在 Python 中重新定位数据框中的列

Question

我想知道是否有一种简单的方法可以使用 pandas 来重新定位数据框中的单个列，该方法可以模拟 dplyr 函数（在 R 中）“重新定位”。由于我通过几次搜索没有找到任何与此非常接近的内容，因此我和一位工作中的朋友创建了一个简单的函数来使用 python 执行此操作，我认为与可能需要它的每个人分享它会很好。

Answer 1

1. 功能

def relocate_column(df, relocated_col, reference_col,distance=1):
    # Relocates a column based on another column's position
    # df = dataframe in question
    # relocated_col = column that will be relocated
    # reference_col = column that will be used as reference
    # distance = how many columns from the reference will the relocated column be placed. 
    # Positive 'distance' is after, negative is before. +1 is immediately after, -1 is immediately before
    # List all columns in df
    df_columns = list(df.columns)
    # Check if both columns exist
    if reference_col not in df_columns:
        print(f'Column {reference_col} not found in dataframe')
        return df
    if relocated_col not in df_columns:
        print(f'Column {relocated_col} not found in dataframe')
        return df
    # Relocates the column based on inputed distance (default = 1)
    df_columns.remove(relocated_col)
    df_columns.insert(df_columns.index(reference_col) + distance, relocated_col)
    # Applies new order to dataframe
    df = df[df_columns]
    return df

2. DF 示例（来自 https://pandas.pydata.org/docs/reference/api/pandas.DataFrame.sample.html）：

df = pd.DataFrame({'num_legs': [2, 4, 8, 0],
                   'num_wings': [2, 0, 0, 0],
                   'num_specimen_seen': [10, 2, 1, 8]},
                  index=['falcon', 'dog', 'spider', 'fish'])
print(df)
        num_legs  num_wings  num_specimen_seen
falcon         2          2                 10
dog            4          0                  2
spider         8          0                  1
fish           0          0                  8

3. 搬迁：

df = relocate_column(df, 'num_wings', 'num_legs')
print(df)

        num_wings  num_legs  num_specimen_seen
falcon          2         2                 10
dog             0         4                  2
spider          0         8                  1
fish            0         0                  8

4. 总结：这个函数非常简单，它不适用于多列，只有一列，因为我只需要填充 dplyr 的重定位。