def train_test_split(data, target, train_ind, test_ind):
    """
    Splits ML input and targets into training and test sets
    from the specified indices
    
    Parameters
    ----------
        data :
            npy array of the input time series
        target :
            npy array of ML targets
        train_ind :
            list of training indices
        test_ind :
            list of test indicies
    Returns
    ----------
        train :
            npy array of time series training set
        test  :
            npy array of time series test set
        train_target :
            npy array of training targets
        test_target :
            npy array of test targets
    """
    train = data[train_ind,:]
    train_target = target[train_ind]
    test = data[test_ind,:]
    test_target = target[test_ind]
    return train, test, train_target, test_target