如何使用变量选择dataframe中的列

import pandas as pd

# 创建一个示例DataFrame
data = {
    'A': [1, 2, 3],
    'B': [4, 5, 6],
    'C': [7, 8, 9]
}
df = pd.DataFrame(data)

# 静态选择列
selected_column_static = df['A']
print("静态选择列:")
print(selected_column_static)

# 动态选择列
column_name = 'B'
selected_column_dynamic = df[column_name]
print("\n动态选择列:")
print(selected_column_dynamic)

# 使用变量选择多列
columns_to_select = ['A', 'C']
selected_columns = df[columns_to_select]
print("\n选择多列:")
print(selected_columns)

if column_name in df.columns:
    selected_column = df[column_name]
else:
    print(f"列名 {column_name} 不存在")

column_name = 'Column Name'
selected_column = df[column_name]

column_name = str('B')  # 确保变量是字符串类型
selected_column = df[column_name]