Re: transform

From:

"John Carson" <jcarson_n_o_sp_am_@netspace.net.au>

Newsgroups:

comp.lang.c++

Date:

Mon, 26 Feb 2007 10:35:14 +1100

Message-ID:

<45e21d3a$0$1155$61c65585@un-2park-reader-01.sydney.pipenetworks.com.au>

"John Carson" <jcarson_n_o_sp_am_@netspace.net.au> wrote in message
news:45e1a3a3$0$1153$61c65585@un-2park-reader-01.sydney.pipenetworks.com.au

"Chris Roth" <czr137@mail.usask.ca> wrote in message
news:ers6av$ujp$1@webmail.usask.ca

I'm just starting out using the algorithms in c++ std library.

I have a vector of vectors (v) and want to get a slice at some index.
ex. If v held two vectors, v1 and v2:
v1 = 1 2 3 4 5 6
v2 = 7 7 8 8 9 9
the slice at position 3 would be 3 8 (v1(3) and v2(3)).

I think it is possible to use transform to make the slice matrix, but
I'm having trouble with the final argument:

vector< vector<double> > v;
// populate v

vector<double> slice;

transform( v.begin(), v.end(), slice.begin(), ??? );

What goes in ???
I have tried std::vector<double>::at(), but it didn't work.

Transform produces the same number of elements as output as there is
input. You want less elements as output.

Oops. The number of elements here is two in each case, since you are
iterating over the two vector elements of the enclosing vector. Scratch that
comment.

--
John Carson