Tony20100/langchain_full huggingface dataset:
# A RunnableSequence constructed using the `|` operator
sequence = RunnableLambda(lambda x: x + 1) | RunnableLambda(lambda x: x * 2)
sequence.invoke(1) # 4
sequence.batch([1, 2, 3]) # [4, 6, 8]
# A sequence that contains a RunnableParallel constructed using a dict literal
sequence = RunnableLambda(lambda x: x + 1) | {
    'mul_2': RunnableLambda(lambda x: x * 2),
    'mul_5': RunnableLambda(lambda x: x * 5)
}
sequence.invoke(1) # {'mul_2': 4, 'mul_5': 10}
Standard Methods¶
All Runnables expose additional methods that can be used to modify their behavior
(e.g., add a retry policy, add lifecycle listeners, make them configurable, etc.).
These methods will work on any Runnable, including Runnable chains constructed
by composing other Runnables. See the individual methods for details.
For example,
from langchain_core.runnables import RunnableLambda
import random
def add_one(x: int) -> int:
    return x + 1
def buggy_double(y: int) -> int:
    '''Buggy code that will fail 70% of the time'''
    if random.random() > 0.3:
        print('This code failed, and will probably be retried!')  # noqa: T201
        raise ValueError('Triggered buggy code')
    return y * 2
sequence = (
    RunnableLambda(add_one) |
    RunnableLambda(buggy_double).with_retry( # Retry on failure
        stop_after_attempt=10,
        wait_exponential_jitter=False
    )
)
print(sequence.input_schema.schema()) # Show inferred input schema
)
)
print(sequence.input_schema.schema()) # Show inferred input schema
print(sequence.output_schema.schema()) # Show inferred output schema
print(sequence.invoke(2)) # invoke the sequence (note the retry above!!)
Debugging and tracing¶
As the chains get longer, it can be useful to be able to see intermediate results
to debug and trace the chain.
You can set the global debug flag to True to enable debug output for all chains:
from langchain_core.globals import set_debug
set_debug(True)
Alternatively, you can pass existing or custom callbacks to any given chain:
from langchain_core.tracers import ConsoleCallbackHandler
chain.invoke(
    ...,
    config={'callbacks': [ConsoleCallbackHandler()]}
)
For a UI (and much more) checkout LangSmith: https://docs.smith.langchain.com/
Attributes
InputType
The type of input this runnable accepts specified as a type annotation.
OutputType
The type of output this runnable produces specified as a type annotation.
config_specs
List configurable fields for this runnable.
input_schema
The type of input this runnable accepts specified as a pydantic model.
name
The name of the runnable.
output_schema
The type of output this runnable produces specified as a pydantic model.
Methods
__init__()
abatch(inputs[, config, return_exceptions])
Default implementation runs ainvoke in parallel using asyncio.gather.
abatch_as_completed()
Run ainvoke in parallel on a list of inputs, yielding results as they complete.
ainvoke(input[, config])
Default implementation of ainvoke, calls invoke from a thread.
assign(**kwargs)
Assigns new fields to the dict output of this runnable.
astream(input[, config])
Default implementation of astream, which calls ainvoke.
astream(input[, config])
Default implementation of astream, which calls ainvoke.
astream_events(input[, config, ...])
[Beta] Generate a stream of events.
astream_log()
Stream all output from a runnable, as reported to the callback system.
atransform(input[, config])
Default implementation of atransform, which buffers input and calls astream.
batch(inputs[, config, return_exceptions])
Default implementation runs invoke in parallel using a thread pool executor.
batch_as_completed()
Run invoke in parallel on a list of inputs, yielding results as they complete.
bind(**kwargs)
Bind arguments to a Runnable, returning a new Runnable.
config_schema(*[, include])
The type of config this runnable accepts specified as a pydantic model.
get_graph([config])
Return a graph representation of this runnable.
get_input_schema([config])
Get a pydantic model that can be used to validate input to the runnable.
get_name([suffix, name])
Get the name of the runnable.
