296 lines
7.9 KiB
C++
296 lines
7.9 KiB
C++
//Hidden Lines work
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#include <iostream>
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#include <set>
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#include <string>
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#include <fstream>
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#include <limits>
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#include <math.h>
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#include <utility>
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#include <algorithm>
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#include "gnuplot-iostream.h"
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#include "HiddenLines.h"
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HL::HL()
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{
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//Read from CSV and construct the problem from the given lines
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lines = construct_HWprob();
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}
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//Print the solution and convert the double::max and double::lowest to inf strings
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void print_sol(std::vector<Line>& lines){
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for(auto itr = lines.begin(); itr != lines.end(); itr++){
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Line line = *itr;
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double start_range = line.get_vis_start();
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std::string start_print = std::to_string(start_range);
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if(start_range == std::numeric_limits<double>::lowest())
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start_print = "-inf";
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double stop_range = line.get_vis_end();
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std::string stop_print = std::to_string(stop_range);
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if(stop_range == std::numeric_limits<double>::max())
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stop_print = "inf";
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if (start_range == stop_range)
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continue;
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std::cout << "Line ID " << line.get_id() << " visible from x=" <<
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start_print << " to x=" << stop_print << std::endl;
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}
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}
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//Divide and Conquer Strategy using recursive call to divide ls and merge using merge()
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std::vector<Line> HL::gen_sol(std::vector<Line>& ls){
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HL inst = *this;
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//Case 1: We need to divide more
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if (ls.size() > 2){
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//Create left and right half sets
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int split = ceil(ls.size()/2);
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std::vector<Line> lh;
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std::vector<Line> rh;
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//Get iterator for the split point location
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auto end_itr = ls.begin();
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std::advance(end_itr, split);
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//Create left half
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for(std::vector<Line>::iterator itr = ls.begin(); itr != end_itr; itr++){
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lh.push_back(*itr);
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}
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//Create right half
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for(std::vector<Line>::iterator itr = end_itr; itr != ls.end(); itr++){
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rh.push_back(*itr);
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}
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//Recursive call
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auto merged = merge(inst.gen_sol(lh), inst.gen_sol(rh));
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return merged;
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}
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//Set with 2 lines is a base case: both are visible at +-inf respectively, and intersection is where they change
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//visibility
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else if (ls.size() == 2){
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//Get non-const iterators to the beginning and end of our vector
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std::vector<Line>::iterator bit = ls.begin();
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std::vector<Line>::iterator eit = std::prev(ls.end());
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Line l1 = *(bit);
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Line l2 = *(eit);
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//Get intersection of our two lines
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double isec = l1.get_isec(l2);
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//If Line 1 has smaller slope, its visibility end in comparison to Line 2 is the intersection. Vice versa for Line 2.
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if (l1.get_slope() < l2.get_slope()){
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l1.set_vis_end(isec);
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*bit = l1;
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l2.set_vis_start(isec);
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*eit = l2;
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}
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else{
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l2.set_vis_end(isec);
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l1.set_vis_start(isec);
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*bit = l1;
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*eit = l2;
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}
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return ls;
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}
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//Set with 1 line: Just return - no comparisons to make at this point.
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else{
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return ls;
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}
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}
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//Read from CSV file to construct this problem. Use std::set to order
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std::vector<Line> HL::construct_HWprob(){
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//Set to hold all our Lines
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std::set<Line> sorted_lines;
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std::vector<Line> lines;
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//Hold our doubles from each line
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std::vector<double> tmp_data;
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std::ifstream data("../data/data.csv");
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if(data.is_open()){
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std::string csvline;
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//Throw header row away
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std::getline(data, csvline);
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while(std::getline(data, csvline, ',')){
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if(!csvline.empty()){
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tmp_data.emplace_back(std::stod(csvline));
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}
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}
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}
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//Close file
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data.close();
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while(!tmp_data.empty()){
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double slope = *tmp_data.begin();
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tmp_data.erase(tmp_data.begin());
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if(tmp_data.empty()){
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std::cout << "Error in CSV file: Number of slope entries does not match the number of y-intercept entries. ";
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std::cout << "Please correct the CSV file and try again." << std::endl;
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exit(-1);
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}
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double ycept = *tmp_data.begin();
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tmp_data.erase(tmp_data.begin());
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Line newline = Line(slope, ycept);
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newline.set_id();
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sorted_lines.insert(newline);
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}
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//Copy set to vector
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std::copy(sorted_lines.begin(), sorted_lines.end(), std::back_inserter(lines));
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//Display Sorted Vector
