将标签从一个文件映射到另一个文件

Question

我有两个文件

档案A：

John
Janice
Carry
Ethan

档案B：

2 Ronny
1 Michelle
2 John
2 Janice
10 Carry
1 Ethan

我想从文件B到文件A获取第一列（数字），以便我可以拥有此类文件A

2 John
2 Janice
10 Carry
1 Ethan

我怎样才能使用bash？

Answer 1

以下awk单行代码可以解决问题：

$ awk 'FNR==NR{a[$2]=$1;next}($0 in a){print a[$0],$0}' file2 file1 
2 John
2 Janice
10 Carry
1 Ethan

Answer 2

您可以尝试Perl：

open( A, "<", "A.txt" ) or die "Cannot open A.txt\n";  # open A.txt for reading
open( B, "<", "B.txt" ) or die "Cannot open B.txt\n";  # open B.txt for reading
chomp( my @A = <A> );                                  # get rid of newlines
while(my $bline = <B>){                             # iterate B.txt
    chomp( $bline );                                    # get rid of newline
    @ha = split /\s+/, $bline;                          # split to get 2nd field (name)
    if ( grep{ /$ha[1]/ } @A ) {                        # if 2nd field found in A array
        print $bline . "\n";            
    }       
}
close( A );                                            # close A file descriptor
close( B );                                            # close B file descriptor