pandas 熊猫四舍五入到最近的“n”
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Pandas round to the nearest "n"
提问by maxymoo
Numeric series have a nice rounding method for rounding to powers of ten, eg
数字系列有一个很好的四舍五入方法来四舍五入到十的幂，例如
>>> pd.Series([11,16,21]).round(-1)
0 10
1 20
2 20
dtype: int64
Is there an equivalently nice syntax for rounding to the nearest 5 (or other non-power of 10)? I'm sort of wishing that roundcould take non-integer values?
是否有同样好的语法可以四舍五入到最接近的 5（或其他非 10 的幂）？我有点希望round可以采用非整数值？
回答by Andy
You can utilize a custom rounding function and applyit to your series.
您可以使用自定义舍入函数并将apply其用于您的系列。
import pandas as pd
def custom_round(x, base=5):
return int(base * round(float(x)/base))
df = pd.Series([11,16,21]).apply(lambda x: custom_round(x, base=5))
Now you just need to adjust the baseto get to the nearest value you want.
现在您只需要调整base以获得您想要的最接近的值。
A couple examples:
几个例子：
Base = 5:
基数 = 5：
0 10
1 15
2 20
dtype: int64
Base = 7
基数 = 7
0 14
1 14
2 21
dtype: int64
Base = 3
基数 = 3
0 12
1 15
2 21
dtype: int64
Your goal of non-integer values can be done too.
您也可以实现非整数值的目标。
def custom_round(x, base=5):
return base * round(float(x)/base)
df = pd.Series([11.35,16.91,21.12]).apply(lambda x: custom_round(x, base=.05))
By rounding to the nearest 0.05, you'll get these results (notice I modified your series slightly for this example):
通过四舍五入到最接近的 0.05，您将得到以下结果（注意我在此示例中稍微修改了您的系列）：
0 11.35
1 16.90
2 21.10
dtype: float64
If you keep your original series of integers, this applywill change your series into floatvalues:
如果您保留原始整数系列，这apply会将您的系列更改为float值：
回答by maxymoo
I guess I could do this:
我想我可以这样做：
def round_down_to_nearest(self, n):
return (self // n) * n
pd.Series.round_down_to_nearest = round_down_to_nearest
