Calculation of "classical" Fundamental Diagram

With the current functions of PedPy it is not easy to create the classical form of a FD.

I planned to create the density-flow diagramm for simple unidirectional corridor data and started with the calculation of classical density with compute_classic_density() which was pretty straight forward. (side note: the result is not a pd.dataframe as written in the API but the 'frame' column is defined as index)

The flow was more complicated... I used the calculation of the N-t-diagramm with compute_n_t() and tried to caluculate the flow from this using compute_flow(). Here comes question/ problem number one: why is it mandatory to insert the "individual_speed" for a flow calculation? This is not directly needed for flow calculation.

Anyway: after calculating a speed as well, I managed to run compute_flow() and got a dataframe with two columns: flow and mean_speed.
So now I have the classical density as pd.dataframe with frame and density as columns; and a dataframe with flow and mean_speed... This does not really get me closer to a classical Fundamental Diagram as I would somehow need to match the entries for density and flow. But I think no fuction to perform this currently exists in PedPy.

Is there any way to directly calculate a classical fundamental diagramm using PedPy? The user guide says: "Basic measures as velocity, flow, and density can directly be computed and then combined to obtain fundamental diagrams." But I somehow fail to achieve this 😅