C++ algorithm like python's 'groupby'

Question

Are there any C++ transformations which are similar to itertools.groupby()?

Of course I could easily write my own, but I\'d prefer to leverage the idiomatic behavior

Answer 1

I wrote a C++ library to address this problem in an elegant way. Given your struct

struct foo
{
    int x;
    std::string y;
    float z;
};

To group by y you simply do:

std::vector dataframe;
...
auto groups = group_by(dataframe, &foo::y);

You can also group by more than one variable:

auto groups = group_by(dataframe, &foo::y, &foo::x);

And then iterate through the groups normally:

for(auto& [key, group]: groups)
{
    // do something
}

It also has other operations such as: subset, concat, and others.