Remove Columns from Dataframe Where Some of Values Are Na
I Have a Dataframe Where Some of the Values Are Na. I Would Like to Remove These Columns. My Data. Frame Looks Like This V1 V2 1 1 Na 2 1 1 3 2 2 4 1 1 5 2 2 6...
I have a dataframe where some of the values are NA. I would like to remove these columns.
My data.frame looks like this
v1 v2
1 1 NA
2 1 1
3 2 2
4 1 1
5 2 2
6 1 NA
I tried to estimate the col mean and select the column means !=NA. I tried this statement, it does not work.
data=subset(Itun, select=c(is.na(colMeans(Itun))))
I got an error,
error : 'x' must be an array of at least two dimensions
Can anyone give me some help?
7 Answers
The data:
Itun <- data.frame(v1 = c(1,1,2,1,2,1), v2 = c(NA, 1, 2, 1, 2, NA))
This will remove all columns containing at least one NA:
Itun[ , colSums(is.na(Itun)) == 0]
An alternative way is to use apply:
Itun[ , apply(Itun, 2, function(x) !any(is.na(x)))]
Here's a convenient way to do it using the dplyr function select_if(). Combine not (!), any() and is.na(), which is equivalent to selecting all columns that don't contain any NA values.
library(dplyr)
Itun %>%
select_if(~ !any(is.na(.)))
You can use transpose twice:
newdf <- t(na.omit(t(df)))
Alternatively, select(where(~FUNCTION)) can be used:
library(dplyr)
(df <- data.frame(x = letters[1:5], y = NA, z = c(1:4, NA)))
#> x y z
#> 1 a NA 1
#> 2 b NA 2
#> 3 c NA 3
#> 4 d NA 4
#> 5 e NA NA
# Remove columns where all values are NA
df %>%
select(where(~!all(is.na(.))))
#> x z
#> 1 a 1
#> 2 b 2
#> 3 c 3
#> 4 d 4
#> 5 e NA
# Remove columns with at least one NA
df %>%
select(where(~!any(is.na(.))))
#> x
#> 1 a
#> 2 b
#> 3 c
#> 4 d
#> 5 e
data[,!apply(is.na(data), 2, any)]
A base R method related to the apply answers is
Itun[!unlist(vapply(Itun, anyNA, logical(1)))]
v1
1 1
2 1
3 2
4 1
5 2
6 1
Here, vapply is used as we are operating on a list, and, apply, it does not coerce the object into a matrix. Also, since we know that the output will be logical vector of length 1, we can feed this to vapply and potentially get a little speed boost. For the same reason, I used anyNA instead of any(is.na()).
Another alternative with the dplyr package would be to make use of the Filter function
Filter(function(x) !any(is.na(x)), Itun)
with data.table would be a little more cumbersome
setDT(Itun)[,.SD,.SDcols=setdiff((1:ncol(Itun)),
which(colSums(is.na(Itun))>0))]