Resources
- RAFT Reference Documentation: API Documentation.
- RAFT Getting Started: Getting started with RAFT.
- Build and Install RAFT: Instructions for installing and building RAFT.
- RAPIDS Community: Get help, contribute, and collaborate.
- GitHub repository: Download the RAFT source code.
- Issue tracker: Report issues or request features.
Overview
RAFT contains fundamental widely-used algorithms and primitives for data science and machine learning. The algorithms are CUDA-accelerated and form building blocks for rapidly composing analytics.
By taking a primitives-based approach to algorithm development, RAFT
- accelerates algorithm construction time
- reduces the maintenance burden by maximizing reuse across projects, and
- centralizes core reusable computations, allowing future optimizations to benefit all algorithms that use them.
While not exhaustive, the following general categories help summarize the accelerated functions in RAFT:
Category | Examples |
---|---|
Data Formats | sparse & dense, conversions, data generation |
Dense Operations | linear algebra, matrix and vector operations, reductions, slicing, norms, factorization, least squares, svd & eigenvalue problems |
Sparse Operations | linear algebra, eigenvalue problems, slicing, norms, reductions, factorization, symmetrization, components & labeling |
Spatial | pairwise distances, nearest neighbors, neighborhood graph construction |
Basic Clustering | spectral clustering, hierarchical clustering, k-means |
Solvers | combinatorial optimization, iterative solvers |
Statistics | sampling, moments and summary statistics, metrics |
Tools & Utilities | common utilities for developing CUDA applications, multi-node multi-gpu infrastructure |
RAFT is a C++ header-only template library with an optional shared library that
- can speed up compile times for common template types, and
- provides host-accessible "runtime" APIs, which don't require a CUDA compiler to use
In addition being a C++ library, RAFT also provides 2 Python libraries:
pylibraft
- lightweight Python wrappers around RAFT's host-accessible "runtime" APIs.raft-dask
- multi-node multi-GPU communicator infrastructure for building distributed algorithms on the GPU with Dask.
Getting started
RAPIDS Memory Manager (RMM)
RAFT relies heavily on RMM which eases the burden of configuring different allocation strategies globally across the libraries that use it.
Multi-dimensional Arrays
The APIs in RAFT accept the mdspan multi-dimensional array view for representing data in higher dimensions similar to the ndarray
in the Numpy Python library. RAFT also contains the corresponding owning mdarray
structure, which simplifies the allocation and management of multi-dimensional data in both host and device (GPU) memory.
The mdarray
forms a convenience layer over RMM and can be constructed in RAFT using a number of different helper functions:
#include <raft/core/device_mdarray.hpp>
int n_rows = 10;
int n_cols = 10;
auto scalar = raft::make_device_scalar<float>(handle, 1.0);
auto vector = raft::make_device_vector<float>(handle, n_cols);
auto matrix = raft::make_device_matrix<float>(handle, n_rows, n_cols);
C++ Example
Most of the primitives in RAFT accept a raft::device_resources
object for the management of resources which are expensive to create, such CUDA streams, stream pools, and handles to other CUDA libraries like cublas
and cusolver
.
The example below demonstrates creating a RAFT handle and using it with device_matrix
and device_vector
to allocate memory, generating random clusters, and computing
pairwise Euclidean distances:
#include <raft/core/device_resources.hpp>
#include <raft/core/device_mdarray.hpp>
#include <raft/random/make_blobs.cuh>
#include <raft/distance/distance.cuh>
raft::device_resources handle;
int n_samples = 5000;
int n_features = 50;
auto input = raft::make_device_matrix<float, int>(handle, n_samples, n_features);
auto labels = raft::make_device_vector<int, int>(handle, n_samples);
auto output = raft::make_device_matrix<float, int>(handle, n_samples, n_samples);
raft::random::make_blobs(handle, input.view(), labels.view());
auto metric = raft::distance::DistanceType::L2SqrtExpanded;
raft::distance::pairwise_distance(handle, input.view(), input.view(), output.view(), metric);
It's also possible to create raft::device_mdspan
views to invoke the same API with raw pointers and shape information:
#include <raft/core/device_resources.hpp>
#include <raft/core/device_mdspan.hpp>
#include <raft/random/make_blobs.cuh>
#include <raft/distance/distance.cuh>
raft::device_resources handle;
int n_samples = 5000;
int n_features = 50;
float *input;
int *labels;
float *output;
...
