[R] regular expression help

[Ashim Kapoor]

Dear All,

My query is:

Do we always need to use perl = TRUE option when doing ignore.case=TRUE?

A small example :

my_text =
"RECOVERY OFFICER-II\nDEBTS RECOVERY TRIBUNAL-III\n  RC No. 162/2015\nSBI
VS RAMESH GUPTA.\n    Dated: 01.03.2016                   Item no.01\n
Present:   Ms. Sonakshi, the proxy counsel for Ms. Usha Singh, the counsel
for ARCIL.\n                None for the CDs.\n  The counsel for the CHFI
submitted that the matter has been assigned to ARCIL and deed of
assignment, application for substituting the name and vakalatnama has been
filed vide diary no. 1454 dated 08.02.2016\nIn the application it has been
prayed that ARCIL may be substituted in place of SBI for the purpose of
further proceedings in the matter. Request allowed.\nThe proxy counsel for
CHFI further requested to issue demand notice thereby mentioning the name
of ARCIL. Request allowed.\nRegistry is directed to issue fresh demand
notice mentioning the name of ARCIL.\nCHFI is directed to file status of
the mortgaged property as well as other assets of the CDs.\nList the case
on 28.03.2016.\n  (SUJEET KUMAR)\nRECOVERY OFFICER-II."

My regular expression is:

parties_present_start_1=
regexpr("\n.*Present.*\n.*\n",my_text,ignore.case=TRUE,perl=T)

parties_present_start_2=
regexpr("\n.*Present.*\n.*\n",my_text,ignore.case=TRUE)

> parties_present_start_1
[1] 138
attr(,"match.length")
[1] 123
attr(,"useBytes")
[1] TRUE
> parties_present_start_2
[1] 20
attr(,"match.length")
[1] 949
attr(,"useBytes")
[1] TRUE
>

Why do I see the correct result only in the first case?

Best Regards,
Ashim

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