Objective-C：如何在数组中找到最常见的字符串？

Question

我有一个来自在线数据库的字符串数组，我试图确定最常用的单词。数组中的值会有所不同，但我想检查我正在使用的任何集合或单词中最常见的单词。如果理论上我有以下数组...

NSArray *stringArray = [NSArray arrayWithObjects:@"Duck", @"Duck", @"Duck", @"Duck", @"Goose"];

我如何遍历这个数组来确定最常见的字符串，这显然是“Duck”？

Answer 1

您可以将单词用作字典的键。

NSMutableDictionary *words = [NSMutableDictionary dictionary];
for (NSString *word in stringArray) {
    if (!words[word]) {
        [words setValue:[NSDecimalNumber zero] forKey:word];
    }

    words[word] = [words[word] decimalNumberByAdding:[NSDecimalNumber one]];
}

现在遍历words 并找到具有最高值的键。

NSString *mostCommon;
NSDecimalNumber *curMax = [NSDecimalNumber zero];
for (NSString *key in [words allKeys]) {
    if ([words[key] compare:curMax] == NSOrderedDescending) {
        mostCommon = key;
        curMax = word[key];
    }
}

NSLog(@"Most Common Word: %@", mostCommon);

---

编辑：我认为我们可以做得更好，并在一个循环中完成所有操作，而不是遍历数组一次然后单独循环遍历排序字典。

NSString *mostCommon;
NSDecimalNumber *curMax = [NSDecimalNumber zero];
NSMutableDictionary *words = [NSMutableDictionary dictionary];
for (NSString *word in stringArray) {
    if (!words[word]) {
        [words setValue:[NSDecimalNumber zero] forKey:word];
    }

    words[word] = [words[word] decimalNumberByAdding:[NSDecimalNumber one]];

    if ([words[word] compare:curMax] == NSOrderedDescending) {
        mostCommon = word;
        curMax = words[word];
    }
}

NSLog(@"Most Common Word: %@", mostCommon);

这应该比我的答案预编辑快得多，尽管我不知道它与使用 NSCountedSet 答案相比如何。

Answer 2

最简单的方法大概是NSCountedSet:

NSCountedSet* stringSet = [[NSCountedSet alloc] initWithArray:strings];
NSString* mostCommon = nil;
NSUInteger highestCount = 0;

for(NSString* string in stringSet) {
    NSUInteger count = [stringSet countForObject:string];
    if(count > highestCount) {
        highestCount = count;
        mostCommon = string;
    }
}

Answer 3

尝试使用 NSPredicate。

NSUInteger count=0;
NSString *mostCommonStr;
for(NSString *strValue in stringArray) {
   NSUInteger countStr=[[stringArray filteredArrayUsingPredicate:[NSPredicate predicateWithFormat:@"self MATCHES[CD] %@, strValue]]count];
   if(countStr > count) {
       count=countStr;
       mostCommonStr=strValue;
   }
}
NSLog(@"The most commonstr is %@",mostCommonStr);