Creating vector based on whether dataframe values are divisible by ten

February 6, 2022

library(babynames)

I am looking to make a vector of all decade marker years AKA years in the babynames package that are divisible by 10.

range(babynames$year)

told me the years in the set are 1880-2017 and I made the following solution

c(seq(from=1880,to=2017,10))

However if the range of babynames did not begin on a number that ended with 10 this example would not work. So now I am looking to find a solution that finds all the decade markers (1890,1900,1910…) between numbers if the first is for ex. 1881

I expect this is possible by checking whether the year between 1881-2017 is divisible by 10 resulting in an integer, and if it is, listing it. How do I do this?

Something like this pseudo code

for (i in 1881:2017) {
  if (is.integer(i/10)==TRUE)
  c(i)

>Solution :

Using the modulo operator %% which gives the remainder of a division you could do:

library(babynames)

years <- sort(unique(babynames$year))
years[years %% 10 == 0]
#>  [1] 1880 1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010