pyarrow.Schema¶

class pyarrow.Schema¶

Bases: pyarrow.lib._Weakrefable

__init__(*args, **kwargs)¶: Initialize self. See help(type(self)) for accurate signature.

Methods

`__init__`(args, *kwargs)	Initialize self.
`add_metadata`(self, metadata)
`append`(self, Field field)	Append a field at the end of the schema.
`empty_table`(self)	Provide an empty table according to the schema.
`equals`(self, Schema other, …)	Test if this schema is equal to the other
`field`(self, i)	Select a field by its column name or numeric index.
`field_by_name`(self, name)	Access a field by its name rather than the column index.
`from_pandas`(type cls, df[, preserve_index])	Returns implied schema from dataframe
`get_all_field_indices`(self, name)	Return sorted list of indices for fields with the given name
`get_field_index`(self, name)	Return index of field with given unique name.
`insert`(self, int i, Field field)	Add a field at position i to the schema.
`remove`(self, int i)	Remove the field at index i from the schema.
`remove_metadata`(self)	Create new schema without metadata, if any
`serialize`(self[, memory_pool])	Write Schema to Buffer as encapsulated IPC message
`set`(self, int i, Field field)	Replace a field at position i in the schema.
`to_string`(self[, truncate_metadata, …])	Return human-readable representation of Schema
`with_metadata`(self, metadata)	Add metadata as dict of string keys and values to Schema

Attributes

`metadata`
`names`	The schema’s field names.
`pandas_metadata`	Return deserialized-from-JSON pandas metadata field (if it exists)
`types`	The schema’s field types.

add_metadata(self, metadata)¶

append(self, Field field)¶

Append a field at the end of the schema.

In contrast to Python’s list.append() it does return a new object, leaving the original Schema unmodified.

Parameters: field (Field) –
Returns: schema (Schema) – New object with appended field.

empty_table(self)¶

Provide an empty table according to the schema.

Returns: table (pyarrow.Table)

equals(self, Schema other, bool check_metadata=False)¶

Test if this schema is equal to the other

Parameters

other (pyarrow.Schema) –
check_metadata (bool, default False) – Key/value metadata must be equal too

Returns

is_equal (bool)

field(self, i)¶

Select a field by its column name or numeric index.

Parameters: i (int or string) –
Returns: pyarrow.Field

field_by_name(self, name)¶

Access a field by its name rather than the column index.

Parameters: name (str) –
Returns: field (pyarrow.Field)

from_pandas(type cls, df, preserve_index=None)¶

Returns implied schema from dataframe

Parameters

df (pandas.DataFrame) –
preserve_index (bool, default True) – Whether to store the index as an additional column (or columns, for MultiIndex) in the resulting Table. The default of None will store the index as a column, except for RangeIndex which is stored as metadata only. Use preserve_index=True to force it to be stored as a column.

Returns

pyarrow.Schema

Examples

>>> import pandas as pd
>>> import pyarrow as pa
>>> df = pd.DataFrame({
    ...     'int': [1, 2],
    ...     'str': ['a', 'b']
    ... })
>>> pa.Schema.from_pandas(df)
int: int64
str: string
__index_level_0__: int64

get_all_field_indices(self, name)¶: Return sorted list of indices for fields with the given name

get_field_index(self, name)¶: Return index of field with given unique name. Returns -1 if not found or if duplicated

insert(self, int i, Field field)¶

Add a field at position i to the schema.

Parameters

i (int) –
field (Field) –

Returns

schema (Schema)

metadata¶

names¶

The schema’s field names.

Returns: list of str

pandas_metadata¶: Return deserialized-from-JSON pandas metadata field (if it exists)

remove(self, int i)¶

Remove the field at index i from the schema.

Parameters: i (int) –
Returns: schema (Schema)

remove_metadata(self)¶

Create new schema without metadata, if any

Returns: schema (pyarrow.Schema)

serialize(self, memory_pool=None)¶

Write Schema to Buffer as encapsulated IPC message

Parameters: memory_pool (MemoryPool, default None) – Uses default memory pool if not specified
Returns: serialized (Buffer)

set(self, int i, Field field)¶

Replace a field at position i in the schema.

Parameters

i (int) –
field (Field) –

Returns

schema (Schema)

to_string(self, truncate_metadata=True, show_field_metadata=True, show_schema_metadata=True)¶

Return human-readable representation of Schema

Parameters

truncate_metadata (boolean, default True) – Limit metadata key/value display to a single line of ~80 characters or less
show_field_metadata (boolean, default True) – Display Field-level KeyValueMetadata
show_schema_metadata (boolean, default True) – Display Schema-level KeyValueMetadata

Returns

str (the formatted output)

types¶

The schema’s field types.

Returns: list of DataType

with_metadata(self, metadata)¶

Add metadata as dict of string keys and values to Schema

Parameters: metadata (dict) – Keys and values must be string-like / coercible to bytes
Returns: schema (pyarrow.Schema)

pyarrow.Field pyarrow.ExtensionType