[R] Symbol/String comparison in R
Ebert,Timothy Aaron
tebert @end|ng |rom u||@edu
Thu Apr 14 03:37:14 CEST 2022
https://en.wikipedia.org/wiki/ASCII
There is a table towards the end of the document. Some of the other pieces may be of interest and/or relevant.
Tim
-----Original Message-----
From: R-help <r-help-bounces using r-project.org> On Behalf Of Kristjan Kure
Sent: Wednesday, April 13, 2022 10:06 AM
To: r-help using r-project.org
Subject: [R] Symbol/String comparison in R
[External Email]
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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