[R] Symbol/String comparison in R

[Rui Barradas]

Hello,

This is a locale issue, you are counting on the ASCII table codes but 
that's only valid for the "C" locale.

old_loc <- Sys.getlocale("LC_COLLATE")

"A" < "a"
#> [1] FALSE
"A" > "a"
#> [1] TRUE

Sys.setlocale("LC_COLLATE", locale = "C")
#> [1] "C"

"A" < "a"
#> [1] TRUE
"A" > "a"
#> [1] FALSE

Sys.setlocale("LC_COLLATE", old_loc)
#> [1] "Portuguese_Portugal.1252"


Hope this helps,

Rui Barradas

Às 15:06 de 13/04/2022, Kristjan Kure escreveu:
> Hi!
> 
> Sorry, I am a beginner in R.
> 
> I was not able to find answers to my questions (tried Google, Stack
> Overflow, etc). Please correct me if anything is wrong here.
> 
> When comparing symbols/strings in R - raw numeric values are compared
> symbol by symbol starting from left? If raw numeric values are not used is
> there an ASCII / Unicode table where symbols have values/ranking/order and
> R compares those values?
> 
> *2) Comparing symbols*
> Letter "a" raw value is 61, letter "b" raw value is 62? Is this correct?
> 
> # Raw value for "a" = 61
> a_raw <- charToRaw("a")
> a_raw
> 
> # Raw value for "b" = 62
> b_raw <- charToRaw("b")
> b_raw
> 
> # equals TRUE
> "a" < "b"
> 
> Ok, so 61 is less than 62 so it's TRUE. Is this correct?
> 
> *3) Comparing strings #1*
> "1040" <= "12000"
> 
> raw_1040 <- charToRaw("1040")
> raw_1040
> #31 *30* (comparison happens with the second symbol) 34 30
> 
> raw_12000 <- charToRaw("12000")
> raw_12000
> #31 *32* (comparison happens with the second symbol) 30 30 30
> 
> The symbol in the second position is 30 and it's less than 32. Equals to
> true. Is this correct?
> 
> *4) Comparing strings #2*
> "1040" <= "10000"
> 
> raw_1040 <- charToRaw("1040")
> raw_1040
> #31 30 *34*  (comparison happens with third symbol) 30
> 
> raw_10000 <- charToRaw("10000")
> raw_10000
> #31 30 *30*  (comparison happens with third symbol) 30 30
> 
> The symbol in the third position is 34 is greater than 30. Equals to false.
> Is this correct?
> 
> *5) Problem - Why does this equal FALSE?*
> *"A" < "a"*
> 
> 41 < 61 # FALSE?
> 
> # Raw value for "A" = 41
> A_raw <- charToRaw("A")
> A_raw
> 
> # Raw value for "a" = 61
> a_raw <- charToRaw("a")
> a_raw
> 
> Why is capitalized "A" not less than lowercase "a"? Based on raw values it
> should be. What am I missing here?
> 
> Thanks
> Kristjan
> 
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> 
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