Question

我正在尝试防止在功能data.frame上添加重复项，但尚未成功。你能帮我如何做到这一点吗？预先感谢。

	V1	V2	V3	V4	V5
1	0	0	0	0	0
2	0	0	223	13	9
3	0	223	0	57	28
4	0	13	57	0	82
5	0	9	28	82	0

程序的输出是；

example_data

Answer 1

如评论中所述，您仅检查重复的family_name，而不检查child_name。您可以使用std::find搜索std::vector

void add_child(map<string, vector<string>> &family, const string & family_name, const string & child_name)
{
    auto f_it = family.find(family_name);

    if (f_it != family.cend())
    {
        auto c_it = find(f_it->second.begin(), f_it->second.end(), child_name);
        if (c_it == f_it->second.end())
        {
            f_it->second.insert(c_it, child_name);
        }
        else
        {
            cerr << "Error: Already has child <" << child_name << ">" << endl;
        }
    }
    else
    {
        cerr << "Error: No family <" << family_name << 
                "> for child <" << child_name << ">" << std::endl;
    }
}

或者，您也可以使用std::map<std::string, std::set<std::string>>来确保唯一性。此外，您可以利用insert的返回值只查找每个名称一次。

void add_family(map<string, set<string>> &family, const string &name)
{
    if (!family.insert({name, {}}).second)
    {
        cerr << "Error: Already has family <" << name << ">" << endl;
    }
}

void add_child(map<string, set<string>> &family, const string & family_name, const string & child_name)
{
    auto it = family.find(family_name);

    if (it == family.cend())
    {
        cerr << "Error: No family <" << family_name << 
                "> for child <" << child_name << ">" << std::endl;
    } else if (!it->second.insert(child_name).second)
    {
        cerr << "Error: Already has child <" << child_name << ">" << endl;
    }
}

但我认为这种设计不雅致。我完全不会理会add_family。只需利用map和set的不变式即可。

void add_child(map<string, set<string>> &family, const string & family_name, const string & child_name)
{
    family[family_name].insert(child_name);
}

防止向量重复

1 个答案: