7:17 p.m.
Dear Gretl Community,
How can I use quotation marks inside a Gretl function that deals with
strings? Suppose a I have a text file like this one:
<text file>
O meu nome é "Severino",
como não tenho outro de pia.
Como há muitos "Severinos",
que é santo de romaria,
deram então de me chamar
"Severino de Maria".
<text file>
Now I would like to use readfile and strsub functions to read the file and
replace the quotation marks (" ") with asterisks (* *):
<hansl>
string Texto = readfile("Morte e Vida SeverinaSeverino.txt")
strinf Novo_Texto = strsub(Texto, """, "*")
<hansl>
Best regards,
Henrique
7:43 p.m.
Em 18 de maio de 2015, Sven escreveu:
Am 18.05.2015 um 21:17 schrieb Henrique Andrade:
Dear Sven, thanks for your attention!
I tested with the resub and I got no success. Take a look at the following
code:
string Texto = sprintf("\n\
O meu nome é 'Severino',\n\
como não tenho outro de pia.\n\
Como há muitos 'Severinos',\n\
que é santo de romaria,\n\
deram então de me chamar\n\
'Severino de Maria'.")
string Texto1 = strsub(Texto, "'", "*")
print Texto1
string Texto2 = regsub(Texto, "'", "\"")
print Texto2
We can generate Texto1, but Texto2 fails.
Best,
Henrique
10:18 p.m.
Hi Henrique,
I think you found a bug. The following code works fine:
string Texto2 = regsub(Texto, "[']", "\\")
print Texto2
But only works for the "\\", of you try with other escaped chars it fail.
As an example of Perl regex, the following Unix command gives the expected
result.
sed "s/[']/\"/g" "Morte e Vida SeverinaSeverino.txt"
Hélio
On Mon, May 18, 2015 at 8:43 PM, Henrique Andrade <henrique.coelho(a)gmail.com
wrote:
11:02 p.m.
After digging down the code, there is a solution to your problem. You have
to use the octal representation for the replacing character. The following
code will replace single quotes for double quotes:
string Texto2 = regsub(Texto, "[']", "\0042")
print Texto2
---
Leaving the regsub code as is, maybe the documentation should be improved.
Get it from
https://developer.gnome.org/glib/stable/glib-Perl-compatible-regular-expr...
If Allin or Jack want me to have a try to improve the regex processing I
could have a go.
Hélio
On Mon, May 18, 2015 at 11:18 PM, Hélio Guilherme <helioxentric(a)gmail.com>
wrote:
4:08 p.m.
On Tue, 19 May 2015, Sven Schreiber wrote:
There may be something going on with GLib versions here. On Linux with
GLib 2.44.0 the following works fine:
<hansl>
string s1 = sprintf("string with \"quoted\" bit")
print s1
string s2 = regsub(s1, "\"", "*")
print s2
</hansl>
<output>
? string s1 = sprintf("string with \"quoted\" bit")
Generated string s1
? print s1
string with "quoted" bit
? string s2 = regsub(s1, "\"", "*")
Generated string s2
? print s2
string with *quoted* bit
</output>
Allin
4:15 p.m.
Am 19.05.2015 um 18:08 schrieb Allin Cottrell:
On Tue, 19 May 2015, Sven Schreiber wrote:
Yes, but if I do it the other way around:
<hansl>
string s1 = sprintf("string with *quoted* bit")
print s1
string s2 = regsub(s1, "\*", "\"")
print s2
</hansl>
then I get an error saying \" is an unknown escape sequence. Or am I
missing something?
thanks,
sven
11:47 p.m.
Dear Hélio, Riccardo, Sven and Allin,
Thank you so much for your help and efforts to help me find a way to solve
my problem!
Best regards,
Henrique
8:35 a.m.
