def read_blob(self,blob_dim,n_blob=0):
        """Read blob from a selection.
        """

        n_blobs = self.calc_n_blobs(blob_dim)
        if n_blob > n_blobs or n_blob < 0:
            raise ValueError('Please provide correct n_blob value. Given %i, but max values is %i'%(n_blob,n_blobs))

        # This prevents issues when the last blob is smaller than the others in time.
        if blob_dim[self.time_axis]*(n_blob+1) > self.selection_shape[self.time_axis]:
            updated_blob_dim = (int(self.selection_shape[self.time_axis] - blob_dim[self.time_axis]*n_blob), 1, int(blob_dim[self.freq_axis]))
        else:
            updated_blob_dim = [int(i) for i in blob_dim]

        blob_start = self._find_blob_start()
        blob = np.zeros(updated_blob_dim, dtype=self._d_type)

        # EE: For now; also assuming one polarization and one beam.

        # Assuming the blob will loop over the whole frequency range.
        if self.f_start == self.f_begin and self.f_stop == self.f_end:

            blob_flat_size = np.prod(blob_dim)
            updated_blob_flat_size = np.prod(updated_blob_dim)

            # Load binary data
            with open(self.filename, 'rb') as f:
                f.seek(int(self.idx_data + self._n_bytes  * (blob_start + n_blob*blob_flat_size)))
                dd = np.fromfile(f, count=updated_blob_flat_size, dtype=self._d_type)

            if dd.shape[0] == updated_blob_flat_size:
                blob = dd.reshape(updated_blob_dim)
            else:
                logger.info('DD shape != blob shape.')
                blob = dd.reshape((int(dd.shape[0]/blob_dim[self.freq_axis]),blob_dim[self.beam_axis],blob_dim[self.freq_axis]))
        else:

            for blobt in range(updated_blob_dim[self.time_axis]):

                #Load binary data
                with open(self.filename, 'rb') as f:
                    f.seek(int(self.idx_data + self._n_bytes * (blob_start + n_blob*blob_dim[self.time_axis]*self.n_channels_in_file + blobt*self.n_channels_in_file)))
                    dd = np.fromfile(f, count=blob_dim[self.freq_axis], dtype=self._d_type)

                blob[blobt] = dd

#         if self.header[b'foff'] < 0:
#             blob = blob[:,:,::-1]

        return blob
Read blob from a selection.