get_output_schema([config])
Get a pydantic model that can be used to validate output to the runnable.
get_prompts([config])
invoke(input[, config])
Transform a single input into an output.
map()
Return a new Runnable that maps a list of inputs to a list of outputs, by calling invoke() with each input.
pick(keys)
Pick keys from the dict output of this runnable.
pipe(*others[, name])
Compose this Runnable with Runnable-like objects to make a RunnableSequence.
stream(input[, config])
Default implementation of stream, which calls invoke.
transform(input[, config])
Default implementation of transform, which buffers input and then calls stream.
with_alisteners(*[, on_start, on_end, on_error])
with_alisteners(*[, on_start, on_end, on_error])
Bind asynchronous lifecycle listeners to a Runnable, returning a new Runnable.
with_config([config])
Bind config to a Runnable, returning a new Runnable.
with_fallbacks(fallbacks, *[, ...])
Add fallbacks to a runnable, returning a new Runnable.
with_listeners(*[, on_start, on_end, on_error])
Bind lifecycle listeners to a Runnable, returning a new Runnable.
with_retry(*[, retry_if_exception_type, ...])
Create a new Runnable that retries the original runnable on exceptions.
with_types(*[, input_type, output_type])
Bind input and output types to a Runnable, returning a new Runnable.
__init__()¶
async abatch(inputs: List[Input], config: Optional[Union[RunnableConfig, List[RunnableConfig]]] = None, *, return_exceptions: bool = False, **kwargs: Optional[Any]) → List[Output][source]¶
Default implementation runs ainvoke in parallel using asyncio.gather.
The default implementation of batch works well for IO bound runnables.
Subclasses should override this method if they can batch more efficiently;
e.g., if the underlying runnable uses an API which supports a batch mode.
Parameters
inputs (List[Input]) – 
config (Optional[Union[RunnableConfig, List[RunnableConfig]]]) – 
return_exceptions (bool) – 
kwargs (Optional[Any]) – 
Return type
List[Output]
async abatch_as_completed(inputs: Sequence[Input], config: Optional[Union[RunnableConfig, Sequence[RunnableConfig]]] = None, *, return_exceptions: Literal[False] = False, **kwargs: Optional[Any]) → AsyncIterator[Tuple[int, Output]][source]¶
async abatch_as_completed(inputs: Sequence[Input], config: Optional[Union[RunnableConfig, Sequence[RunnableConfig]]] = None, *, return_exceptions: Literal[True], **kwargs: Optional[Any]) → AsyncIterator[Tuple[int, Union[Output, Exception]]]
Run ainvoke in parallel on a list of inputs,
yielding results as they complete.
async ainvoke(input: Input, config: Optional[RunnableConfig] = None, **kwargs: Any) → Output[source]¶
Default implementation of ainvoke, calls invoke from a thread.
The default implementation allows usage of async code even if
the runnable did not implement a native async version of invoke.
Subclasses should override this method if they can run asynchronously.
Parameters
input (Input) – 
config (Optional[RunnableConfig]) – 
kwargs (Any) – 
Return type
Output
assign(**kwargs: Union[Runnable[Dict[str, Any], Any], Callable[[Dict[str, Any]], Any], Mapping[str, Union[Runnable[Dict[str, Any], Any], Callable[[Dict[str, Any]], Any]]]]) → RunnableSerializable[Any, Any][source]¶
Assigns new fields to the dict output of this runnable.
Returns a new runnable.
from langchain_community.llms.fake import FakeStreamingListLLM
from langchain_core.output_parsers import StrOutputParser
from langchain_core.prompts import SystemMessagePromptTemplate
from langchain_core.runnables import Runnable
from operator import itemgetter
prompt = (
    SystemMessagePromptTemplate.from_template("You are a nice assistant.")
