Blocks of code should be set as style "Formatted" like this. Code: Cpp Hello, I want to extract columns from file2 to file3 by matching ids between file1 and file2. The extracted columns should be in same order as file1 ids. for example: file1.txt 1823 607 R2A9 802 771 file2.txt 1823 1 2 4 22 11 4 29 607 12 3 3 R2A9 34 4 9 D33 2 1 0 802 30 8 1 771 3 0 9 3RE 6 3 1 output file3.txt should be printed in this way 1823 1 2 4 607 12 3 3 R2A9 34 4 9 802 30 8 1 771 3 0 9 Please suggest me something. Thanks, /S
Code: /* file1.txt 1823 607 R2A9 802 771 file2.txt 1823 1 2 4 22 11 4 29 607 12 3 3 R2A9 34 4 9 D33 2 1 0 802 30 8 1 771 3 0 9 3RE 6 3 1 output file3.txt should be printed in this way 1823 1 2 4 607 12 3 3 R2A9 34 4 9 802 30 8 1 771 3 0 9 */ #include <fstream> #include <string> #include <vector> #include <map> void ExtractCol() { do { /* * Open file one collects its data line-by-line in vector of string. */ std::fstream file; file.open("file1.txt", std::ios::in); if(!file) { break; } std::vector<std::string> file1Data; std::string line(""); while(!file.eof()) { line.clear(); std::getline(file, line, '\n'); file1Data.push_back(line); } file.close(); /* * Open file2 and collects its data in string-string map. * the first word of each line in file 2 will acts as a * key for the map and rest part of each line will be * stored as its value. */ file.open("file2.txt", std::ios::in); if(!file) break; typedef std::pair<std::string, std::string> strstrpair; typedef std::map<std::string, std::string> strstrmap; strstrmap file2Data; while(!file.eof()) { line.clear(); std::getline(file, line, '\n'); size_t found = line.find_first_of(" "); file2Data.insert(strstrpair(line.substr(0, found), line.substr(found+1, line.length() - 1))); } file.close(); /* * Prepare data for file 3. * We need to put those lines of file 2 in file3 which * is common in both file1 and file2's starting word. */ std::string file3Data(""); for(std::vector<std::string>::iterator it = file1Data.begin(); it != file1Data.end(); ++it) { strstrmap::iterator it2; it2 = file2Data.find(*it); if(it2 != file2Data.end()) { file3Data.append(*it); file3Data.append(" "); file3Data.append(it2->second); file3Data.append("\n"); } } /* * finally create file 3. */ file.open("file3.txt", std::ios::out|std::ios::trunc); if(!file) break; file.write(file3Data.c_str(), file3Data.length()); file.close(); }while(false); }
Hello Sheen, Perl could solve this problem with code like that below. Notice the $trie, (pronounced 'try'), variable. Starting with perl 5.10 I believe, perl uses a trie to search for alternating strings. It is Big O1 or constant and scales well. My code builds a trie of the alternating values in file1. Then, it reads file 2 and if the beginning of any line matches the trie, it prints out that line from file 2. If you want that in a third file, simply open a file for wring and print there. My example just prints to STDOUT, (the console window). Chris Code: #!/usr/bin/perl use strict; use warnings; use 5.014; my $file1 = <<EOF; 1823 607 R2A9 802 771 EOF my $file2 = <<EOF; 1823 1 2 4 22 11 4 29 607 12 3 3 R2A9 34 4 9 D33 2 1 0 802 30 8 1 771 3 0 9 3RE 6 3 1 EOF my $trie; { local $/; open my $fh, "<", \$file1; $trie = join "|", split /\n/, <$fh>; close $fh or die $!; } open my $fh, "<", \$file2; /^(?:$trie)/ && print while <$fh>; close $fh or die $!; The output is: Code: C:\Old_Data\perlp>perl t.pl 1823 1 2 4 607 12 3 3 R2A9 34 4 9 802 30 8 1 771 3 0 9
