ostream::operator<< output shows wrong # of values for 2-d array if strides unusual #57
Description
The following sample code produces very odd output to cout using operator<< in the second case (doTranspose == 1):
#include <iostream>
#include <vector>
#include "ndarray.h"
int main() {
// include extra values to avoid reading off the end
std::vector<double> xvec = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20};
int const len = 3;
auto shape1d = ndarray::makeVector(len);
auto strides1d = ndarray::makeVector(1);
// create x = {1, 2, 3} and y = {4, 5, 6}
ndarray::Array<double, 1, 1> x = ndarray::external(xvec.data(), shape1d, strides1d);
ndarray::Array<double, 1, 1> y = ndarray::external(xvec.data() + len, shape1d, strides1d);
std::cout << "x = " << x << std::endl;
std::cout << "y = " << y << std::endl;
for (int doTranspose = 0; doTranspose < 2; ++doTranspose) {
auto xyshape = ndarray::makeVector(2, static_cast<int>(x.getSize<0>()));
std::cout << "\nxyshape = " << xyshape << std::endl;
auto xystrides = ndarray::makeVector(&y[0] - &x[0], static_cast<std::ptrdiff_t>(1));
if (doTranspose) {
std::cout << "transpose xystrides: [[1, 4, 7], [2, 5, 8]]" << std::endl;
xystrides[1] = xystrides[0];
xystrides[0] = 1;
} else {
std::cout << "normal xystrides: [[1, 2, 3], [4, 5, 6]])" << std::endl;
}
std::cout << "xystrides = " << xystrides << std::endl;
ndarray::Array<double, 2, 1> xy = ndarray::external(x.getData(), xyshape, xystrides);
std::cout << "xy.getSize<0>() = " << xy.getSize<0>() << "; xy.getSize<1>() = " << xy.getSize<1>() << std::endl;
for (auto row = 0; row < xy.getSize<0>(); ++row) {
for (int col = 0; col < xy.getSize<1>(); ++col) {
std::cout << "xy[" << row << "][" << col << "] = " << xy[row][col] << std::endl;
}
}
std::cout << "xy = " << xy << std::endl;
}
}
On my system (clang 8.1.0 on macOS) all output is as expected except the final cout<<, which looks screwy and has far too many values:
x = [ 1, 2, 3]
y = [ 4, 5, 6]
xyshape = (2,3,)
normal xystrides: [[1, 2, 3], [4, 5, 6]])
xystrides = (3,1,)
xy.getSize<0>() = 2; xy.getSize<1>() = 3
xy[0][0] = 1
xy[0][1] = 2
xy[0][2] = 3
xy[1][0] = 4
xy[1][1] = 5
xy[1][2] = 6
xy = [[ 1, 2, 3],
[ 4, 5, 6]]
xyshape = (2,3,)
transpose xystrides: [[1, 4, 7], [2, 5, 8]]
xystrides = (1,3,)
xy.getSize<0>() = 2; xy.getSize<1>() = 3
xy[0][0] = 1
xy[0][1] = 4
xy[0][2] = 7
xy[1][0] = 2
xy[1][1] = 5
xy[1][2] = 8
xy = [[ 1, 2, 3, 4, 5, 6, 7, 8, 9],
[ 2, 3, 4, 5, 6, 7, 8, 9, 10]]