def _upsample(self, method, limit=None, fill_value=None):
self._set_binner()<EOL>if self.axis:<EOL><INDENT>raise AssertionError('<STR_LIT>')<EOL><DEDENT>if self._from_selection:<EOL><INDENT>raise ValueError("<STR_LIT>"<EOL>"<STR_LIT>"<EOL>"<STR_LIT>"<EOL>"<STR_LIT>")<EOL><DEDENT>ax = self.ax<EOL>obj = self._selected_obj<EOL>binner = self.binner<EOL>res_index = self._adjust_binner_for_upsample(binner)<EOL>if limit is None and to_offset(ax.inferred_freq) == self.freq:<EOL><INDENT>result = obj.copy()<EOL>result.index = res_index<EOL><DEDENT>else:<EOL><INDENT>result = obj.reindex(res_index, method=method,<EOL>limit=limit, fill_value=fill_value)<EOL><DEDENT>result = self._apply_loffset(result)<EOL>return self._wrap_result(result)<EOL>
Parameters
----------
method : string {'backfill', 'bfill', 'pad',
    'ffill', 'asfreq'} method for upsampling
limit : int, default None
    Maximum size gap to fill when reindexing
fill_value : scalar, default None
    Value to use for missing values

See Also
--------
.fillna