在 Python 中乘以 dataframe 中的数组

Question

I am reading a specific column from a csv file. I want to multiply the elements of this array with 2 . When I do so, the array size is doubling instead of multiplying each element with 2 . I have shared the CSV file. I also present the current and expected outputs.

import pandas as pd
data = pd.read_csv("Data.csv")

B = pd.read_csv("Data.csv", sep=',', usecols=['sigma'], squeeze=True)
print("B[0] =",B[0]*2)

The CSV file looks like

enter image description here

The current output is

B[0] = [array([[0.02109],
       [0.02109],
       [array([[0.02109],
       [0.02109]])]

The expected output is

B[0] = [array([[.04218],
       [.04218]])]

Answer 1

Does this help?

df = pd.DataFrame({
    "col" : [[0.2, 0.3],[0.3, 0.4],[0.4, 0.5],[0.5, 0.6]]
})

Multiply it by 2

df.col = df.col.apply(lambda x: [num * 2 for num in x])

Result

    col
0   [0.4, 0.6]
1   [0.6, 0.8]
2   [0.8, 1.0]
3   [1.0, 1.2]