    + "{question}"
)
llm = FakeStreamingListLLM(responses=["foo-lish"])
chain: Runnable = prompt | llm | {"str": StrOutputParser()}
chain_with_assign = chain.assign(hello=itemgetter("str") | llm)
chain_with_assign = chain.assign(hello=itemgetter("str") | llm)
print(chain_with_assign.input_schema.schema())
# {'title': 'PromptInput', 'type': 'object', 'properties':
{'question': {'title': 'Question', 'type': 'string'}}}
print(chain_with_assign.output_schema.schema()) #
{'title': 'RunnableSequenceOutput', 'type': 'object', 'properties':
{'str': {'title': 'Str',
'type': 'string'}, 'hello': {'title': 'Hello', 'type': 'string'}}}
Parameters
kwargs (Union[Runnable[Dict[str, Any], Any], Callable[[Dict[str, Any]], Any], Mapping[str, Union[Runnable[Dict[str, Any], Any], Callable[[Dict[str, Any]], Any]]]]) – 
Return type
RunnableSerializable[Any, Any]
async astream(input: Input, config: Optional[RunnableConfig] = None, **kwargs: Optional[Any]) → AsyncIterator[Output][source]¶
Default implementation of astream, which calls ainvoke.
Subclasses should override this method if they support streaming output.
Parameters
input (Input) – 
config (Optional[RunnableConfig]) – 
kwargs (Optional[Any]) – 
Return type
AsyncIterator[Output]
astream_events(input: Any, config: Optional[RunnableConfig] = None, *, version: Literal['v1', 'v2'], include_names: Optional[Sequence[str]] = None, include_types: Optional[Sequence[str]] = None, include_tags: Optional[Sequence[str]] = None, exclude_names: Optional[Sequence[str]] = None, exclude_types: Optional[Sequence[str]] = None, exclude_tags: Optional[Sequence[str]] = None, **kwargs: Any) → AsyncIterator[StreamEvent][source]¶
[Beta] Generate a stream of events.
exclude_names (Optional[Sequence[str]]) – Exclude events from runnables with matching names.
exclude_types (Optional[Sequence[str]]) – Exclude events from runnables with matching types.
exclude_tags (Optional[Sequence[str]]) – Exclude events from runnables with matching tags.
kwargs (Any) – Additional keyword arguments to pass to the runnable.
These will be passed to astream_log as this implementation
of astream_events is built on top of astream_log.
Returns
An async stream of StreamEvents.
Return type
AsyncIterator[StreamEvent]
Notes
async astream_log(input: Any, config: Optional[RunnableConfig] = None, *, diff: Literal[True] = True, with_streamed_output_list: bool = True, include_names: Optional[Sequence[str]] = None, include_types: Optional[Sequence[str]] = None, include_tags: Optional[Sequence[str]] = None, exclude_names: Optional[Sequence[str]] = None, exclude_types: Optional[Sequence[str]] = None, exclude_tags: Optional[Sequence[str]] = None, **kwargs: Any) → AsyncIterator[RunLogPatch][source]¶
async astream_log(input: Any, config: Optional[RunnableConfig] = None, *, diff: Literal[False], with_streamed_output_list: bool = True, include_names: Optional[Sequence[str]] = None, include_types: Optional[Sequence[str]] = None, include_tags: Optional[Sequence[str]] = None, exclude_names: Optional[Sequence[str]] = None, exclude_types: Optional[Sequence[str]] = None, exclude_tags: Optional[Sequence[str]] = None, **kwargs: Any) → AsyncIterator[RunLog]
Stream all output from a runnable, as reported to the callback system.
This includes all inner runs of LLMs, Retrievers, Tools, etc.
This includes all inner runs of LLMs, Retrievers, Tools, etc.
Output is streamed as Log objects, which include a list of
jsonpatch ops that describe how the state of the run has changed in each
step, and the final state of the run.
The jsonpatch ops can be applied in order to construct state.
Parameters
input – The input to the runnable.
config – The config to use for the runnable.
diff – Whether to yield diffs between each step, or the current state.
with_streamed_output_list – Whether to yield the streamed_output list.
include_names – Only include logs with these names.
include_types – Only include logs with these types.
include_tags – Only include logs with these tags.
exclude_names – Exclude logs with these names.
exclude_types – Exclude logs with these types.
exclude_tags – Exclude logs with these tags.
async atransform(input: AsyncIterator[Input], config: Optional[RunnableConfig] = None, **kwargs: Optional[Any]) → AsyncIterator[Output][source]¶
Default implementation of atransform, which buffers input and calls astream.
