Calculate cumsum() while ignoring NA values

It's an old question but tidyr gives a new solution. Based on the idea of replacing NA with zero.

require(tidyr)

cumsum(replace_na(x, 0))

 a  b  c  d  e  f  g  h 
 1  3  3  3  7  7  7 13

You can do this in one line with:

cumsum(ifelse(is.na(x), 0, x)) + x*0
#  a  b  c  d  e  f  g  h 
#  1  3  3 NA  7 NA NA 13

Or, similarly:

library(dplyr)
cumsum(coalesce(x, 0)) + x*0
#  a  b  c  d  e  f  g  h 
#  1  3  3 NA  7 NA NA 13

Do you want something like this:

x2 <- x
x2[!is.na(x)] <- cumsum(x2[!is.na(x)])

x2

[edit] Alternatively, as suggested by a comment above, you can change NA's to 0's -

miss <- is.na(x)
x[miss] <- 0
cs <- cumsum(x)
cs[miss] <- NA
# cs is the requested cumsum

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