The problem file below works with other words except "change".
Webwork interprets "change" as "chan ge" for some reason and all
replies are marked wrong.
DOCUMENT();
loadMacros(
"PGstandard.pl",
"PGML.pl",
"MathObjects.pl",
"PGcourse.pl",
"parserNumberWithUnits.pl",
"contextArbitraryString.pl",
"parserPopUp.pl",
"contextInequalities.pl",
);
TEXT(beginproblem());
$showPartialCorrectAnswers = 1;
$menu = PopUp(["select one", "yes", "no"], "yes");
@string_answers = ("change");
$strings = Compute($string_answers[0])->cmp(checker => sub {
my ($temp, $response, $temp) = @_;
$response = $response->value;
foreach (@string_answers) {
if (lc($response) eq lc($_)) {
return 1;
}
}
return 0;
});
######################################################################
Context("ArbitraryString");
BEGIN_PGML
What one word refers to triangles containing right angles?
[____________]{$strings}
END_PGML
######################################################################
ENDDOCUMENT();
You are missing the
Context("ArbitraryString");
in order to activate ArbitraryString context.
Davide
Thanks. I added Context("ArbitraryString"); and it still interprets "change" as "chan ge".
Here is what Webwork says...
I accessed the problem by viewing it with the "Library Browser". I ran
it under CAPA and Local Problems libraries.
DOCUMENT();
loadMacros(
"PGstandard.pl",
"PGML.pl",
"MathObjects.pl",
"PGcourse.pl",
"parserNumberWithUnits.pl",
"contextArbitraryString.pl",
"parserPopUp.pl",
"contextInequalities.pl",
);
TEXT(beginproblem());
$showPartialCorrectAnswers = 1;
@string_answers = ("change");
$strings = Compute(@string_answers[0])->cmp(checker => sub {
my ($answers, $response, $temp) = @_;
foreach (@string_answers) {
if (lc($response) eq lc($_)) {
return 1;
}
}
return 0;
});
Context("ArbitraryString");
BEGIN_PGML
What one word describes what calculus is about?
[____________]{$strings}
END_PGML
ENDDOCUMENT();
Here is what Webwork says...
| Entered | Answer Preview | Result |
|---|---|---|
| chan ge | chan | incorrect |
I accessed the problem by viewing it with the "Library Browser". I ran
it under CAPA and Local Problems libraries.
DOCUMENT();
loadMacros(
"PGstandard.pl",
"PGML.pl",
"MathObjects.pl",
"PGcourse.pl",
"parserNumberWithUnits.pl",
"contextArbitraryString.pl",
"parserPopUp.pl",
"contextInequalities.pl",
);
TEXT(beginproblem());
$showPartialCorrectAnswers = 1;
@string_answers = ("change");
$strings = Compute(@string_answers[0])->cmp(checker => sub {
my ($answers, $response, $temp) = @_;
foreach (@string_answers) {
if (lc($response) eq lc($_)) {
return 1;
}
}
return 0;
});
Context("ArbitraryString");
BEGIN_PGML
What one word describes what calculus is about?
[____________]{$strings}
END_PGML
ENDDOCUMENT();
You must put the
Davide
Context() statement before you create the $strings, because MathObjects retain the context in which they were created.Davide
Davide
Wow thanks. I never would have caught that. It works! Thanks!
Can I ask you one last Perl question? I can convert to lowercase with lc
but when I try to remove whitespace from the ends of the student answer
it appears to be ignored...
Context("ArbitraryString");
@string_answers = ("change");
$strings = Compute($string_answers[0])->cmp(checker => sub {
my ($temp1, $response, $temp2) = @_;
$response =~ s/^\s+|\s+$//g;
$response = lc($response);
foreach (@string_answers) {
if ($response eq lc($_)) {
return 1;
}
}
return 0;
});
The line: "$response =~ s/^\s+|\s+$//g;" doesn't seem to change $response.
Do you know why that wouldn't work!
cs
Wow thanks. I never would have caught that. It works! Thanks!
Can I ask you one last Perl question? I can convert to lowercase with lc
but when I try to remove whitespace from the ends of the student answer
it appears to be ignored...
Context("ArbitraryString");
@string_answers = ("change");
$strings = Compute($string_answers[0])->cmp(checker => sub {
my ($temp1, $response, $temp2) = @_;
$response =~ s/^\s+|\s+$//g;
$response = lc($response);
foreach (@string_answers) {
if ($response eq lc($_)) {
return 1;
}
}
return 0;
});
The line: "$response =~ s/^\s+|\s+$//g;" doesn't seem to change $response.
Do you know why that wouldn't work!
cs
This is because of how PG handles backslashes. In order to make it easier to include TeX notation in your problem, PG automatically doubles all backslashes before evaluating the expression, so that you can write
BEGIN_TEXT
What is \(\lim_{x\to\infty} \frac{1}{x}\) ?
END_TEXT
rather than having to use
BEGIN_TEXT
What is \\(\\lim_{x\\to\\infty} \\frac{1}{x}\\) ?
END_TEXT
which would make TeX much harder to write. But it has the side effect of making regular expressions more difficult to write, because
$response =~ s/^\s+|\s+$//g;
becomes
$response =~ s/^\\s+|\\s+$//g;
without your knowing it. This is why it isn't matching anything.
PG does provide a means of getting a single backslash, but it is ugly: you must use ~~ if I recall correctly. So you would need your regular expression to be
$response =~ s/^~~s+|~~s+$//g;
if you include it in a .pg file.
Davide
If you move the custom grader to a .pl macro file at some point the convention
changes back to pure perl. You need to use double backslashes in TeX expressions and you must use single backslashes in regular expressions and to
create references such as \@array.
This frequently gives me pause for a few minutes when I move a routine that
was embedded in a .pg problem to a macro .pl file for general use. It stops working until I remember to use the appropriate syntax for that file.
The rationale is that in .pg files you write a lot of TeX but not a lot of fancy perl so not having to type double backslashes is convenient, whereas in the macro files you write more perl than TeX.
THANKS!! Finally SUCCESS!!! With ~~'s I can now strip whitespace and handle
differences in capitalization. Hopefully others will find this thread and use my custom grader as well.
Thanks again,
Chris
differences in capitalization. Hopefully others will find this thread and use my custom grader as well.
Thanks again,
Chris