Arrays 计算两个数组元素在一起出现的次数
我有一大堆词。 我想数一数,两个特定的单词出现的次数少于给定的距离Arrays 计算两个数组元素在一起出现的次数,arrays,perl,Arrays,Perl,我有一大堆词。 我想数一数,两个特定的单词出现的次数少于给定的距离 例如,如果“time”和“late”之间的距离不超过三个单词,那么我想增加一个计数器。单词“time”和“late”可以在数组中出现数百次。我怎样才能找到它们彼此靠近的时间数呢?你没有问任何问题,所以我想你已经想出了一个算法 遍历索引。 如果在该索引中找到第一个单词, 请注意索引 如果在该索引中找到第二个单词, 请注意索引 从另一个索引中减去一个索引 注: 您可能需要添加检查以确保找到每个单词 您没有指定当其中一个单词出
例如,如果“time”和“late”之间的距离不超过三个单词,那么我想增加一个计数器。单词“time”和“late”可以在数组中出现数百次。我怎样才能找到它们彼此靠近的时间数呢?你没有问任何问题,所以我想你已经想出了一个算法
- 您可能需要添加检查以确保找到每个单词
- 您没有指定当其中一个单词出现多次时应该发生什么
关于评论中提出的问题:
- 假设您只关心第二个单词和第一个单词的前一个实例之间的距离
my @words = qw( word1 word2 word3 word4 word5 word6 );
# That can be expensive, but you do it only once
my %index;
@index{@words} = (0..$#words);
# That will be real quick
my $distance = $index{"word6"} - $index{"word2"}
print "Distance: $distance \n";
上述脚本的输出将是:
Distance: 4
注意:创建索引哈希可能会很昂贵。但是,如果您计划进行许多距离检查,这可能是值得的,因为任何查找都很快(恒定时间,而不是事件日志(n)) 是否需要支持重复的单词
#! /usr/bin/perl
use strict;
use warnings;
use constant DEBUG => 0;
my @words;
if( $ARGV[0] && -f $ARGV[0] ) {
open my $fh, "<", $ARGV[0] or die "Could not read $ARGV[0], because: $!\n";
my $hughTestFile = do { local $/; <$fh> };
@words = split /[\s\n]/, $hughTestFile; # $#words == 10M words with my test.log
# Test words (below) were manually placed at equal distances (~every 900K words) in test.log
# With above, TESTS ran in avg of 15 seconds. Likely test.log was in buffers/cache.
} else {
@words = qw( word1 word2 word3 word4 word5 word6 word7 word8 word4 word9 word0 );
}
sub IndexOf {
my $searchFor = shift;
return undef if( !$searchFor );
my $Nth = shift || 1;
my $length = $#words;
my $cntr = 0;
for my $word (@words) {
if( $word eq $searchFor ) {
$Nth--;
return $cntr if( $Nth == 0 );
}
$cntr++;
}
return undef;
}
sub Distance {
# args: <1st word>, <2nd word>, [occurrence_of_1st_word], [occurrence_of_2nd_word]
# for occurrence counts: 0, 1 & undef - all have the same effect (1st occurrence)
my( $w1, $w2 ) = ($_[0], $_[1]);
my( $n1, $n2 ) = ($_[2] || undef, $_[3] || undef );
die "Missing words\n" if( !$w1 );
$w2 = $w1 if( !$w2 );
my( $i1, $i2 ) = ( IndexOf($w1, $n1), IndexOf($w2, $n2) );
if( defined($i1) && defined($i2) ) {
my $offset = $i1-$i2;
print " Distance (offset) = $offset\n";
return undef;
} elsif( !defined($i1) && !defined($i2) ) {
print " Neither words were ";
} elsif( !defined($i1) ) {
print " First word was not ";
} else {
print " Second word was not ";
}
print "found in list\n";
return undef;
}
# TESTS
print "Your array has ".$#words." words\n";
print "When 1st word is AFTER 2nd word:\n";
Distance( "word7", "word3" );
print "When 1st word is BEFORE 2nd word:\n";
Distance( "word2", "word5" );
print "When 1st word == 2nd word:\n";
Distance( "word4", "word4" );
print "When 1st word doesn't exist:\n";
Distance( "word00", "word6" );
print "When 2nd word doesn't exist:\n";
Distance( "word1", "word99" );
print "When neither 1st or 2nd words exist:\n";
Distance( "word00", "word99" );
print "When the 1st word is AFTER the 2nd OCCURRENCE of 2nd word:\n";
Distance( "word9", "word4", 0, 2 );
print "When the 1st word is BEFORE the 2nd OCCURRENCE of the 2nd word:\n";
Distance( "word7", "word4", 1, 2 );
print "When the 2nd OCCURRENCE of the 2nd word doesn't exist:\n";
Distance( "word7", "word99", 0, 2 );
print "When the 2nd OCCURRENCE of the 1st word is AFTER the 2nd word:\n";
Distance( "word4", "word2", 2, 0 );
print "When the 2nd OCCURRENCE of the 1st word is BEFORE the 2nd word:\n";
Distance( "word4", "word0", 2, 0 );
print "When the 2nd OCCURRENCE of the 1st word exists, but 2nd doesn't:\n";
Distance( "word4", "word99", 2, 0 );
print "When neither of the 2nd OCCURRENCES of the words exist:\n";
Distance( "word00", "word99", 2, 2 );
print "Distance between 2nd and 1st OCCURRENCES of the same word:\n";
Distance( "word4", "", 2, 1 );
#/usr/bin/perl
严格使用;
使用警告;
使用常量DEBUG=>0;
我的文字;
如果($ARGV[0]&&f$ARGV[0]){
打开我的$fh,"问题可能重复,以匹配下面评论中提出的问题。缺点:即使你想要的两个单词是前两个单词,你也必须处理整个列表。这是真的。另一方面,一旦创建了索引哈希,它可以用于快速查找。因此这是一种折衷。我会在回答中注意到这一点。如果你t保留必要数量的散列存储桶这可能是O(n logn),因此将混响添加到answInserting n元素到散列中是O(n),因此是O(n)无需预先保留。@ikegami是的,以防重新刷新。OP表示数组很大,因此将进行重新刷新。此外,如果数组已排序,则可以使用B搜索太快来完成此操作。如果“时间”和“延迟”之间的距离