[英]Using lapply to apply a function over list of data frames and saving output to files with different names
I have a list of data frames and have given each element in the list (eg each data frame) a name:我有一个数据框列表,并为列表中的每个元素(例如每个数据框)指定了一个名称:
eg例如
df1 <- data.frame(x = c(1:5), y = c(11:15))
df2 <- data.frame(x = c(1:5), y = c(11:15))
mylist <- list(A = df1, B = df2)
I have a function that I want to apply to each data frame;我有一个要应用于每个数据框的函数; In this function, I want to include a line to write the results to file (eventually I want to do more complicated things like save plots of the correlation between two variables for each data frame but thought I'd start simple)
在这个函数中,我想包括一行来将结果写入文件(最终我想做更复杂的事情,比如保存每个数据框的两个变量之间的相关性图,但我想我会从简单开始)
eg例如
NewVar <- function(mydata, whichVar, i) {
mydata$newVar <- mydata[, whichVar] + 1
write.csv(mydata, file = i)
}
I want to use lapply()
to apply this function to each data frame in my list我想使用
lapply()
将此函数应用于列表中的每个数据框
something like:就像是:
hh<-lapply(mylist, NewVar, whichVar = "y")
I can't figure out how to assign the "i" within the context of lapply so that i
iterates over the names in the list of data frames, saving multiple files with different names (in this case, two files named A
and B
) that correspond with the modified data frames.我不知道如何在 lapply 的上下文中分配“i”,以便
i
遍历数据框列表中的名称,保存具有不同名称的多个文件(在这种情况下,两个文件名为A
和B
)与修改后的数据帧相对应。
它将与以下lapply
调用一起使用:
lapply(names(mylist), function(x) NewVar(mylist[[x]], "y", x))
There are many options.有很多选择。 For example:
例如:
lapply(names(mylist),
function(x)write.csv(mylist[x],
file =paste0(x,'.csv')))
or using indexes :或使用索引:
lapply(seq_along(mylist),
function(i)write.csv(mylist[i],
file =paste0(names(mylist)[i],'.csv')))
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