CODEWITHSUNDEEP
rmatrixvector
Владимир Кузовкин
Владимир Кузовкин

Reputation: 622

r taking last and first non NA elements from vector

I have a data frame 

a = c(NA,NA,NA,NA,NA,40,32,46,98,900,NA,NA,78,87,43,78,NA,NA,NA)
b = c(1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19)
d = cbind(a,b)

I want to get part of this data from the first non NA element to the last one.Tha results should be:

40 32 46 98 900 NA Na 78 87 43 78
6   7  8  9  10 11 12 13 14 15 16

How should I solve my problem?

Upvotes: 2

Views: 68

Answers (2)

tmfmnk
tmfmnk

Reputation: 40171

One base R possibility could be:

d[rev(cumsum(rev(!is.na(a)))) != 0 & cumsum(!is.na(a)) != 0, ]

        a  b
 [1,]  40  6
 [2,]  32  7
 [3,]  46  8
 [4,]  98  9
 [5,] 900 10
 [6,]  NA 11
 [7,]  NA 12
 [8,]  78 13
 [9,]  87 14
[10,]  43 15
[11,]  78 16

In individual steps:

rev(cumsum(rev(!is.na(a))))

 [1] 9 9 9 9 9 9 8 7 6 5 4 4 4 3 2 1 0 0 0

cumsum(!is.na(a))

 [1] 0 0 0 0 0 1 2 3 4 5 5 5 6 7 8 9 9 9 9

rev(cumsum(rev(!is.na(a)))) != 0 & cumsum(!is.na(a)) != 0

 [1] FALSE FALSE FALSE FALSE FALSE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE
[14]  TRUE  TRUE  TRUE FALSE FALSE FALSE

Upvotes: 0

Rushabh Patel
Rushabh Patel

Reputation: 2764

You can use na.trim function from zoo package

> zoo::na.trim(d)

    a  b
6   40  6
7   32  7
8   46  8
9   98  9
10 900 10
11  NA 11
12  NA 12
13  78 13
14  87 14
15  43 15
16  78 16

Note- You can also look for sides argument of na.trim function for more alteration.

Upvotes: 1

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