slicing of data into separate Dataframe

Question

I have a dataframe:

entry_df <- data.frame(date = seq(as.Date("2018/01/01"), as.Date("2018/01/07"), 
                       "days"),diff = c(1,0,-1 , 0,0 ,1,-1))

entry_df

        date diff
1 2018-01-01    1
2 2018-01-02    0
3 2018-01-03   -1
4 2018-01-04    0
5 2018-01-05    0
6 2018-01-06    1
7 2018-01-07   -1

I want to rbind the rows that are betwen 1 and -1 in a dataframe and push it on a list.

Steps:

1. 2018-01-01 is equal 1 so it will be my first element of my dataframe 2018-01-02 is equal to 0 so I need to rbind it to the first dataframe 2018-01-03 is equal to -1 so I need to rbind it to the first dataframe and that will constitue the first element of the list

2. 2018-01-04 and 2018-01-05 is equal to 0 so i don't do anything ...

3. 2018-01-06 is equal to 1 so i create a dataframe at it will be the first element of it. 2018-01-07 is equal to -1 so i will rbind to the dataframe and that will constitute the second element of the list

Expected output is something like this

output_list[[1]] <- data.frame(date = seq(as.Date("2018/01/01"), 
                               as.Date("2018/01/03"), "days")) 
output_list[[2]] <- data.frame(date = seq(as.Date("2018/01/06"),
                               as.Date("2018/01/07"), "days")) 

output_list      

[[1]]
        date
1 2018-01-01
2 2018-01-02
3 2018-01-03

[[2]]
        date
1 2018-01-06
2 2018-01-07

Answer 1

Assuming that the number of 1's and -1s are the same, get the index of row with == and which, then loop over the indexes using Map and subset the 1st column of 'entry_df'

Map(function(i, j) entry_df[i:j, 1, drop = FALSE], 
           which(entry_df$diff == 1), which(entry_df$diff == -1))
#[[1]]
#        date
#1 2018-01-01
#2 2018-01-02
#3 2018-01-03

#[[2]]
#        date
#6 2018-01-06
#7 2018-01-07