Re: (silly?) speed comparisons

[mk]

Rajanikanth Jammalamadaka wrote:

Try using a list instead of a vector for the C++ version.

Well, it's even slower:

$ time slice4

real 0m4.500s
user 0m0.015s
sys 0m0.015s


Time of execution of vector version (using reference to a vector):

$ time slice2

real 0m2.420s
user 0m0.015s
sys 0m0.015s

Still slower than Python!


Source, using lists in C++:

---- slice4.c++ ----
#include <list>
#include <iostream>
#include <string>

using namespace std;

list<stringmove _slice(list<str ing>& slist, int start, int stop, int dest)
{
int idx;
if( dest stop)
idx = dest - (stop - start);
else
idx = dest;

list<stringfrag ;

int i;
list<string>::i terator startiter;
list<string>::i terator enditer;

startiter = slist.begin();

for (i = 0; i < start; i++)
startiter++;
enditer = startiter;

// copy fragment
for (i = start; i < stop; i++)
{
frag.push_back( *enditer);
enditer++;
}

// delete frag from the slist
slist.erase( startiter, enditer );

// insert frag into slist at idx
startiter = slist.begin();
for (i = 0; i < idx; i++)
startiter++;
slist.insert( startiter, frag.begin(), frag.end());

/* cout << "frag " << endl;
for (startiter = frag.begin(); startiter != frag.end(); startiter ++)
cout << *startiter << " ";
cout << endl;

cout << "slist " << endl;
for (startiter = slist.begin(); startiter != slist.end(); startiter++)
cout << *startiter << " ";
cout << endl;*/

return slist;
}


int main(int argc, char* argv)
{
list<stringslic e;
string u = "abcdefghij ";
int pos;
for (pos = 0; pos < u.length(); pos++)
slice.push_back (u.substr(pos,1 ));
int i;
for (i = 0; i<1000000; i++)
move_slice(slic e, 6, 7, 7);

}

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Source, using reference to a vector:

---- slice2.c++ ----
#include <vector>
#include <iostream>
#include <string>

using namespace std;

vector<stringmo ve_slice(vector <string>& vec, int start, int stop, int
dest)
{
int idx = stop - start;
vector<stringfr ag;
for (idx = start; idx < stop; idx++)
frag.push_back( vec.at(idx));
if( dest stop)
idx = dest - (stop - start);
else
idx = dest;
vec.erase( vec.begin() + start, vec.begin() + stop);
vec.insert( vec.begin() + idx, frag.begin(), frag.end());
return vec;
}


int main(int argc, char* argv)
{
vector<stringsl ice;
string u = "abcdefghij ";
int pos;
for (pos = 0; pos < u.length(); pos++)
slice.push_back (u.substr(pos,1 ));
int i;
for (i = 0; i<1000000; i++)
move_slice(slic e, 6, 7, 7);

}

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