CODEWITHSUNDEEP
rsubset
jtdoud
jtdoud

Reputation: 136

subsetting data frame without using column names

I'm wondering if there is a better way to do this or if I might be running into some unforeseen trouble. I need to subset from a data frame but I do not want to use the column names. I'd need do it by referencing the column number.

data <- data.frame(col1= c(50, 20, NA, 100, 50), 
                   col2= c(NA, 25, 125, 50, NA),
                   col3= c(NA, 100, 15, 55, 25),
                   col4= c(NA, 30, 125, 100, NA),
                   col5= c(80, 25, 75, 40, NA))

Suppose I want to subset the data frame and keep only the row that contain 3 consecutive NAs before a valid number in column 5. Best I can come up with without using column names is this:

sub <- data[(which(is.na(data[2]) & 
                   is.na(data[3]) & 
                   is.na(data[4]) & 
                   !is.na(data[5]))), ]

Anyone see any trouble with this or know of a better way? I'm worried about using subsets within subsets although every thing appears to be working as it should.

Upvotes: 4

Views: 814

Answers (1)

A5C1D2H2I1M1N2O1R2T1
A5C1D2H2I1M1N2O1R2T1

Reputation: 193677

If you're looking to condense your code a little, you can do something like:

> data[rowSums(is.na(data[2:4])) == 3 & !is.na(data[5]), ]
  col1 col2 col3 col4 col5
1   50   NA   NA   NA   80

Upvotes: 4

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