39412", "39413", "39414", "39415", "39416", "39417", "39418", 
    "39419", "39420", "39421", "39422", "39423", "39424", "39425", 
    "39426", "39427", "39428", "39429", "39430", "39431", "39432" 
    )) 
4: as.matrix.cast_df(y) 
3: as.matrix(y) 
2: ncol(y <- as.matrix(y)) 
1: matplot(thbyzone[1:6, ]) 

一些更多的嘗試：

> foo <- head(thbyzone) 
> foo$time <- NULL 
> matplot(foo) 
Error in `rownames<-`(`*tmp*`, value = c("1", "2", "3", "4", "5", "6", : 
    length of 'dimnames' [1] not equal to array extent 
> head(foo) 
    1 2 3 4 5 6 7 8 9 10 11 
1 46 38 44 45 42 44 45 43 41 42 36 
2 46 36 42 43 42 43 44 44 39 43 32 
3 45 35 40 41 40 42 41 42 36 43 31 
4 41 30 36 37 39 38 40 34 35 39 30 
5 39 30 34 33 40 38 35 30 33 35 34 
6 35 29 32 32 41 37 35 35 36 35 35 

編輯：

> options(error=recover) 
> matplot(thbyzone[1:6,]) 
Error in `rownames<-`(`*tmp*`, value = c("1", "2", "3", "4", "5", "6", : 
    length of 'dimnames' [1] not equal to array extent 

Enter a frame number, or 0 to exit 

1: matplot(thbyzone[1:6, ]) 
2: ncol(y <- as.matrix(y)) 
3: as.matrix(y) 
4: as.matrix.cast_df(y) 
5: `rownames<-`(`*tmp*`, value = c("1", "2", "3", "4", "5", "6", "7", "8", "9" 

Answer 1

OK，我可以從s重現此與reshape（但不包含reshape2）。有些東西確實被head()弄壞了。

d <- data.frame(time=rep(1:10,10),x=rep(1:10,each=10),y=1:100) 
library(reshape2) 
str(dcast(d,time~x)) ## regular data frame 
detach("package:reshape2") 
library(reshape) 
str(z <- cast(d,time~x)) 
matplot(head(z)) ## error 

的具體問題是utils::head.data.frame之間和as.matrix.cast_df的相互作用，它降低所述對象的片段，而不會保持完全一致的內部結構，（由matplot稱爲），其中假定結構是存在的。

添加下面的方法似乎解決了這個問題。

head.cast_df <- function (x, n = 6L, ...) { 
    stopifnot(length(n) == 1L) 
    n <- if (n < 0L) { 
     max(nrow(x) + n, 0L) 
    } else min(n, nrow(x)) 
    h <- x[seq_len(n), , drop = FALSE] 
    ## fix cast_df-specific row names element 
    attr(h,"rdimnames")[[1]] <- rdimnames(h)[[1]][seq_len(n),,drop=FALSE] 
    h 
} 

這可能是值得這個維護者接觸，雖然reshape包棄用，取而代之的reshape2（我認爲）...

另一種解決方法是，如果可以從reshape::cast切換到reshape2::dcast ...