import numpy as np


def haversine_np(lon1, lat1, lon2, lat2):
    """
    Calculate the great circle distance between two points
    on the earth (specified in decimal degrees)

    (lon1, lat1) must be broadcastable with (lon2, lat2).

    """
    lon1, lat1, lon2, lat2 = map(np.radians, [lon1, lat1, lon2, lat2])

    dlon = lon2 - lon1
    dlat = lat2 - lat1

    a = np.sin(dlat/2.0)**2 + np.cos(lat1) * np.cos(lat2) * np.sin(dlon/2.0)**2

    c = 2 * np.arcsin(np.sqrt(a))
    km = 6367 * c
    return km


def bin_data_by(a, b, bin_ranges):
    nbins = len(bin_ranges)
    binned_data = []

    for i in range(nbins):
        rng = bin_ranges[i]
        idxs = (b >= rng[0]) & (b < rng[1])
        binned_data.append(a[idxs])

    return binned_data


def get_bin_ranges(lop, hip, bin_size=100):
    bin_ranges = []
    delp = hip - lop
    nbins = int(delp/bin_size)

    for i in range(nbins):
        rng = [lop + i*bin_size, lop + i*bin_size + bin_size]
        bin_ranges.append(rng)

    return bin_ranges


# t must be monotonic increasing
def get_breaks(t, threshold):
    t_0 = t[0:t.shape[0]-1]
    t_1 = t[1:t.shape[0]]
    d = t_1 - t_0
    idxs = np.nonzero(d > threshold)
    return idxs