Python 列上的累计和和百分比？
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Cumulative sum and percentage on column?
提问by ComputerFellow
I have a DataFramelike this:
我有一个DataFrame这样的：
df:
df：
fruit val1 val2
0 orange 15 3
1 apple 10 13
2 mango 5 5
How do I get Pandas to give me a cumulative sum and percentage column on only val1?
我如何让 Pandas 只给我一个累积总和和百分比列val1？
Desired output:
期望的输出：
df_with_cumsum:
df_with_cumsum：
fruit val1 val2 cum_sum cum_perc
0 orange 15 3 15 50.00
1 apple 10 13 25 83.33
2 mango 5 5 30 100.00
I tried df.cumsum(), but it's giving me this error:
我试过了df.cumsum()，但它给了我这个错误：
TypeError: ufunc 'isnan' not supported for the input types, and the inputs could not be safely coerced to any supported types according to the casting rule ''safe''
类型错误：输入类型不支持 ufunc 'isnan'，并且无法根据转换规则 ''safe'' 将输入安全地强制转换为任何受支持的类型
采纳答案by BrenBarn
df['cum_sum'] = df['val1'].cumsum()
df['cum_perc'] = 100*df['cum_sum']/df['val1'].sum()
This will add the columns to df. If you want a copy, copy dffirst and then do these operations on the copy.
这会将列添加到df. 如果要副本，df请先复制，然后在副本上执行这些操作。
回答by Gene
It's a good answer, but written in 2014. I just modified a little bit, so it can pass the compiler and results looks similar to the example.
这是一个很好的答案，但写于 2014 年。我只是修改了一点，所以它可以通过编译器，结果看起来与示例类似。
df['cum_sum'] = df["val1"].cumsum()
df['cum_perc'] = round(100*df.cum_sum/df["val1"].sum(),2)
