strsplit with invalid regular expression
In R, the source code representation of a special character uses the \ as an escape character to begin a special character sequence. For example, "\n" is a single newline character.
Because backslash has this special meaning, to represent a single backslash character one must escape it: "\\" looks like two backslashes, but in computer memory it is only one character.
R is not the only software that uses the backslash as an escape character: the syntax of regular expressions handled by the regex library also does, but it uses the backslash to SUPPRESS special meaning.
In your first regex you pass a string containing a backslash followed by a left paren, which tells it to treat the ( as a character to be searched for, not a grouping character that defines a substring to "remember" for backreferencing.
In your second regex you tell it that the letter s should be treated as a normal character (which it is anyway), but the ( retains its special meaning that requires a matching ) in the regex.
I suspect that what you wanted was "sin\\(", which gives sin\( to the regex library.
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Bharat Warule <bwarule at gmail.com> wrote:
Hi all,
diff_operator <- "\\("
strsplit(cond, diff_operator)
[[1]] [1] "andsin" "log_angle_1_4)"
diff_operator <- "\\sin("
strsplit(cond, diff_operator)
Error in strsplit(cond, diff_operator) :
invalid regular expression '\sin(', reason 'Missing ')''
When I am going to split with "(" it?s working fine but when i want use
"sin(" this is not working.
I understand that, I am missing something can anybody please point me.
Thanks for your help.
Thanks,
Bharat
-----
Bharat Warule
Pune
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