如何在pandas dataframe中为新列设置参数，或者为python上的值计数设置参数？

import pandas as pd

# 示例DataFrame
data = {'A': [1, 2, 3, 4],
        'B': [10, 20, 30, 40]}
df = pd.DataFrame(data)

# 创建新列'C'，其值为列'A'和列'B'的和
df['C'] = df['A'] + df['B']
print(df)

# 如果列'A'的值大于2，则新列'D'的值为'Large'，否则为'Small'
df['D'] = df['A'].apply(lambda x: 'Large' if x > 2 else 'Small')
print(df)

# 对列'A'的值进行计数
count = df['A'].value_counts()
print(count)

# 获取DataFrame的行数和列数
rows, cols = df.shape
print(f"Rows: {rows}, Columns: {cols}")

import pandas as pd

# 创建一个示例DataFrame
df = pd.DataFrame({
    'Numbers': [1, 2, 3, 4, 5],
    'Letters': ['a', 'b', 'c', 'd', 'e']
})

# 添加一个新列，该列的值是'Numbers'列的两倍
df['Doubled'] = df['Numbers'] * 2

# 添加一个新列，根据'Numbers'列的值是奇数还是偶数
df['Parity'] = df['Numbers'].apply(lambda x: 'Even' if x % 2 == 0 else 'Odd')

print(df)

   Numbers Letters  Doubled Parity
0        1       a        2    Odd
1        2       b        4   Even
2        3       c        6    Odd
3        4       d        8   Even
4        5       e       10    Odd