导入多个文件并为其编制索引 [英] Importing several files and indexing them
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问题描述
我有n个文件,file_1,file_2,...,file_n,我想导入和使用它们。所以我导入这样的文件
I have n files, file_1, file_2,..., file_n that I want to import and work with. So I import the files like this
files <- list.files(pattern=".txt$")
for(i in files) {
x <- read.table(i, header=TRUE, comment.char = "A", sep="\t")
assign(i, x)
}
重点是我想同时使用不同文件中的数据。例如,我想计算每个文件的第一列的均值向量:
The point is that I want to use data simultaneously from the different files. For example I want to compute the means vector of the first column of each file:
meanv = mean(file_1$firstcolumn, file_2$firstcolumn, ..., file_n$firstcolumn).
执行此操作的最合理方法是写入遍历所有文件的循环( file_1
, file_2
,..., file_n
)。在这种情况下,您需要索引文件。这有什么解决方案吗?还是有其他解决方案。
the most logical way to do this is the write a loop going through all files (file_1
, file_2
,..., file_n
). In this case you need to index the files. Is there any solution to this? Or is there any other solution.
推荐答案
只需使用清单:
##Generate some test data
R> dd1 = data.frame(V1 = rnorm(10), V2 = rnorm(10))
R> dd2 = data.frame(V1 = rnorm(10), V2 = rnorm(10))
#Create an empty list
R> l = list()
##In your example, you would have something like:
##l[[i]] = read.table(....)
R> l[[1]] = dd1; l[[2]] = dd2
##Now use lapply to calculate the column means for each data frame
R> lapply(l, colMeans)
[[1]]
V1 V2
-0.6805 -0.0767
[[2]]
V1 V2
0.253563 0.006207
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