Clever Geek Handbook

Encoding the total length of the data frame in R

I have a data frame that contains values ​​related to observations, 1 or 0. I want to count continuous occurrences of 1 by resetting to 0. The run length encoding ( rle

) function seems to be as if it were doing but I cannot handle receiving data in desired format. I want to try doing this without writing a custom function. In the data below I have an observation on a dataframe, then I want to get a "persistent" column and write back to the dataframe. This link was a good start .

observation continual 
          0         0
          0         0
          0         0
          1         1
          1         2
          1         3
          1         4
          1         5
          1         6
          1         7
          1         8
          1         9
          1        10
          1        11
          1        12
          0         0
          0         0
+3


source to share


5 answers


You can do this quite easily in a couple of steps:



x <- rle(mydf$observation)       ## run rle on the relevant column
new <- sequence(x$lengths)       ## create a sequence of the lengths values
new[mydf$observation == 0] <- 0  ## replace relevant values with zero
new
#  [1]  0  0  0  1  2  3  4  5  6  7  8  9 10 11 12  0  0
+7


source


Using devel version you can try



library(data.table) ## v >= 1.9.5
setDT(df)[, continual := seq_len(.N) * observation, by = rleid(observation)]
+7


source


There is probably a better way, but:

g <- c(0,cumsum(abs(diff(df$obs))))
df$continual <- ave(g,g,FUN=seq_along)
df$continual[df$obs==0] <- 0
+4


source


Just adapt the accepted answer from your linked question:

unlist(mapply(function(x, y) seq(x)*y, rle(df$obs)$lengths, rle(df$obs)$values))
# [1]  0  0  0  1  2  3  4  5  6  7  8  9 10 11 12 0  0
+3


source


You can use a simple basic R

one liner using a fact observation containing only 0

and 1

, combined with a vectorized operation:

transform(df, continual=ifelse(observation, cumsum(observation), observation))

#   observation continual
#1            0         0
#2            0         0
#3            0         0
#4            1         1
#5            1         2
#6            1         3
#7            1         4
#8            1         5
#9            1         6
#10           1         7
#11           1         8
#12           1         9
#13           1        10
#14           1        11
#15           1        12
#16           0         0
#17           0         0
+2


source






More articles:


All Articles