python 中的pandas.DataFrame.fillna

DataFrame. fillna ( value=None,  method=None,  axis=None,  inplace=False,  limit=None,  downcast=None,  **kwargs ) [source]

Fill NA/NaN values using the specified method

Parameters:

value : scalar, dict, Series, or DataFrame Value to use to fill holes (e.g. 0), alternately a dict/Series/DataFrame of values specifying which value to use for each index (for a Series) or column (for a DataFrame). (values not in the dict/Series/DataFrame will not be filled). This value cannot be a list. method : {‘backfill’, ‘bfill’, ‘pad’, ‘ffill’, None}, default None Method to use for filling holes in reindexed Series pad / ffill: propagate last valid observation forward to next valid backfill / bfill: use NEXT valid observation to fill gap axis : {0 or ‘index’, 1 or ‘columns’} inplace : boolean, default False If True, fill in place. Note: this will modify any other views on this object, (e.g. a no-copy slice for a column in a DataFrame). limit : int, default None If method is specified, this is the maximum number of consecutive NaN values to forward/backward fill. In other words, if there is a gap with more than this number of consecutive NaNs, it will only be partially filled. If method is not specified, this is the maximum number of entries along the entire axis where NaNs will be filled. downcast : dict, default is None a dict of item->dtype of what to downcast if possible, or the string ‘infer’ which will try to downcast to an appropriate equal type (e.g. float64 to int64 if possible) 来源： http://pandas.pydata.org/pandas-docs/stable/generated/pandas.DataFrame.fillna.html