更改 python 代码以摆脱 exec() 和 eval()

Question

I am new to python and am trying to improve a code's readability as well as speed by removing the recurrent use of exec() and eval(). However it is not obvious to me how I need to alter to code to obtain this.

I want the program to make dataframes and arrays with names based on input. Let's say that the input is like this:

A=[Red, Blue]
B=[Banana, Apple]
C=[Pie, Cake]

Then the code will then make a dataframe with a name based on each combination of input: Red_Banana_Pie, Red_Banana_Cake, Red_Apple_Pie, Red_Apple_Cake, etc. by looping through the three lists.

for color in A[0:len(A)]: 
    for fruit in B[0:len(B)]: 
        for type in C[0:len(C)]: 

And then in each loop:

exec('DataFr_'+color+'_'+fruit+'_'+type+'=pd.DataFrame((Data),columns=[\'Title1\',\'Title2\'])')

How can I do this without the exec command?

Answer 1

When you run exec('DataFr_'+color+'_'+fruit+'_'+type+'=pd.DataFrame((Data),columns=[\'Title1\',\'Title2\'])') , you will get 8 DataFrames that has different names. But I don't recommend this because you have to use eval() every time you want to access to your DataFrame.(otherwise you can hardcode that, but that's really bad thing)

I think you need multi-dimensional dictionary for dataframe.

When the input is

A=["Red", "Blue"]
B=["Banana", "Apple"]
C=["Pie", "Cake"]

[+] additionally, you'll basically get user input as string in python.(like "hello, world!" )

data_set = {}
for color in A:
    data_set.update({color:{}})
    for fruit in B: 
        data_set[color].update({fruit:{}})
        for type in C:
            data_set[color][fruit].update({type:pd.DataFrame((Data),columns=['Title1','Title2'])})
                                                     # I think you have some Data in other place, right?

[+] moreover, you can iterate List without [0:len(A)] in python.

Then you can use each DataFrame by data_set['Red']['Banana']['Cake'] .(your implementation will be data_set[A[0]][B[0]][C[1]] ) Then you can dynamically create DataFrame for each color, fruit, type without eval, and access to them without hardcoded value.