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std::cout << "---------------Sorted Lines by slope:---------------" << std::endl;
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for(std::vector<Line>::iterator it = lines.begin(); it != lines.end(); it++)
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{
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Line line = *it;
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std::cout << "Line " << line.get_id() << " has slope " << line.get_slope()
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<< " and a y-intercept of " << line.get_ycept() << std::endl;
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if (it == lines.begin()){
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line.set_vis_start(std::numeric_limits<double>::lowest());
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*it = line;
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}
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if (it == (std::prev(lines.end()))){
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line.set_vis_end(std::numeric_limits<double>::max());
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*it = line;
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}
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}
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std::cout << "-----------------------------------------------------" << std::endl;
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return lines;
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}
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//Merge the two halves and set visible start and end points
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std::vector<Line> merge(std::vector<Line> lh, std::vector<Line> rh){
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std::vector<Line> merged;
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//Get non-const iterators to the start of both vectors
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std::vector<Line>::iterator litr = lh.begin();
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std::vector<Line>::iterator ritr = rh.begin();
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while(litr != lh.end() && ritr != rh.end()){
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Line l1 = *litr;
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Line l2 = *ritr;
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//3 Cases: lh slope is less, slopes are equal, and lh slope is greater
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//Case 1:
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if (l1.get_slope() < l2.get_slope()){
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double isec = (l2.get_ycept() - l1.get_ycept())/(l1.get_slope() - l2.get_slope());
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if(isec < l1.get_vis_end()){
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l1.set_vis_end(isec);
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l2.set_vis_start(isec);
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*litr = l1;
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*ritr = l2;
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}
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merged.push_back(l1);
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litr++;
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}
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else if (l1.get_slope() == l2.get_slope() && l1.get_id() != l2.get_id()){
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if (l1.get_ycept() > l2.get_ycept()){
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l2.set_vis_start(0);
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l2.set_vis_end(0);
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*ritr = l2;
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merged.push_back(l1);
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}
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else{
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l1.set_vis_start(0);
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l1.set_vis_end(0);
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*litr = l1;
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merged.push_back(l2);
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}
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litr++;
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ritr++;
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}
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//lh slope > rh
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else{
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double isec = (l2.get_ycept() - l1.get_ycept())/(l1.get_slope() - l2.get_slope());
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if(isec < l1.get_vis_start()){
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l1.set_vis_start(isec);
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l2.set_vis_end(isec);
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*litr = l1;
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*ritr = l2;
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}
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merged.push_back(l2);
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ritr++;
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}
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}
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while (litr != lh.end()){
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merged.push_back(*litr);
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litr++;
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}
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while (ritr != rh.end()){
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merged.push_back(*ritr);
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ritr++;
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}
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//Remove invisible lines
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return remove_invis(merged);
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}
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std::vector<Line> HL::get_lines(){
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return lines;
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}
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/*
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// Line merging process merges the two halves and keeps the order, but does not check for
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// when intersection points fall to the left (more negative) of other intersection points.
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// Need to remove the invisible lines caused by this case.
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*/
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std::vector<Line> remove_invis(std::vector<Line> &merged){
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//Create separate visible line holder
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std::vector<Line> tmp_vis;
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//Since we call this function from a merge, we can safely add two elements.
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tmp_vis.push_back(merged.front());
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merged.erase(merged.begin());
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tmp_vis.push_back(merged.front());
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merged.erase(merged.begin());
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//Loop through the remainder of the original vector
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for(Line &line : merged){
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//Pull out the back two lines
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Line last = tmp_vis.at(tmp_vis.size()-1);
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Line seclast = tmp_vis.at(tmp_vis.size()-2);
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//Intersection of our "known" visible lines vs the intersection of the 2nd to last vis line and the original vec
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double vis_isec = last.get_isec(seclast);
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double merg_isec = line.get_isec(seclast);
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while(merg_isec < vis_isec){
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//Adjust visibility start and end points
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line.set_vis_start(merg_isec);
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seclast.set_vis_end(merg_isec);
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tmp_vis.at(tmp_vis.size()-2) = seclast;
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//line intersects before the last line, and since line slope > last line slope, remove it
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tmp_vis.erase(tmp_vis.begin() + (tmp_vis.size()-1));
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//We only have 1 line visible, no more comparisons needed to see if we have something out of order
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if(tmp_vis.size() == 1)
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break;
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//Otherwise, get our next lines to make sure we don't have something
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last = tmp_vis.at(tmp_vis.size()-1);
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seclast = tmp_vis.at(tmp_vis.size()-2);
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vis_isec = last.get_isec(seclast);
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merg_isec = line.get_isec(seclast);
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}
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tmp_vis.push_back(line);
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}
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return tmp_vis;
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}
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