Subclasses should override this method if they can start producing output while
input is still being generated.
Parameters
input (AsyncIterator[Input]) – 
config (Optional[RunnableConfig]) – 
kwargs (Optional[Any]) – 
Return type
AsyncIterator[Output]
batch(inputs: List[Input], config: Optional[Union[RunnableConfig, List[RunnableConfig]]] = None, *, return_exceptions: bool = False, **kwargs: Optional[Any]) → List[Output][source]¶
Default implementation runs invoke in parallel using a thread pool executor.
The default implementation of batch works well for IO bound runnables.
Subclasses should override this method if they can batch more efficiently;
Subclasses should override this method if they can batch more efficiently;
e.g., if the underlying runnable uses an API which supports a batch mode.
Parameters
inputs (List[Input]) – 
config (Optional[Union[RunnableConfig, List[RunnableConfig]]]) – 
return_exceptions (bool) – 
kwargs (Optional[Any]) – 
Return type
List[Output]
batch_as_completed(inputs: Sequence[Input], config: Optional[Union[RunnableConfig, Sequence[RunnableConfig]]] = None, *, return_exceptions: Literal[False] = False, **kwargs: Any) → Iterator[Tuple[int, Output]][source]¶
batch_as_completed(inputs: Sequence[Input], config: Optional[Union[RunnableConfig, Sequence[RunnableConfig]]] = None, *, return_exceptions: Literal[True], **kwargs: Any) → Iterator[Tuple[int, Union[Output, Exception]]]
Run invoke in parallel on a list of inputs,
yielding results as they complete.
bind(**kwargs: Any) → Runnable[Input, Output][source]¶
Bind arguments to a Runnable, returning a new Runnable.
Useful when a runnable in a chain requires an argument that is not
in the output of the previous runnable or included in the user input.
Example:
from langchain_community.chat_models import ChatOllama
from langchain_core.output_parsers import StrOutputParser
llm = ChatOllama(model='llama2')
# Without bind.
chain = (
    llm
    | StrOutputParser()
)
chain.invoke("Repeat quoted words exactly: 'One two three four five.'")
# Output is 'One two three four five.'
# With bind.
chain = (
    llm.bind(stop=["three"])
    | StrOutputParser()
)
llm.bind(stop=["three"])
    | StrOutputParser()
)
chain.invoke("Repeat quoted words exactly: 'One two three four five.'")
# Output is 'One two'
Parameters
kwargs (Any) – 
Return type
Runnable[Input, Output]
config_schema(*, include: Optional[Sequence[str]] = None) → Type[BaseModel][source]¶
The type of config this runnable accepts specified as a pydantic model.
To mark a field as configurable, see the configurable_fields
and configurable_alternatives methods.
Parameters
include (Optional[Sequence[str]]) – A list of fields to include in the config schema.
Returns
A pydantic model that can be used to validate config.
Return type
Type[BaseModel]
get_graph(config: Optional[RunnableConfig] = None) → Graph[source]¶
Return a graph representation of this runnable.
Parameters
config (Optional[RunnableConfig]) – 
Return type
Graph
get_input_schema(config: Optional[RunnableConfig] = None) → Type[BaseModel][source]¶
Get a pydantic model that can be used to validate input to the runnable.
Runnables that leverage the configurable_fields and configurable_alternatives
methods will have a dynamic input schema that depends on which
configuration the runnable is invoked with.
This method allows to get an input schema for a specific configuration.
Parameters
config (Optional[RunnableConfig]) – A config to use when generating the schema.
Returns
A pydantic model that can be used to validate input.
Return type
Type[BaseModel]
get_name(suffix: Optional[str] = None, *, name: Optional[str] = None) → str[source]¶
Get the name of the runnable.
