pyarrow将列添加到pyarrow表

Question

我有一个形状为6132,7的pyarrow表名为final_table，7我想向该表中添加列

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

但我得到了以下错误ArrowInvalid:添加的列的长度必须与表的长度匹配。预期长度为6132，但实际长度为12264

Answer 1

根据documentation的说法

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假设你提供了一个list of Array。为了避免混淆，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()))