不懂字符串匹配

Question

尝试匹配字符串，其中一个与

匹配

有人可以为我解释这种行为吗？使用stringr函数时，未检测到匹配，但在使用==进行检查时，它是？

str_detect(str_sub(bit1, 1485, 1739), snips[10])
# [1] FALSE

str_sub(bit1, 1485, 1739) == snips[10]    
# [1] TRUE

当我查看str_sub(bit1, 1485, 1739)和snips[10]时，它们看起来完全相同，实际上来自相同的原始素材。

以下是实际的文本块：

    str_detect("HANOI - China has shut trade ports to Vietnamese vessels as the bird flu crisis deepens, the Xinhua News Agency reported. Some 40 ports along a 740-mile (791 kilometers) border with Vietnam have been closed in the southern Chinese province of Yunnan, stat", "HANOI - China has shut trade ports to Vietnamese vessels as the bird flu crisis deepens, the Xinhua News Agency reported. Some 40 ports along a 740-mile (791 kilometers) border with Vietnam have been closed in the southern Chinese province of Yunnan, stat")
    [1] FALSE

甚至是这个结果？

    str_detect(str1, str1)
    [1] FALSE