STL library function to partition an interval
I'd like to partition an interval such as [-1.0, 1.0] into a discrete set of equally spaced points with a specified distance or step-size between each point. For example if the step-size is 0.1 my function would return an array:
-1.0, -0.9, -0.8,...., 0.9, 1.0.
Now a way of doing using a vector container is a follows:
vector<double> Range;
double Step = 0.1;
Range.push_back(-1.0);
for(unsigned int开发者_运维问答 i=0; i<int(2.0/Step); i++)
{
Range.push_back(Range.back() + Step);
}
Is there an STL library function I could use?
Check out the generate
function. You will still need to write a function/functor for incrementing, but that is relatively simple and can be reused all the time...
Here is an example using the generate function.
#include <iostream>
#include <algorithm>
#include <vector>
#include <numeric>
#include <math.h>
using namespace std;
// The step interval
const double step = 0.1;
struct stepInterval {
double current;
stepInterval() :
current (-1.0 - step) {
}
double operator()() {
current += step;
return current;
}
} StepInterval;
int main () {
// Calculate the vector size. Add 1 for zero.
const int vectorSize = ceil(2.0 / step) + 1;
// Create the vector
vector<double> myvector (vectorSize);
generate (myvector.begin(), myvector.end(), StepInterval);
cout << "\nmyvector contains:";
for (vector<double>::iterator it=myvector.begin();
it!=myvector.end();
++it) {
cout << " " << *it;
}
cout << endl;
return 0;
}
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