Count consecutive non NA items - r

Question

I have a dataset that looks like this:
library(purrr)
library(dplyr)
temp<-as.data.frame(cbind(col_A<-c(1,2,NA,3,4,5,6),col_B<-c(NA,1,2,NA,1,NA,NA)))
names(temp)<-c("col_A","col_B")
col_A col_B
1 NA
2 1
NA 2
3 NA
4 3
5 NA
6 NA
I want to create a new dataframe which contains the count of non NA items for each column.
Like the following example:
count_A count_B
1 0
2 1
0 2
1 0
2 1
3 0
4 0
I am strugling in getting the count of items.
My closest approximation is this:
count_days<-function(prev,new){
ifelse(!is.na(new),prev+1,0)
}
temp[,"col_A"] %>%
mutate(count_a=accumulate(count_a,count_days))
But I get the following error:
Error in UseMethod("mutate_") :
no applicable method for 'mutate_' applied to an object of class "c('double', 'numeric')"
Can anyone help me with this code or just give me another glance.
I know this piece of code just tries to count, not creating the new df, which I think is easier after I get the correct result.

Answer 1

Using rle in a (somewhat nested) lapply approach. We first list if an element of the data is.na. Then, using rle we decode values and lengths. Those lengths which are NA we set to 0 by multiplication and unlist the thing.
res <- as.data.frame(lapply(lapply(temp, is.na), function(x) {
r <- rle(x)
s <- sapply(r$lengths, seq_len)
s[r$values] <- lapply(s[r$values], `*`, 0)
unlist(s)
}))
res
# col_A col_B
# 1 1 0
# 2 2 1
# 3 0 2
# 4 1 0
# 5 2 1
# 6 3 0
# 7 4 0

Answer 2

We can use rleid from data.table
library(data.table)
setDT(temp)[, lapply(.SD, function(x) rowid(rleid(!is.na(x))) * !is.na(x))]
# col_A col_B
#1: 1 0
#2: 2 1
#3: 0 2
#4: 1 0
#5: 2 1
#6: 3 0
#7: 4 0

Answer 3

library(tidyverse)
You can use sequence and rle from data.table
First set all non-NA as 1 and then rle count the sequence of same numbers
library(data.table)
temp %>%
replace(.,!is.na(.),1) %>%
mutate(col_A=case_when(!is.na(col_A)~sequence(rle(col_A)$lengths))) %>%
mutate(col_B=case_when(!is.na(col_B)~sequence(rle(col_B)$lengths))) %>%
replace(.,is.na(.),0)