Schema

class

class Schema

Categories: attributes

Ordered mapping of column name to data type.

Returned by TableFrame.schema. Iterates in column order and supports mapping access (schema["col"], "col" in schema, len(schema)) plus the query helpers below.

Examples

tf.schema["a"]
tf.schema.names()

Methods

method

clear

def clear(*args = (), **kwargs = {})

Remove all entries, leaving an empty schema.

Parameters:

parameter

*args

parameter

**kwargs

method

copy

def copy(*args = (), **kwargs = {})

Return a shallow copy of this schema.

Parameters:

parameter

*args

parameter

**kwargs

method

fromkeys

def fromkeys(iterable, value = None)

Build a schema from the given names, all with the same data type.

Parameters:

parameter

iterable

parameter

value

method

get

def get(key, default = None)

Return the data type for key, or default if absent.

Parameters:

parameter

key

parameter

default

Example:

tf.schema.get("a")

A default keeps the lookup total when the column may be absent:

tf.schema.get("missing", String)

method

items

def items(*args = (), **kwargs = {})

Return the (name, data type) pairs, in column order.

Parameters:

parameter

*args

parameter

**kwargs

Example:

[(name, dtype) for name, dtype in tf.schema.items()]

method

keys

def keys(*args = (), **kwargs = {})

Return the column names, in column order.

Parameters:

parameter

*args

parameter

**kwargs

Example:

list(tf.schema.keys())

method

move_to_end

def move_to_end(key, last = True)

Move column key to the end (or the start when last is False).

Parameters:

parameter

key

parameter

last

method

pop

def pop(*args = (), **kwargs = {})

Remove column key and return its data type.

Parameters:

parameter

*args

parameter

**kwargs

method

popitem

def popitem(last = True)

Remove and return the last (or first) (name, data type) pair.

Parameters:

parameter

last

method

setdefault

def setdefault(key, default = None)

Return key's data type, inserting default if it is absent.

Parameters:

parameter

key

parameter

default

method

update

def update(*args = (), **kwargs = {})

Update this schema in place from another mapping of columns.

Parameters:

parameter

*args

parameter

**kwargs

method

values

def values(*args = (), **kwargs = {})

Return the data types, in column order.

Parameters:

parameter

*args

parameter

**kwargs

Example:

list(tf.schema.values())

method

names

def names() -> list[str]

Return the column names, in column order.

Example:

tf.schema.names()

method

dtypes

def dtypes() -> list[DataType]

Return the column data types, in column order.

Example:

tf.schema.dtypes()

method

to_arrow

def to_arrow(*, compat_level: None = None) -> Any

Return this schema as a PyArrow schema.

Parameters:

parameter

compat_levelNone

Example:

tf.schema.to_arrow()

method

to_frame

def to_frame() -> TableFrame

Return an empty TableFrame having exactly this schema.

Example:

tf.schema.to_frame()

method

len

def len() -> int

Return the number of columns.

Example:

tf.schema.len()

method

to_python

def to_python() -> dict[str, type]

Return a dict mapping each column name to its Python type.

Example:

tf.schema.to_python()["a"]  # <class 'int'>

method

contains_dtype

def contains_dtype(dtype: DataType, *, recursive: bool) -> bool

Return whether any column has the given data type.

Parameters:

parameter

dtypeDataType

Data type to look for.

parameter

recursivebool

Also match the type nested inside List / Struct / Array columns.

Example:

tf.schema.contains_dtype(String, recursive=False)

recursive=True also looks inside List / Struct / Array columns:

tf.schema.contains_dtype(String, recursive=True)