is anyone aware of generalized transform, for_each?

[er]

hi,

is anyone aware of a library that generalizes transform, for_each?
e.g.

transform(
vec1.begin(),
vec1.end(),
vec2.begin(),
vec3.begin(),
vec4.begin(),
back_inserter(v ec5),
op
)//where op is a 4-ary function

[John Harrison]

er wrote:

hi,

is anyone aware of a library that generalizes transform, for_each?
e.g.

transform(
vec1.begin(),
vec1.end(),
vec2.begin(),
vec3.begin(),
vec4.begin(),
back_inserter(v ec5),
op
)//where op is a 4-ary function

I've just written one,

template <class II, class OI, class F4>
OI transform(II first, II last, II first2, II first3, II first4, OI
dest, F4 func)
{
while (first != last)
{
*dest = func(*first, *first2, *first3, *first4);
++first;
++first2;
++first3;
++first4;
++dest;
}
return dest;
}

That will be $8000 please.

john

[red floyd]

John Harrison wrote:

er wrote:

>hi,

is anyone aware of a library that generalizes transform, for_each?
e.g.

transform(
vec1.begin(),
vec1.end(),
vec2.begin(),
vec3.begin(),
vec4.begin(),
back_inserter(v ec5),
op
)//where op is a 4-ary function

I've just written one,

template <class II, class OI, class F4>
OI transform(II first, II last, II first2, II first3, II first4, OI
dest, F4 func)

template <typename II1, typename II2, typename II3, typename II4,
typename OI, typename F4>
OI transform(II1 first, II1 last, II2 first2, II3 first3, II4 first4,
OI dest, F4 func)

{
while (first != last)
{
*dest = func(*first, *first2, *first3, *first4);
++first;
++first2;
++first3;
++first4;
++dest;
}
return dest;
}

Which allows for merging of different iterator types (list, vector,
set...) as well as different types for the values (int, float, double...)

[er]

On Sep 27, 12:13 pm, red floyd <no.s...@here.d udewrote:

John Harrison wrote:

er wrote:

hi,

is anyone aware of a library that generalizes transform, for_each?
e.g.

transform(
vec1.begin(),
vec1.end(),
vec2.begin(),
vec3.begin(),
vec4.begin(),
back_inserter(v ec5),
op
)//where op is a 4-ary function

I've just written one,

template <class II, class OI, class F4>
OI transform(II first, II last, II first2, II first3, II first4, OI
dest, F4 func)

template <typename II1, typename II2, typename II3, typename II4,
typename OI, typename F4>
OI transform(II1 first, II1 last, II2 first2, II3 first3, II4 first4,
OI dest, F4 func)

{
while (first != last)
{
*dest = func(*first, *first2, *first3, *first4);
++first;
++first2;
++first3;
++first4;
++dest;
}
return dest;
}

Which allows for merging of different iterator types (list, vector,
set...) as well as different types for the values (int, float, double...)

yes, thank you both, but this is generalized in type, not in
dimension. i should have made that clear in the first post, and
replace 4 by an arbitrary N. i'm aware that this is no trivial
task...hence my posting here.

[Jeff F]

"er" <er***********@ gmail.comwrote in message
news:11******** **************@ n39g2000hsh.goo glegroups.com.. .

hi,

is anyone aware of a library that generalizes transform, for_each?
e.g.

transform(
vec1.begin(),
vec1.end(),
vec2.begin(),
vec3.begin(),
vec4.begin(),
back_inserter(v ec5),
op
)//where op is a 4-ary function

See http://www.boost.org/libs/iterator/d..._iterator.html. Quote:

std::vector<dou ble>::const_ite rator beg1 = vect_of_doubles .begin();
std::vector<dou ble>::const_ite rator end1 = vect_of_doubles .end();
std::vector<int >::const_iterat or beg2 = vect_of_ints.be gin();
std::vector<int >::const_iterat or end2 = vect_of_ints.en d();

std::for_each(b eg1, end1, func_0());
std::for_each(b eg2, end2, func_1());
These two iterations can now be replaced with a single one as follows:

std::for_each(
boost::make_zip _iterator(
boost::make_tup le(beg1, beg2)
),
boost::make_zip _iterator(
boost::make_tup le(end1, end2)
),
zip_func()
);
struct zip_func :
public std::unary_func tion<const boost::tuple<co nst double&, const int&>&,
void>
{
void operator()(cons t boost::tuple<co nst double&, const int&>& t) const
{
m_f0(t.get<0>() );
m_f1(t.get<1>() );
}

private:
func_0 m_f0;
func_1 m_f1;
};
Jeff Flinn

[er]

On Sep 27, 7:59 pm, "Jeff F" <norepl...@plea se.comwrote:

"er" <erwann.rog...@ gmail.comwrote in message

news:11******** **************@ n39g2000hsh.goo glegroups.com.. .

hi,

is anyone aware of a library that generalizes transform, for_each?
e.g.

transform(
vec1.begin(),
vec1.end(),
vec2.begin(),
vec3.begin(),
vec4.begin(),
back_inserter(v ec5),
op
)//where op is a 4-ary function

Seehttp://www.boost.org/libs/iterator/doc/zip_iterator.ht ml. Quote:

std::vector<dou ble>::const_ite rator beg1 = vect_of_doubles .begin();
std::vector<dou ble>::const_ite rator end1 = vect_of_doubles .end();
std::vector<int >::const_iterat or beg2 = vect_of_ints.be gin();
std::vector<int >::const_iterat or end2 = vect_of_ints.en d();

std::for_each(b eg1, end1, func_0());
std::for_each(b eg2, end2, func_1());
These two iterations can now be replaced with a single one as follows:

std::for_each(
boost::make_zip _iterator(
boost::make_tup le(beg1, beg2)
),
boost::make_zip _iterator(
boost::make_tup le(end1, end2)
),
zip_func()
);
struct zip_func :
public std::unary_func tion<const boost::tuple<co nst double&, const int&>&,
void>
{
void operator()(cons t boost::tuple<co nst double&, const int&>& t) const
{
m_f0(t.get<0>() );
m_f1(t.get<1>() );
}

private:
func_0 m_f0;
func_1 m_f1;};

Jeff Flinn

thanks!