pyarrow 将列添加到 pyarrow 表

Question

我有一个形状为 6132,7 的 pyarrow 表名称 final_table 我想向该表添加列

 list_ = ['IT'] * 6132
 final_table.append_column('COUNTRY_ID', list_)

但我收到以下错误 ArrowInvalid：添加的列的长度必须与表的长度匹配。预期长度 6132 但得到长度 12264

Answer 1

根据文档：

Append column at end of columns.

Parameters
field (str or Field) – If a string is passed then the type is deduced from the column data.

column (Array, list of Array, or values coercible to arrays) – Column data.

Returns
pyarrow.Table – New table with the passed column added.

我认为 pyarrow 假设您提供的是list of Array. 为避免混淆，您应该传递一个箭头数组

col_a = pa.array([1, 2, 3], pa.int32())
col_b = pa.array(["X", "Y", "Z"], pa.string())

table = pa.Table.from_arrays(
    [col_a, col_b],
    schema=pa.schema([
        pa.field('a', col_a.type),
        pa.field('b', col_b.type),
    ])
)

table.append_column('COUNTRY_ID', pa.array(['IT'] * len(table), pa.string()))