Parameters
suffix (Optional[str]) – 
name (Optional[str]) – 
Return type
suffix (Optional[str]) – 
name (Optional[str]) – 
Return type
str
get_output_schema(config: Optional[RunnableConfig] = None) → Type[BaseModel][source]¶
Get a pydantic model that can be used to validate output to the runnable.
Runnables that leverage the configurable_fields and configurable_alternatives
methods will have a dynamic output schema that depends on which
configuration the runnable is invoked with.
This method allows to get an output schema for a specific configuration.
Parameters
config (Optional[RunnableConfig]) – A config to use when generating the schema.
Returns
A pydantic model that can be used to validate output.
Return type
Type[BaseModel]
get_prompts(config: Optional[RunnableConfig] = None) → List[BasePromptTemplate][source]¶
Parameters
config (Optional[RunnableConfig]) – 
Return type
List[BasePromptTemplate]
abstract invoke(input: Input, config: Optional[RunnableConfig] = None) → Output[source]¶
Transform a single input into an output. Override to implement.
Parameters
input (Input) – The input to the runnable.
config (Optional[RunnableConfig]) – A config to use when invoking the runnable.
The config supports standard keys like ‘tags’, ‘metadata’ for tracing
purposes, ‘max_concurrency’ for controlling how much work to do
in parallel, and other keys. Please refer to the RunnableConfig
for more details.
Returns
The output of the runnable.
Return type
Output
map() → Runnable[List[Input], List[Output]][source]¶
Return a new Runnable that maps a list of inputs to a list of outputs,
by calling invoke() with each input.
Example
from langchain_core.runnables import RunnableLambda
def _lambda(x: int) -> int:
def _lambda(x: int) -> int:
    return x + 1
runnable = RunnableLambda(_lambda)
print(runnable.map().invoke([1, 2, 3])) # [2, 3, 4]
Return type
Runnable[List[Input], List[Output]]
pick(keys: Union[str, List[str]]) → RunnableSerializable[Any, Any][source]¶
Pick keys from the dict output of this runnable.
Pick single key:import json
from langchain_core.runnables import RunnableLambda, RunnableMap
as_str = RunnableLambda(str)
as_json = RunnableLambda(json.loads)
chain = RunnableMap(str=as_str, json=as_json)
chain.invoke("[1, 2, 3]")
# -> {"str": "[1, 2, 3]", "json": [1, 2, 3]}
json_only_chain = chain.pick("json")
json_only_chain.invoke("[1, 2, 3]")
# -> [1, 2, 3]
Pick list of keys:from typing import Any
import json
from langchain_core.runnables import RunnableLambda, RunnableMap
as_str = RunnableLambda(str)
as_json = RunnableLambda(json.loads)
def as_bytes(x: Any) -> bytes:
    return bytes(x, "utf-8")
chain = RunnableMap(
    str=as_str,
    json=as_json,
    bytes=RunnableLambda(as_bytes)
)
chain.invoke("[1, 2, 3]")
# -> {"str": "[1, 2, 3]", "json": [1, 2, 3], "bytes": b"[1, 2, 3]"}
json_and_bytes_chain = chain.pick(["json", "bytes"])
json_and_bytes_chain = chain.pick(["json", "bytes"])
json_and_bytes_chain.invoke("[1, 2, 3]")
# -> {"json": [1, 2, 3], "bytes": b"[1, 2, 3]"}
Parameters
keys (Union[str, List[str]]) – 
Return type
RunnableSerializable[Any, Any]
pipe(*others: Union[Runnable[Any, Other], Callable[[Any], Other]], name: Optional[str] = None) → RunnableSerializable[Input, Other][source]¶
Compose this Runnable with Runnable-like objects to make a RunnableSequence.
