loop through variables names in Python

Question

I am working in Python. I have a dataframe called df with 3 columns: a, b, c. I want to do a loop which loops through all variables and generates a numpy array for each variable and cuts the last number of each variable. So far I have tried, but it is not working:

df = pd.DataFrame(
    [[1, 2, 3],
    [4, 5, 6],
    [7, 8, 9]],
    columns=['a', 'b', 'c'])
    variables= [a,b,c]
    for x in variables:
        x  = np.transpose(np.matrix(df.x.to_numpy(np.float64)))
        x=x[:-1]

Note that you are reassigning your loop variable `x`, which probably isn't what you want. — 0x5453, Jan 19 '21 at 20:56
I do want to generate 3 variables called a,b and c. This is probably not optimal but I have the rest of the code generated like this... — Alex, Jan 19 '21 at 20:57
`df.to_numpy()` produces a 2d array, `df.x` is series, and result is 1d. Why `np.matrix` and `transpose`? If you want to assign the the elements of some array to 3 variables use `unpacking`, `a,b,c = np.array([1,2,3])`. — hpaulj, Jan 19 '21 at 21:40

score 0 · Answer 1 · answered Jan 19 '21 at 21:11

From comments:

I do want to generate 3 variables called a,b and c. This is probably not optimal but I have the rest of the code generated like this

It sounds like what you're really asking here is how to dynamically set a variable name to match an arbitrary character string.

If you reeeeallly want to do that, this question and its chain of duplicates will give you some options.

But I would strongly STRONGLY encourage you to look for other ways of doing this. A dict is the most obvious option. If the rest of your code requires it, you're probably best off fixing up the rest of your code.

loop through variables names in Python

1 Answers1