Question

我试图用列表中每个元组的总和来压缩此列表，然后对其进行过滤，以便只有总和大于0的元组在列表中。此时，使用下面给出的测试代码，在行＆＃34; ----打印0＆＃34;之上的随机元组之后不会打印任何内容。我错过了什么？

 sub filter_random_4_toops_by_sum {
 my ($toops, $thresh) = @_;
 my @toops1 = ();
 @toops1 = $toops;
 my @sorted_toops = ();
 my @sortedReturn = ();
 my @filtered_toops = ();
 @sorted_toops = map{[$_, sum(@$_)]} @toops1;
 @filtered_toops = grep {$_[1]> $thresh} @sorted_toops;
 @sortedReturn = map{$_->[0]} @filtered_toops;
 return \@sortedReturn;
}

测试代码：

sub test_step_4 {
 my($sn)= 1;
 my $toops = gen_random_4_toops(1, 100, 5);
 print "---- random 4-toops:\n";
 foreach(@{$toops}) {
print "toop $sn:\t(@{$_});\n and sum = " . sum(@{$_}) . "\n";
$sn++;
}
 my $thresh = 55;
 print "\n---- random 4-toops filtered by sum above $thresh:\n";
 my $filtered_toops = filter_random_4_toops_by_sum($toops, $thresh);
 $sn = 1;
 foreach(@{$filtered_toops}) {
print "toop $sn:\t(@{$_}); sum = ". sum(@{$_}) . "\n";
$sn++;
 }
}

测试代码应输出：

---- random 4-toops:
toop 1: (49 49 4 64); sum = 166
toop 2: (-2 16 57 76); sum = 147
toop 3: (-94 93 -48 85); sum = 36
toop 4: (19 -47 14 38); sum = 24
toop 5: (-57 80 -60 -35); sum = -72
---- random 4-toops filtered by sum above 0:
toop 1: (19 -47 14 38); sum = 24
toop 2: (-94 93 -48 85); sum = 36
toop 3: (49 49 4 64); sum = 166
toop 4: (-2 16 57 76); sum = 147

相当于我在Python（工作）中尝试做的事情：

def filter_random_4_toops_by_sum(toops, thresh):
    summit = 0
    s = []
    for i in toops:
        # pdb.set_trace()
        summit = 0
        for d in xrange(0,4):
            summit += i[d]
        s.append(summit)
    # pdb.set_trace()
    together = zip(toops, s)
    filtertog = [i for i in together if i[1] > 0]
    toops = [x[0] for x in filtertog]
    return toops

Answer 1

@toops1总是只有一个元素。

@toops1 = $toops;

应该是

@toops1 = @$toops;

但为什么不直接使用@$toops而不是复制所有元素？

sub filter_random_4_toops_by_sum {
   my ($toops, $thresh) = @_;
   my @sorted_toops = map { [ $_, sum(@$_) ] } @$toops;
   my @filtered_toops = grep { $_[1] > $thresh } @sorted_toops;
   my @sortedReturn = map { $_->[0] } @filtered_toops;
   return \@sortedReturn;
}

甚至

sub filter_random_4_toops_by_sum {
   my ($toops, $thresh) = @_;
   return [
      map { $_->[0] }
         grep { $_[1] > $thresh }
            map { [ $_, sum(@$_) ] }
               @$toops
   ];
}

甚至

sub filter_random_4_toops_by_sum {
   my ($toops, $thresh) = @_;
   return [ grep { sum(@$_) > $thresh } @$toops ];
}

根据＆＃34; Tuple＆＃34;

1 个答案: