resample_ecg

from scipy.signal import decimate, resample_poly


def resample_ecg(trace, input_freq, output_freq, axis=-1):
    """Resample ecg.

    `trace` should be a multidimensional numpy array. `axis` gives which axis will be resampled (be default the last
    one). `input_freq` and `output_freq` are the input and output frequency (in heartz). Use the most appropriate SciPy
    function vailable: first try decimate (with bidirectional filtering), if the input and output frequencies are not
    multiple, it resamples using polyphase filtering.
    """
    trace = np.atleast_1d(trace).astype(float)
    if input_freq != int(input_freq):
        raise ValueError("input_freq must be an integer")
    if output_freq != int(output_freq):
        raise ValueError("output_freq must be an integer")

    if input_freq == output_freq:
        new_trace = trace
    elif np.mod(input_freq, output_freq) == 0:
        new_trace = decimate(trace, q=input_freq//output_freq,
                             ftype='iir', zero_phase=True, axis=axis)
    else:
        new_trace = resample_poly(trace, up=output_freq, down=input_freq, axis=axis)
    return new_trace