list rbind 列表中的数据帧
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rbind dataframes in a list of lists
提问by bshor
I have a list of lists that looks like this: x[[state]][[year]]. Each element of this is a data frame, and accessing them individually is not a problem.
我有一个列表的列表，看起来像这样：x[[state]][[year]]。其中的每个元素都是一个数据框，单独访问它们不是问题。
However, I'd like to rbind data frames across multiple lists. More specifically, I'd like to have as output as many dataframes as I have years, that is rbind all the state data frames within each year. In other words, I'd like to combine all my state data, year by year, into separate data frames.
但是，我想在多个列表中绑定数据框。更具体地说，我希望输出尽可能多的数据帧，即 rbind 每年内的所有状态数据帧。换句话说，我想将我所有的州数据逐年合并到单独的数据框中。
I know that I can combine a single list into a data frame with do.call("rbind",list). But I don't know how I can do so across lists of lists.
我知道我可以将单个列表与do.call("rbind",list). 但我不知道如何跨列表执行此操作。
采纳答案by datanalytics.com
You can do something along the following lines (I could not test as I have no such structure):
您可以按照以下方式做一些事情（我无法测试，因为我没有这样的结构）：
extract.year <- function(my.year) lapply(x, function(y) y[[my.year]])
x.by.year <- sapply(my.list.of.years, function(my.year)
do.call(rbind, extract.year(my.year)))
The function extract year creates a list containing just the dataframes for the given year. Then you rbind them...
函数提取年份创建一个列表，其中仅包含给定年份的数据框。然后你绑定他们...
回答by hadley
Collapse it into a list first:
先把它折叠成一个列表：
list <- unlist(listoflists, recursive = FALSE)
df <- do.call("rbind", list)
