python - 用不等长度的列表填充 Pandas 列

Question

我在使用不等长度列表中的值填充 Pandas 数据帧时遇到问题。

nx_lists_into_df 是 numpy 数组的列表。

我收到以下错误:

ValueError: Length of values does not match length of index

代码如下:

# Column headers
df_cols = ["f1","f2"]

# Create one dataframe fror each sheet
df1 = pd.DataFrame(columns=df_cols)
df2 = pd.DataFrame(columns=df_cols)

# Create list of dataframes to iterate through
df_list = [df1, df2]

# Lists to be put into the dataframes   
nx_lists_into_df = [[array([0, 1, 3, 4, 7]),
                     array([2, 5, 6, 8])],
                    [array([0, 1, 2, 6, 7]),
                     array([3, 4, 5, 8])]]

# Loop through each sheet (i.e. each round of k folds)
for df, test_index_list in zip_longest(df_list, nx_lists_into_df):
    counter = -1
    # Loop through each column in that sheet (i.e. each fold)
    for col in df_cols:
        print(col)
        counter += 1
        # Add 1 to each index value to start indexing at 1
        df[col] = test_index_list[counter] + 1

感谢您的帮助。

编辑:结果应该是这样的:-

print(df1)

   f1   f2
0   0    2
1   1    5
2   3    6
3   4    8
4   7  NaN

print(df2)

   f1   f2
0   0    3
1   1    4
2   2    5
3   6    8
4   7  NaN

Answer 1

我们将利用 pd.Series 附加适当的索引，并允许我们使用 pd.DataFrame 构造函数，而不会提示长度不等。

df1, df2 = (
    pd.DataFrame(dict(zip(df_cols, map(pd.Series, d))))
    for d in nx_lists_into_df
)

<小时/>

print(df1)

   f1   f2
0   0  2.0
1   1  5.0
2   3  6.0
3   4  8.0
4   7  NaN

<小时/>

print(df2)

   f1   f2
0   0  3.0
1   1  4.0
2   2  5.0
3   6  8.0
4   7  NaN

<小时/>

设置

from numpy import array

nx_lists_into_df = [[array([0, 1, 3, 4, 7]),
                     array([2, 5, 6, 8])],
                    [array([0, 1, 2, 6, 7]),
                     array([3, 4, 5, 8])]]

# Column headers
df_cols = ["f1","f2"]