How Do I Change Column Content Based On Previous Row?

Apologies. Whenever I try to make them into tables rather than into code it seems to think I have a code embedded and won't let me post this. So here's an example of What I have H

Solution 1:

Edit Thanks to r2evans now without rowwise().

Perhaps this is what you are looking for:

library(dplyr)
library(tidyr)

df %>% 
  mutate(Begin_New = Map(seq, Begin, End - 6000, list(by = 1000))) %>% 
  unnest(Begin_New) %>% 
  group_by(ID, File, Period) %>% 
  mutate(End_New = ifelse(Begin_New + 7000 > End, End, Begin_New + 6000))

returns

# A tibble: 428 x 10
   ID    File         Period   Begin   End Laser1 Laser2 Lead   Begin_New End_New
   <chr> <chr>        <chr>    <dbl> <dbl> <chr>  <chr>  <chr>      <dbl>   <dbl>
 1 A01   longname.zip Baseline     0 30500 qfin   plethh plethi         0    6000
 2 A01   longname.zip Baseline     0 30500 qfin   plethh plethi      1000    7000
 3 A01   longname.zip Baseline     0 30500 qfin   plethh plethi      2000    8000
 4 A01   longname.zip Baseline     0 30500 qfin   plethh plethi      3000    9000
 5 A01   longname.zip Baseline     0 30500 qfin   plethh plethi      4000   10000
 6 A01   longname.zip Baseline     0 30500 qfin   plethh plethi      5000   11000
 7 A01   longname.zip Baseline     0 30500 qfin   plethh plethi      6000   12000
 8 A01   longname.zip Baseline     0 30500 qfin   plethh plethi      7000   13000
 9 A01   longname.zip Baseline     0 30500 qfin   plethh plethi      8000   14000
10 A01   longname.zip Baseline     0 30500 qfin   plethh plethi      9000   15000
11 A01   longname.zip Baseline     0 30500 qfin   plethh plethi     10000   16000
12 A01   longname.zip Baseline     0 30500 qfin   plethh plethi     11000   17000
13 A01   longname.zip Baseline     0 30500 qfin   plethh plethi     12000   18000
14 A01   longname.zip Baseline     0 30500 qfin   plethh plethi     13000   19000
15 A01   longname.zip Baseline     0 30500 qfin   plethh plethi     14000   20000
16 A01   longname.zip Baseline     0 30500 qfin   plethh plethi     15000   21000
17 A01   longname.zip Baseline     0 30500 qfin   plethh plethi     16000   22000
18 A01   longname.zip Baseline     0 30500 qfin   plethh plethi     17000   23000
19 A01   longname.zip Baseline     0 30500 qfin   plethh plethi     18000   24000
20 A01   longname.zip Baseline     0 30500 qfin   plethh plethi     19000   25000
21 A01   longname.zip Baseline     0 30500 qfin   plethh plethi     20000   26000
22 A01   longname.zip Baseline     0 30500 qfin   plethh plethi     21000   27000
23 A01   longname.zip Baseline     0 30500 qfin   plethh plethi     22000   28000
24 A01   longname.zip Baseline     0 30500 qfin   plethh plethi     23000   29000
25 A01   longname.zip Baseline     0 30500 qfin   plethh plethi     24000   30500
26 A01   longname.zip Run      30500 68500 qfin   plethh plethi     30500   36500
27 A01   longname.zip Run      30500 68500 qfin   plethh plethi     31500   37500
28 A01   longname.zip Run      30500 68500 qfin   plethh plethi     32500   38500
29 A01   longname.zip Run      30500 68500 qfin   plethh plethi     33500   39500
30 A01   longname.zip Run      30500 68500 qfin   plethh plethi     34500   40500

I named the columns Begin_New and End_New, you could change that easily into Begin and End.