我有一个关于 Python 字母的数值计算的问题

Question

df = pd.DataFrame({'num':['9','','3','7','11']})
col_nm = 'num'
print(df)

  num
0   9
1    
2   3
3   7
4  11

If the num is greater than 5, I will convert it to 5. But after the number 10, there is no conversion.

string ="np.where(num == '',num,np.where(num >= '5', '5', num))"
string = string.replace(col_nm,"df['"+col_nm+"']")
df[col_nm] = eval(string)
print(df)

  num
0   5
1    
2   3
3   5
4  11

Is there any way to solve the logics using data and string while keeping them intact?

Answer 1

We need first convert to_numeric then use condition assign

df['num'] = pd.to_numeric(df['num'],errors='coerce')
df.loc[df['num'].between(5,10),'num'] = 5
df
Out[97]: 
    num
0   5.0
1   NaN
2   3.0
3   5.0
4  11.0