如何将数据子集存储在列表中? [英] How to subset data.frames stored in a list?
问题描述
这是一些代码来澄清我在说什么。假设 d1
和 d2
是我的数据框架
set.seed(1)
d1< -data.frame(a = rnorm(5),b = c(rep(2006,times = 4) )
d2< -data.frame(a = 1:5,b = c(2007,2007,NA,NA,2007))
print(d1)
ab
1.3011543 2006
0.3780023 2006
-0.3101449 2006
-1.3927445 2006
-1.0726218 NA
打印(d2)
ab
1 2007
2 2007
3 NA
4 NA
5 2007
我放在列表中
ls< -list()
r(i in 1:2){
str< -paste(d,i,sep =)
dat< -get(str)
ls [[str]]< -dat
}
喜欢过滤每个列表组件,以便只留下包含NA的列b的行。为此,我尝试使用以下命令,从一开始就知道它将失败。我的问题是我不知道如果 subset()
是正确的使用功能,如果是,我不知道如何限定每个数据帧(即子集功能的第一个元素)
lsNA< -lapply(ls,subset(ls,is.na (b)))
你能帮我超过我的严格限制吗?
lapply
的第二个参数是一个函数( / code>)和
子集
的额外参数作为 ...
参数传递到 lapply
。因此:
my.ls< - list(d1 = d1,d2 = d2)
my.lsNA< ; - lapply(my.ls,subset,is.na(b))
(我也是向您展示如何轻松创建data.frames列表,而不使用 get
,建议您不要使用 ls
作为一个变量名称,因为它也是一个相当常见的函数的名称。)
I created a list and I stored one data frame in each component. Now I would like to filter those data frames keeping only the rows that have NA in a specific column. I would like the result of this operation to be another list containing data frames with only those rows having NA in that column.
Here is some code to clarify what I am saying. Assume d1
and d2
are my data frames
set.seed(1)
d1<-data.frame(a=rnorm(5), b=c(rep(2006, times=4),NA))
d2<-data.frame(a=1:5, b=c(2007, 2007, NA, NA, 2007))
print(d1)
a b
1.3011543 2006
0.3780023 2006
-0.3101449 2006
-1.3927445 2006
-1.0726218 NA
print(d2)
a b
1 2007
2 2007
3 NA
4 NA
5 2007
which I place in a list
ls<-list()
r (i in 1:2){
str<-paste("d", i, sep="")
dat<-get(str)
ls[[str]]<-dat
}
Now I would like to filter each list component so to leave only rows of column b that contain NA. To do this I tried using the following command, knowing from the beginning it would have failed. My problem is that I don't know if subset()
is the right function to use and, in case it is, I don't know how to qualify each data frame (that is, the first element of the subset function)
lsNA<-lapply(ls, subset(ls, is.na(b)))
Can you please help me get past my severe limitations?
lapply
's second argument is a function (subset
) and extra arguments to subset
are passed as the ...
arguments to lapply
. Hence:
my.ls <- list(d1 = d1, d2 = d2)
my.lsNA <- lapply(my.ls, subset, is.na(b))
(I am also showing you how to easily create the list of data.frames without using get
, and recommend you don't use ls
as a variable name since it is also the name of a rather common function.)
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