CODEWITHSUNDEEP
r
neversaint
neversaint

Reputation: 63994

How to systematically replace <NA> row with preceding values in R data frame

I have a data that looks like this:

FOO,yyy,Unigene126925_All,Unigene137063_All,0.238087
,,Unigene126925_All,Unigene24551_All,0.374231
,,Unigene126925_All,Unigene31835_All,0.367897
BAR,xxx,Unigene126925_All,Unigene165366_All,0.247844
,,Unigene126925_All,Unigene111784_All,0.344493

Which after reading it with the following code:

 dt <- read.csv("http://dpaste.com/1612639/plain/",header=FALSE,fill=FALSE,na.strings = "")
 # The <NA> coercion here is intentional.

It produces this result:

> dt
    V1   V2                V3                V4       V5
1  FOO  yyy Unigene126925_All Unigene137063_All 0.238087
2 <NA> <NA> Unigene126925_All  Unigene24551_All 0.374231
3 <NA> <NA> Unigene126925_All  Unigene31835_All 0.367897
4  BAR  xxx Unigene126925_All Unigene165366_All 0.247844
5 <NA> <NA> Unigene126925_All Unigene111784_All 0.344493

What I want to do is to replace the <NA> cells with the preceding values, yielding this:

FOO yyy Unigene126925_All Unigene137063_All 0.238087
FOO yyy Unigene126925_All  Unigene24551_All 0.374231
FOO yyy Unigene126925_All  Unigene31835_All 0.367897
BAR xxx Unigene126925_All Unigene165366_All 0.247844
BAR xxx Unigene126925_All Unigene111784_All 0.344493

In the above example the 2nd row has NA, it has to take the values for V1 and V2 columns from the preceding rows that contain the values.

How can I achieve that in R?

Upvotes: 1

Views: 177

Answers (1)

digEmAll
digEmAll

Reputation: 57210

You can use na.locf function (package zoo):

library(zoo)

dt$V1 <- na.locf(dt$V1) 
dt$V2 <- na.locf(dt$V2)

or in one shot:

dt <- na.locf(dt)

obtaining

> dt
   V1  V2                V3                V4       V5
1 FOO yyy Unigene126925_All Unigene137063_All 0.238087
2 FOO yyy Unigene126925_All  Unigene24551_All 0.374231
3 FOO yyy Unigene126925_All  Unigene31835_All 0.367897
4 BAR xxx Unigene126925_All Unigene165366_All 0.247844
5 BAR xxx Unigene126925_All Unigene111784_All 0.344493

Upvotes: 4

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