python pandas left join function

gistfile1.py

def left_join(df1, df2, key, cols, lsuffix="", rsuffix="", default_value=None):
    if type(key) != list:
        key_left, key_right = key, key
    else:
        key_left, key_right = key[0], key[1]
        
    if type(cols) != list:
        cols = [cols,]
    
    ind = pd.match(df1[key], df2[key])
    ind_left = np.where(ind>=0)[0]
    ind_right = ind[ind>=0]
    for col in cols:
        alias = lsuffix + col + rsuffix
        df1[alias] = default_value
        df1[alias][ind_left] = df2.ix[ind_right,col]
    return df1