pandas 熊猫用新值更新数据框行

pandas update dataframe row with new value

提问by jake wong

I have a text file which has been read into pandas by df1 = pandas.read_csv(r'fruits.txt', sep=',')

我有一个文本文件，它已被读入Pandas df1 = pandas.read_csv(r'fruits.txt', sep=',')

    item  freshness
0   apple    2.2
1   pear     0.0

and a series of calculations that would yield the result of apple = 2.3

和一系列的计算，将产生的结果 apple = 2.3

Is it possible to do a pandas.updateso that I can update the value of freshnessfor applein the dataframe to 2.3?

是否可以执行 apandas.update以便我可以将数据框中的freshnessfor值更新apple为2.3？

回答by jezrael

IIUC you need loc:

IIUC你需要loc：

apple = 2.3

print df['item'] == 'apple'
0     True
1    False
Name: item, dtype: bool

df.loc[df['item'] == 'apple', 'freshness'] = apple
print df
    item  freshness
0  apple        2.3
1   pear        0.0