Source code for matchms.filtering.reduce_to_number_of_peaks

import logging
from math import ceil
from typing import Optional
import numpy
from ..Fragments import Fragments
from ..typing import SpectrumType

logger = logging.getLogger("matchms")

[docs]def reduce_to_number_of_peaks(spectrum_in: SpectrumType, n_required: int = 1, n_max: int = numpy.inf, ratio_desired: Optional[float] = None) -> SpectrumType: """Lowest intensity peaks will be removed when it has more peaks than desired. Parameters ---------- spectrum_in Input spectrum. n_required: Number of minimum required peaks. Spectra with fewer peaks will be set to 'None'. Default is 1. n_max: Maximum number of peaks. Remove peaks if more peaks are found. Default is inf. ratio_desired: Set desired ratio between maximum number of peaks and parent mass. For spectra without parent mass (e.g. GCMS spectra) this will raise an error when ratio_desired is used. Default is None. """ def _set_maximum_number_of_peaks_to_keep(): parent_mass = spectrum.get("parent_mass", None) if parent_mass and ratio_desired: n_desired_by_mass = int(ceil(ratio_desired * parent_mass)) return min(max(n_required, n_desired_by_mass), n_max) if not ratio_desired: return n_max raise ValueError("Cannot use ratio_desired for spectrum without parent_mass.") def _remove_lowest_intensity_peaks(): mz, intensities =, spectrum.peaks.intensities idx = intensities.argsort()[-threshold:] idx_sort_by_mz = mz[idx].argsort() spectrum.peaks = Fragments(mz=mz[idx][idx_sort_by_mz], intensities=intensities[idx][idx_sort_by_mz]) if spectrum_in is None: return None spectrum = spectrum_in.clone() if spectrum.peaks.intensities.size < n_required:"Spectrum with %s (<%s) peaks was set to None.", str(spectrum.peaks.intensities.size), str(n_required)) return None threshold = _set_maximum_number_of_peaks_to_keep() if spectrum.peaks.intensities.size < threshold: return spectrum _remove_lowest_intensity_peaks() return spectrum