Equivalent to RunnableSequence(self, *others) or self | others[0] | …
Example
from langchain_core.runnables import RunnableLambda
def add_one(x: int) -> int:
    return x + 1
def mul_two(x: int) -> int:
    return x * 2
runnable_1 = RunnableLambda(add_one)
runnable_2 = RunnableLambda(mul_two)
sequence = runnable_1.pipe(runnable_2)
# Or equivalently:
# sequence = runnable_1 | runnable_2
# sequence = RunnableSequence(first=runnable_1, last=runnable_2)
sequence.invoke(1)
await sequence.ainvoke(1)
# -> 4
sequence.batch([1, 2, 3])
await sequence.abatch([1, 2, 3])
# -> [4, 6, 8]
Parameters
others (Union[Runnable[Any, Other], Callable[[Any], Other]]) – 
name (Optional[str]) – 
Return type
RunnableSerializable[Input, Other]
stream(input: Input, config: Optional[RunnableConfig] = None, **kwargs: Optional[Any]) → Iterator[Output][source]¶
Default implementation of stream, which calls invoke.
Subclasses should override this method if they support streaming output.
Parameters
input (Input) – 
config (Optional[RunnableConfig]) – 
kwargs (Optional[Any]) – 
Return type
Iterator[Output]
transform(input: Iterator[Input], config: Optional[RunnableConfig] = None, **kwargs: Optional[Any]) → Iterator[Output][source]¶
Default implementation of transform, which buffers input and then calls stream.
Subclasses should override this method if they can start producing output while
input is still being generated.
Parameters
input (Iterator[Input]) – 
config (Optional[RunnableConfig]) – 
kwargs (Optional[Any]) – 
Return type
Iterator[Output]
with_alisteners(*, on_start: Optional[AsyncListener] = None, on_end: Optional[AsyncListener] = None, on_error: Optional[AsyncListener] = None) → Runnable[Input, Output][source]¶
Bind asynchronous lifecycle listeners to a Runnable, returning a new Runnable.
on_start: Asynchronously called before the runnable starts running.
on_end: Asynchronously called after the runnable finishes running.
on_error: Asynchronously called if the runnable throws an error.
The Run object contains information about the run, including its id,
type, input, output, error, start_time, end_time, and any tags or metadata
added to the run.
Example:
Parameters
on_start (Optional[AsyncListener]) – 
on_end (Optional[AsyncListener]) – 
on_error (Optional[AsyncListener]) – 
Return type
Runnable[Input, Output]
with_config(config: Optional[RunnableConfig] = None, **kwargs: Any) → Runnable[Input, Output][source]¶
Bind config to a Runnable, returning a new Runnable.
Parameters
Bind config to a Runnable, returning a new Runnable.
Parameters
config (Optional[RunnableConfig]) – 
kwargs (Any) – 
Return type
Runnable[Input, Output]
with_fallbacks(fallbacks: Sequence[Runnable[Input, Output]], *, exceptions_to_handle: Tuple[Type[BaseException], ...] = (<class 'Exception'>,), exception_key: Optional[str] = None) → RunnableWithFallbacksT[Input, Output][source]¶
Add fallbacks to a runnable, returning a new Runnable.
Example
from typing import Iterator
from langchain_core.runnables import RunnableGenerator
def _generate_immediate_error(input: Iterator) -> Iterator[str]:
    raise ValueError()
    yield ""
def _generate(input: Iterator) -> Iterator[str]:
    yield from "foo bar"
runnable = RunnableGenerator(_generate_immediate_error).with_fallbacks(
    [RunnableGenerator(_generate)]
    )
print(''.join(runnable.stream({}))) #foo bar
Parameters
fallbacks (Sequence[Runnable[Input, Output]]) – A sequence of runnables to try if the original runnable fails.
exceptions_to_handle (Tuple[Type[BaseException], ...]) – A tuple of exception types to handle.
exception_key (Optional[str]) – If string is specified then handled exceptions will be passed
to fallbacks as part of the input under the specified key. If None,
exceptions will not be passed to fallbacks. If used, the base runnable
and its fallbacks must accept a dictionary as input.
Returns
A new Runnable that will try the original runnable, and then each
fallback in order, upon failures.
Return type
RunnableWithFallbacksT[Input, Output]