A query about na.omit

Lines <- "x     y     z

DF <- read.table(textConnection(Lines), header = TRUE)

# Now uses complete.cases to get required rows:

DF[complete.cases(DF[1:2]),]

Dear all,

Say I have the following dataset:

DF

? ? ? ?x ? ? y ? ? z
[1] ? 1 ? ? 1 ? ? 1
[2] ? 2 ? ? 2 ? ? 2
[3] ? 3 ? ? 3 ? ?NA
[4] ? 4 ? NA ? 4
[5] ?NA ?5 ? ? 5

And I want to omit all the rows which have NA, but only in columns X and Y, so that I get:

?x ?y ?z
1 ?1 ?1
2 ?2 ?2
3 ?3 ?NA

If I use na.omit(DF), I would delete the row for which z=NA, obtaining thus

x y z
1 1 1
2 2 2

But this is not what I want, of course.
If I use na.omit(DF[,1:2]), then I obtain

x y
1 1
2 2
3 3

which is OK for x and y columns, but I wouldn't get the corresponding values for z (ie 1 2 NA)

Any suggestions about how to obtain the desired results efficiently (the actual dataset has millions of records and almost 50 columns, and I would apply the procedure on 12 of these columns)?

Sincerely,

Jose Luis

Jose Luis Iparraguirre
Senior Research Economist
Economic Research Institute of Northern Ireland



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