Find the cluster `i` that is closest to the datapoint `e`.

def estimate_map(interface, state, label, inp):
    """Find the cluster `i` that is closest to the datapoint `e`."""
    out = interface.output(0)
    centers = {}
    for row in inp:
        row = row.strip().split(state["delimiter"])
        if len(row) > 1:
            x = [(0 if row[i] in state["missing_vals"] else float(row[i])) for i in state["X_indices"]]
            cluster = min((state['dist'](c, x), i) for i, c in state['centers'])[1]
            vertex = state['create'](x, 1.0)
            centers[cluster] = vertex if cluster not in centers else state["update"](centers[cluster], vertex)

    for cluster, values in centers.iteritems():
        out.add(cluster, values)