mdf.py 文件源码

def select(self, channels, dataframe=False):
        """ return the channels listed in *channels* argument

        Parameters
        ----------
        channels : list
            list of channel names to be filtered
        dataframe: bool
            return a pandas DataFrame instead of a list of Signals; in this
            case the signals will be interpolated using the union of all
            timestamps

        Returns
        -------
        signals : list
            lsit of *Signal* objects based on the input channel list

        """

        # group channels by group index
        gps = {}
        for ch in channels:
            if ch in self.channels_db:
                for group, index in self.channels_db[ch]:
                    if group not in gps:
                        gps[group] = []
                    gps[group].append(index)
            else:
                message = ('MDF filter error: '
                           'Channel "{}" not found, it will be ignored')
                warn(message.format(ch))
                continue

        # append filtered channels to new MDF
        signals = {}
        for group in gps:
            grp = self.groups[group]
            data = self._load_group_data(grp)
            for index in gps[group]:
                signal = self.get(group=group, index=index, data=data)
                signals[signal.name] = signal

        signals = [signals[channel] for channel in channels]

        if dataframe:
            times = [s.timestamps for s in signals]
            t = reduce(np.union1d, times).flatten().astype(np.float64)
            signals = [s.interp(t) for s in signals]
            times = None

            pandas_dict = {'t': t}
            for sig in signals:
                pandas_dict[sig.name] = sig.samples

            signals = DataFrame.from_dict(pandas_dict)

        return signals