CODEWITHSUNDEEP
r
ToToRo
ToToRo

Reputation: 373

R: deal with list, calculate difference between each element value

I have a list called good, I want to calculate the difference between two values within each vector.

good[1:2]
[[1]] 
 [1]    8   16   28   38   53
[[2]]
 [1]    1    7    9   16   40

so I will get another list

good_dif1[1:2] 
[[1]]
 [1] 8 12 10 15 
[[2]]
 [2] 6 2 7 24

if I want insert a NA to first value, how can I do that?

so I will get another list

good_dif2[1:2]
[[1]] 
 [1] NA 8 12 10 15 
[[2]] 
 [2] NA 6 2 7 24

Upvotes: 3

Views: 3378

Answers (2)

Rich Scriven
Rich Scriven

Reputation: 99331

> good <- list(c(8, 16, 28, 38, 53), c(1, 7, 9, 16, 40)) 
> good_dif1 <- lapply(good, diff)  
> good_dif2 <- lapply(good_dif1, function(x) append(NA, x))
> good_dif2
## [[1]]
## [1] NA  8 12 10 15

## [[2]]
## [1] NA  6  2  7 24

Upvotes: 2

dvdkamp
dvdkamp

Reputation: 156

Use lapply

good <- list(c(NA,1,10,30,40), c(NA,3,4,5,10,20))
lapply(good, diff)

For the second part,

lapply(good, function(x)c(NA, diff(x)))

or

Map(c, NA, lapply(good, diff))

Hope that Helps.

Upvotes: 8

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