Using Gapminer set, i have to get an answer

[Daniel1_1]

Hello, i was trying to the my calculation to get Korea, Rep's max population and year that's matching to max populaton.
Therefore i made like that like
apply(gapminder[gapminder$country=="Korea, Rep.",c("pop","year")],2,max)
But i think...it's something wrong....
Can i get an right answer or the solution to make it
Help me
Thanks
I think the point is separation between pop and year.
But i don't know the way...

[mattwarkentin]

Hi @Daniel1_1,

Does this give you the information you are looking for:

library(dplyr)

gapminder::gapminder %>% 
  filter(country == 'Korea, Rep.') %>%
  arrange(desc(pop)) %>% 
  slice(1)
#> # A tibble: 1 x 6
#>   country     continent  year lifeExp      pop gdpPercap
#>   <fct>       <fct>     <int>   <dbl>    <int>     <dbl>
#> 1 Korea, Rep. Asia       2007    78.6 49044790    23348.

^{Created on 2019-12-12 by the reprex package (v0.3.0)}

[EconProf]

Your code gives the right answer for the wrong reason. apply() will use the chosen function on each column (or row), so you are finding the max of the year column and the max of the pop column. In this case, the highest value for year is 2007, which is the last year in the data set, so it also happens to be the year with the highest population. There is no reason to use apply() for this exercise.

My suggestion is to use which.max(pop), which identifies the row (by number) with the highest value of pop. If you need to use base R, this code would work

library(gapminder)
korea <- gapminder[gapminder$country == "Korea, Rep.", c("year", "pop")]
korea[which.max(korea$pop), ]
#> # A tibble: 1 x 2
#>    year      pop
#>   <int>    <int>
#> 1  2007 49044790

^{Created on 2019-12-13 by the reprex package (v0.3.0)}

If you can use the tidyverse, this code would also work

library(dplyr)
library(gapminder)

gapminder %>% 
  filter(country == "Korea, Rep.") %>% 
  select(year, pop) %>% 
  slice(which.max(pop))
#> # A tibble: 1 x 2
#>    year      pop
#>   <int>    <int>
#> 1  2007 49044790

^{Created on 2019-12-13 by the reprex package (v0.3.0)}