On Tue, 19 May 2015, Sven Schreiber wrote:
This is subtle. To get the last regsub above (where the replacement
text is a double-quote) to work you have to pass a string that
contains nothing but a double-quote. This is the same as for use of
sed via the *nix shell, except in that context you type a backslash
before the double-quote so that the shell will pass a literal
double-quote to sed (sed itself won't see the backslash).
In hansl, the only way to create a string that contains nothing but a
double-quote is to use printf(). Hence the fact that Jack's approach
works:
string dq = sprintf("\"")
string s2 = regsub(s1, "\*", dq)
In other words, there's no error in GLib's regexp code, and there
isn't really an error in gretl either -- it's just that at some point
in the past we decided not to mess with escapes in the straight
definition of a string literal, but only via printf.
Allin
9:16 a.m.
Am 20.05.2015 um 10:35 schrieb Allin Cottrell:
On Tue, 19 May 2015, Sven Schreiber wrote:
Ok, but then I don't really understand the need for the co-existence of
strsub() and regsub(). Or to put it differently, why not simply feed the
string arguments in regsub() always through sprintf(), such that
effectively any call regsub(a, b, c) would be handled as
regsub(sprintf(a), sprintf(b), sprintf(c)). Then the distinction between
strsub() and regsub() would be clearcut.
In any case, currently the help text for regsub seems a little
misleading ("The arguments match and repl are interpreted as Perl-style
regular expressions.")
Also, as a lame repeated comment, could the error message somehow give
the user a hint about the underlying problem? For example if the message
said "escape sequences are only handled in the printf() / sprintf()
functions", then the user could replace the literal string, as in:
string s2 = regsub(s1, "\*", sprintf("\""))
(tested and working for s1 == "hu * hu")
thanks,
sven
1:40 p.m.
On Wed, 20 May 2015, Sven Schreiber wrote:
They are quite distinct, regardless of how the regular expressions are
constructed on input. Lots of symbols have a special meaning in regsub
but not in strsub (for example, '.').
That's a cute idea (for strings b and c, anyway), and it works nicely
for the few examples we've been looking at, but I'm afraid it doesn't
work in general. For example, "%" has a special meaning in sprintf
which will break any match/replace strings that are passed it.
<hansl>
string s1 = "20%x 30%y"
string s2 = regsub(s1, sprintf("%."), sprintf("percent"))
</hansl>
The above works fine without the sprintf calls, but with them it will
choke on "%.".
Allin
10:23 a.m.
On Mon, 18 May 2015, Henrique Andrade wrote:
Here's a workaround:
<hansl>
string Texto = sprintf("\n\
O meu nome é 'Severino',\n\
como não tenho outro de pia.\n\
Como há muitos 'Severinos',\n\
que é santo de romaria,\n\
deram então de me chamar\n\
'Severino de Maria'.")
string dq = sprintf("\"")
string Texto2 = regsub(Texto, "'", dq)
print Texto2
</hansl>
-------------------------------------------------------
Riccardo (Jack) Lucchetti
Dipartimento di Scienze Economiche e Sociali (DiSES)
Università Politecnica delle Marche
(formerly known as Università di Ancona)
r.lucchetti(a)univpm.it
http://www2.econ.univpm.it/servizi/hpp/lucchetti
-------------------------------------------------------
10:36 a.m.
On Tue, 19 May 2015, Riccardo (Jack) Lucchetti wrote:
Ah, by the way:
<hansl>
string Texto2 = strsub(Texto, "'", dq)
</hansl>
would also work.
-------------------------------------------------------
Riccardo (Jack) Lucchetti
Dipartimento di Scienze Economiche e Sociali (DiSES)
Università Politecnica delle Marche
(formerly known as Università di Ancona)
r.lucchetti(a)univpm.it
http://www2.econ.univpm.it/servizi/hpp/lucchetti
-------------------------------------------------------
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14 comments
5 participants
participants (5)
-
Allin Cottrell -
Henrique Andrade -
Hélio Guilherme -
Riccardo (Jack) Lucchetti -
Sven Schreiber