Pandas DataFrame用最新的先前正值替换负值

import pandas as pd

# 创建示例 DataFrame
data = {
    'A': [1, -2, 3, -4, 5],
    'B': [6, -7, 8, -9, 10]
}
df = pd.DataFrame(data)

# 打印原始 DataFrame
print("原始 DataFrame:")
print(df)

# 定义函数来替换负值
def replace_negatives_with_previous_positive(series):
    result = series.copy()
    for i in range(len(series)):
        if series[i] < 0:
            for j in range(i-1, -1, -1):
                if series[j] > 0:
                    result[i] = series[j]
                    break
    return result

# 应用函数到每一列
for column in df.columns:
    df[column] = replace_negatives_with_previous_positive(df[column])

# 打印处理后的 DataFrame
print("处理后的 DataFrame:")
print(df)

原始 DataFrame:
   A  B
0  1  6
1 -2 -7
2  3  8
3 -4 -9
4  5 10
处理后的 DataFrame:
   A    B
0  1  6.0
1  1  6.0
2  3  8.0
3  3  8.0
4  5  10.0