R - 將可變大小的列表展平到數據框？

Question

我想將可變大小的列表平鋪到單個數據框中。除了每個列表可以具有不同數量的元素之外，這很容易。

下面是一個更好地描述問題的例子。有兩場音樂會。第一場音樂會有兩個樂隊。第二場音樂會只有一個樂隊。

> concert1 <- list(bands=list(band=list("Foo Fighters","Ace of Base"), venue="concert hall 1")) 
> concert2 <- list(bands=list(band=list("The Black Keys"), venue="concert hall 2")) 
> concertsList <- list(concert1=concert1, concert2=concert2) 

> str(concertsList) 
List of 2 
$ concert1:List of 1 
    ..$ bands:List of 2 
    .. ..$ band :List of 2 
    .. .. ..$ : chr "Foo Fighters" 
    .. .. ..$ : chr "Ace of Base" 
    .. ..$ venue: chr "concert hall 1" 
$ concert2:List of 1 
    ..$ bands:List of 2 
    .. ..$ band :List of 1 
    .. .. ..$ : chr "The Black Keys" 
    .. ..$ venue: chr "concert hall 2" 

我想將'concertsList'拼成一個看起來像下面這樣的數據框。

> data.frame(concert=c("concert1","concert2"), band.1=c("Foo Fighers", "The Black Keys"), band.2=c("Ace of Base", NA), venues=c("concert hall 1", "concert hall 2")) 

    concert   band.1  band.2   venues 
1 concert1 Foo Fighers Ace of Base concert hall 1 
2 concert2 The Black Keys  <NA> concert hall 2 

您的想法將不勝感激。

Answer 1

library(plyr) 
DF <- as.data.frame(
    do.call(rbind.fill.matrix, 
      lapply(concertsList, function(l) { 
      res <- unlist(l) 
      names(res)[names(res)=="bands.band"] <- "bands.band1" 
      t(res) 
      }) 
) 
) 

DF$concert <- names(concertsList) 
names(DF) <- gsub("bands.","",names(DF)) 

#   band1  band2   venue concert 
#1 Foo Fighters Ace of Base concert hall 1 concert1 
#2 The Black Keys  <NA> concert hall 2 concert2