function matrix(a, b, c, d, tx, ty) {
return d3.geoTransform({
point: function(x, y) {
const x1 = x;
const y1 = y - height / 2;
const x2 = a * x1 + b * y1;
const y2 = c * x1 + d * y1;
const x3 = x2;
const y3 = y2 + height / 2;
this.stream.point(x3, y3)
}
});
}