In dgkf/riddlr: A package for building interactive programming challenges

Question

You're given a numeric vector of ages in years for people ranging from just a few seconds old to nearly 100 years old. For printing, you would prefer to use the largest unit for which the age rounds down to a positive integer (e.g. "33 mins old" instead of "6.46e-5 years old"). Additionally, you want to indicate a plural unit when the next lowest positive integer is greater than 1.

For unit conversions, a numeric vector, conversions, has been provided to convert from years according to the following conversions:

conversions <- c(
  year  = 1,                #  1 year  =  1 year
  month = 365.25/30.5,      #  1 year  =  365.25 days
  week  = 365.25/7,         #  1 week  =  7 days
  day   = 365.25,           #  1 month =  30.5 days
  hour  = 365.25*24,        #  1 day   =  24 hours
  min   = 365.25*24*60,     #  1 hour  =  60 mins
  sec   = 365.25*24*60*60)  #  1 min   =  60 secs

For example, given the following ages in years

ages <- c(0.000001, 0.00001, 0.0001, 0.001, 0.01, 0.1, 1, 10)

Your resulting character vector would be

c("31 secs old", "5 mins old", "52 mins old", "8 hours old", "3 days old", 
    "1 month old", "1 year old", "10 years old")

conversions <- c(
  year = 1, 
  month = 365.25/30.5,
  week = 365.25/7,
  day = 365.25,
  hour = 365.25*24,
  min = 365.25*24*60,
  sec = 365.25*24*60*60)

test_inputs <- list(
  list(conversions = conversions,
    ages = c(0.000001, 0.00001, 0.0001, 0.001, 0.01, 0.1, 1, 10)),
  # test example input
  list(conversions = conversions, 
    ages = 1*10 ^ (-6:1)),
  # test random input
  list(conversions = conversions, 
    ages = 1*10 ^ runif(5, min = -6, max = 2)),
  # test case len(ages) == 1
  list(conversions = conversions, 
    ages = 1*10 ^ runif(1, min = -6, max = 2)),
  # test long input
  list(conversions = conversions, 
    ages = 1*10 ^ runif(5000, min = -6, max = 2)))

list(
  test_inputs = test_inputs,
  test_timeouts = 0.1,
  solution = quote({
    m <- floor(ifelse((m <- ages %*% t(conversions)) >= 1, m, NA))
    i <- apply(m, 1, Position, f = Negate(is.na))
    v <- setNames(Map("[", split(m, row(m)), i), colnames(m)[i])
    paste0(v, " ", names(v), ifelse(v>1, "s", ""), " old")
  }),
  quoted = TRUE)

# already in environment:
#   ages (numeric vector; 0.000001 <= value <= 100; 1 <= length <= 10,000)
#   conversions (named numeric vector of unit conversions [n/year])

print(ages)
print(round(conversions))

dgkf/riddlr documentation built on Oct. 24, 2020, 3:52 a.m.