look and say sequence

look_and_say_sequence.R

# https://mathworld.wolfram.com/LookandSaySequence.html

library(ggplot2)
library(stringi)

tic <- Sys.time()
len <- 68
s <- rep(NA, len)
s[1] <- 1
tm <- rep(NA, len)

for (i in seq_len(len)) {
    sp <- rle(strsplit(as.character(s[i]), '')[[1]])
    s[i+1] <- paste(sp[[1]], sp[[2]], sep = '', collapse = '')
    #cat(s[i+1], '\n')
    t <- table(unlist(stringi::stri_extract_all_regex(s, "[0-9]")))
    tm[i] <- as.numeric(difftime(Sys.time(), tic, units = 'secs'))
    cat(i, '. ', paste0(round(100*t/sum(t), 1), '%', collapse = ' '), '     ', round(tm[i], 1), 's\n', sep =''); flush.console()
}

#nchar(s)


#t <- table(unlist(stringi::stri_extract_all_regex(s, "[0-9]"))); paste0(round(100*t/sum(t), 1), '%\n')
data = data.frame(i=seq_len(len), t=tm)
ggplot2::ggplot(data, ggplot2::aes(x=i, y=t)) +
    #ggplot2::geom_line() +
    ggplot2::geom_point() +
    #ggplot2::geom_smooth(method =stats::loess) +
    ggformula::geom_spline()



data.frame(i=seq_len(len), t=tm)

#mod <- lm(t~i, data=data)
mod <-loess(t~i, data=data, control=loess.control(surface="direct"))
mod <- with(data, smooth.spline(i, t))
new <- data.frame(i = (len + 1):(len + 20), t=NA)
new$t <- predict(mod, new$i)$y
rbind(data, new)


chars <- nchar(s)
datac = data.frame(i=seq_len(len), c = chars)[-70,]

modc <-loess(c~i, data=datac, control=loess.control(surface="direct"))
modc <- with(datac, smooth.spline(i, c))
new <- data.frame(i = (len + 1):(len + 20), c=NA)
new$c <- predict(modc, new$i)$y
rbind(datac, new)

library(pryr)
object_size(s)