def find_snapshots(network, carrier, maximum = True, minimum = True, n = 3):
    
    """
    Function that returns snapshots with maximum and/or minimum feed-in of 
    selected carrier.

    Parameters
    ----------
    network : :class:`pypsa.Network
        Overall container of PyPSA
    carrier: str
        Selected carrier of generators
    maximum: bool
        Choose if timestep of maximal feed-in is returned.
    minimum: bool
        Choose if timestep of minimal feed-in is returned.
    n: int
        Number of maximal/minimal snapshots

    Returns
    -------
    calc_snapshots : 'pandas.core.indexes.datetimes.DatetimeIndex'
        List containing snapshots
    """
    
    if carrier == 'residual load':
        power_plants = network.generators[network.generators.carrier.
                                    isin(['solar', 'wind', 'wind_onshore'])]
        power_plants_t = network.generators.p_nom[power_plants.index] * \
                        network.generators_t.p_max_pu[power_plants.index]
        load = network.loads_t.p_set.sum(axis=1)
        all_renew = power_plants_t.sum(axis=1)
        all_carrier = load - all_renew

    if carrier in ('solar', 'wind', 'wind_onshore', 
                   'wind_offshore', 'run_of_river'):
        power_plants = network.generators[network.generators.carrier
                                          == carrier]

        power_plants_t = network.generators.p_nom[power_plants.index] * \
                        network.generators_t.p_max_pu[power_plants.index]
        all_carrier = power_plants_t.sum(axis=1)

    if maximum and not minimum:
       times = all_carrier.sort_values().head(n=n)

    if minimum and not maximum:
       times = all_carrier.sort_values().tail(n=n)

    if maximum and minimum:
        times = all_carrier.sort_values().head(n=n)
        times = times.append(all_carrier.sort_values().tail(n=n))

    calc_snapshots = all_carrier.index[all_carrier.index.isin(times.index)]

    return calc_snapshots
Function that returns snapshots with maximum and/or minimum feed-in of 
    selected carrier.

    Parameters
    ----------
    network : :class:`pypsa.Network
        Overall container of PyPSA
    carrier: str
        Selected carrier of generators
    maximum: bool
        Choose if timestep of maximal feed-in is returned.
    minimum: bool
        Choose if timestep of minimal feed-in is returned.
    n: int
        Number of maximal/minimal snapshots

    Returns
    -------
    calc_snapshots : 'pandas.core.indexes.datetimes.DatetimeIndex'
        List containing snapshots