R Character and Date Type Comparison-CodePudding

I'm wondering why does date of character type still act as a Date type in R.

For example:

x <- "2020-01-15"
y <- "2020-01-29"

x < y // *returns true*
x >= 2020 // *returns true*

Is there some auto type conversion in the background?

CodePudding user response：

No, they are evaluated as character, and you can compare characters as well.

'a' < 'b'
# [1] TRUE

Note:

100 < 20
# [1] FALSE

'100' < '20'
# [1] TRUE

CodePudding user response：

Strings are compared lexicographicaly in R.

So the only reason x < y is because the second last character of x is 1, but in y it's 2, so therefore x is smaller than y.

For string comparison of substrings of a string, i.e. 2020 is a substring of 2020-01-05, the longer string would be the bigger string in lexicographical comparison. Therefore obviously the second case gives TRUE.