使用 pandas 计算列中的数学运算 [英] To calculate maths operation in a column using pandas

问题描述

我想使用python来获取CSV文件列中数学运算的最终值，我是否可以获取如下所示的值?

I would like to use python to get final values for maths operation in a column of a CSV file, may I know is it possible to get the value as below?

原始CSV:

Type Total
A    2+2
B    (10/2)*5
C    5-2*3

预期输出:

Type Total
A    4
B    25
C    -1

我已经尝试过搜索，但是对此一无所知...所有数据都是字符串形式，我试图转换为浮点数，但是由于数学运算，所以无法完成.

I have tried searching around but I could not get any idea on it... All data are in string, I tried to convert to float but due to the maths operation, so it cannot be done.

推荐答案

使用 pandas.eval 和不使用:

df['Total'] = pd.eval(df['Total'])

因为失败了，甚至超过了100行.

because failed if more like 100 rows.

如果只需要处理不丢失的值:

If need working only for not missing values:

mask = df['Total'].notna()
df.loc[mask, 'Total'] = df.loc[mask, 'Total'].apply(pd.eval)

如果可能，某些无法处理的值将使用自定义函数和 try-except :

If possible some values which cannot be processed use custom function with try-except:

print (df)
  Type     Total
0    A       2+2
1    B  (10/2)*5
2    C     5-2*3
3    D       NaN
4    E       aaa

def func(x):
    try:
        return pd.eval(x)
    except:
        return x

df['Total'] = df['Total'].apply(func)
print (df)
  Type Total
0    A     4
1    B    25
2    C    -1
3    D   NaN
4    E   aaa

这篇关于使用 pandas 计算列中的数学运算的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！