r - Variable definition with mutate that depends on its value in the previous row -

i have data in following format:

   time click       interaction 1   407 false              true 2   408  true              true 3   409 false             false 4   410 false             false 5   411 false             false 6   412 false             false 7   413 false             false 8   414 false             false 9   415 false             false 10  416 false             false 11  417 false             false 12  418 false             false 13  419 false             false 14  420 false             false 15  421 false             false 16  422 false             false 17  423 false             false 18  424 false             false 19  425 false             false 20  426 false             false 21  427 false             false 22  428 false             false 23  429 false             false 24  430 false             false 25  431 false             false 26  432 false             false 27  433 false             false 28  434 false             false 29  435 false              true 30  436 false             false 

it represents how user interacts application every second (clicks, , other interaction events typing, scrolling, etc., , interaction true when there's interaction, click or otherwise). i'd compute new variable true in span there's no interaction after clicking until start interacting again.

so new variable, want true if there was:

• a click in last second , no interaction (click or otherwise) in current second, or
• no interaction after click in last second, , there's still no interaction in current second.

i tried dplyr:

activity %>% mutate(     nothing.after.click = (lag(click) == true & interaction == false) |         (lag(nothing.after.click) == true & interaction == false) ) 

but unfortunately doesn't work (it says "error: object 'nothing.after.click' not found"). how can this? if isn't possible dplyr, welcome use of else.

this output i'd like:

   time click       interaction nothing.after.click 1   407 false              true               false 2   408  true              true               false 3   409 false             false                true 4   410 false             false                true 5   411 false             false                true 6   412 false             false                true 7   413 false             false                true 8   414 false             false                true 9   415 false             false                true 10  416 false             false                true 11  417 false             false                true 12  418 false             false                true 13  419 false             false                true 14  420 false             false                true 15  421 false             false                true 16  422 false             false                true 17  423 false             false                true 18  424 false             false                true 19  425 false             false                true 20  426 false             false                true 21  427 false             false                true 22  428 false             false                true 23  429 false             false                true 24  430 false             false                true 25  431 false             false                true 26  432 false             false                true 27  433 false             false                true 28  434 false             false                true 29  435 false              true               false 30  436 false             false               false 

ultimately, goal filter these rows nothing.after.click true, if there's way think problem i'd welcome too.

you can't reference variable in initial definition. can do in multiple passes.

when @ conditions:

nothing.after.click = (lag(click) == true & interaction == false) |         (lag(nothing.after.click) == true & interaction == false) 

i see interaction == false in both possibilities. so, if interaction true, nothing.after.click (from here on out nac) false. otherwise, i'm not sure yet i'll set na. that's first pass:

dat %>% mutate(nac = ifelse(interaction, false, na)) 

we've taken care of interaction == false part, next pass lag(click) == true part of or clause. na, therefore undecided yet, true if lag(click) true, otherwise we'll leave untouched. (== true redundant, left out.)

dat %>% mutate(nac = ifelse(interaction, false, na),                nac = ifelse(lag(click) & is.na(nac), true, nac)) 

for last pass lag(nac) part, still undefined set previous defined value. job zoo:na.locf (locf stands "last observation carried forward"):

library(zoo) dat %>% mutate(nac = ifelse(interaction, false, na),                nac = ifelse(lag(click) & is.na(nac), true, nac),                nac = na.locf(nac))  #    time click interaction   nac # 1   407 false        true false # 2   408  true        true false # 3   409 false       false  true # 4   410 false       false  true # 5   411 false       false  true # 6   412 false       false  true # 7   413 false       false  true # 8   414 false       false  true # 9   415 false       false  true # 10  416 false       false  true # 11  417 false       false  true # 12  418 false       false  true # 13  419 false       false  true # 14  420 false       false  true # 15  421 false       false  true # 16  422 false       false  true # 17  423 false       false  true # 18  424 false       false  true # 19  425 false       false  true # 20  426 false       false  true # 21  427 false       false  true # 22  428 false       false  true # 23  429 false       false  true # 24  430 false       false  true # 25  431 false       false  true # 26  432 false       false  true # 27  433 false       false  true # 28  434 false       false  true # 29  435 false        true false # 30  436 false       false false