// Allocate input, labels, and output pointers
...
auto input_view = raft::make_device_matrix_view(input, n_samples, n_features);
auto labels_view = raft::make_device_vector_view(labels, n_samples);
auto output_view = raft::make_device_matrix_view(output, n_samples, n_samples);
raft::random::make_blobs(handle, input_view, labels_view);
auto metric = raft::distance::DistanceType::L2SqrtExpanded;
raft::distance::pairwise_distance(handle, input_view, input_view, output_view, metric);
Python Example
The pylibraft
package contains a Python API for RAFT algorithms and primitives. pylibraft
integrates nicely into other libraries by being very lightweight with minimal dependencies and accepting any object that supports the __cuda_array_interface__
, such as CuPy's ndarray. The number of RAFT algorithms exposed in this package is continuing to grow from release to release.
The example below demonstrates computing the pairwise Euclidean distances between CuPy arrays. Note that CuPy is not a required dependency for pylibraft
.
import cupy as cp
from pylibraft.distance import pairwise_distance
n_samples = 5000
n_features = 50
in1 = cp.random.random_sample((n_samples, n_features), dtype=cp.float32)
in2 = cp.random.random_sample((n_samples, n_features), dtype=cp.float32)
output = pairwise_distance(in1, in2, metric="euclidean")
The output
array in the above example is of type raft.common.device_ndarray
, which supports cuda_array_interface making it interoperable with other libraries like CuPy, Numba, PyTorch and RAPIDS cuDF that also support it. CuPy supports DLPack, which also enables zero-copy conversion from raft.common.device_ndarray
to JAX and Tensorflow.
Below is an example of converting the output pylibraft.device_ndarray
to a CuPy array:
cupy_array = cp.asarray(output)
And converting to a PyTorch tensor:
import torch
torch_tensor = torch.as_tensor(output, device='cuda')
Or converting to a RAPIDS cuDF dataframe:
cudf_dataframe = cudf.DataFrame(output)
When the corresponding library has been installed and available in your environment, this conversion can also be done automatically by all RAFT compute APIs by setting a global configuration option:
import pylibraft.config
pylibraft.config.set_output_as("cupy") # All compute APIs will return cupy arrays
pylibraft.config.set_output_as("torch") # All compute APIs will return torch tensors
You can also specify a callable
that accepts a pylibraft.common.device_ndarray
and performs a custom conversion. The following example converts all output to numpy
arrays:
pylibraft.config.set_output_as(lambda device_ndarray: return device_ndarray.copy_to_host())
pylibraft
also supports writing to a pre-allocated output array so any __cuda_array_interface__
supported array can be written to in-place:
import cupy as cp
from pylibraft.distance import pairwise_distance
n_samples = 5000
n_features = 50
in1 = cp.random.random_sample((n_samples, n_features), dtype=cp.float32)
in2 = cp.random.random_sample((n_samples, n_features), dtype=cp.float32)
output = cp.empty((n_samples, n_samples), dtype=cp.float32)
pairwise_distance(in1, in2, out=output, metric="euclidean")
Installing
RAFT itself can be installed through conda, CMake Package Manager (CPM), pip, or by building the repository from source. Please refer to the build instructions for more a comprehensive guide on installing and building RAFT and using it in downstream projects.
Conda
The easiest way to install RAFT is through conda and several packages are provided.
libraft-headers
RAFT headerslibraft
(optional) shared library of pre-compiled template instantiations and runtime APIs.pylibraft
(optional) Python wrappers around RAFT algorithms and primitives.raft-dask
(optional) enables deployment of multi-node multi-GPU algorithms that use RAFTraft::comms
in Dask clusters.
Use the following command to install all of the RAFT packages with conda (replace rapidsai
with rapidsai-nightly
to install more up-to-date but less stable nightly packages). mamba
is preferred over the conda
command.
mamba install -c rapidsai -c conda-forge -c nvidia raft-dask pylibraft
You can also install the conda packages individually using the mamba
command above.
After installing RAFT, find_package(raft COMPONENTS compiled distributed)
can be used in your CUDA/C++ cmake build to compile and/or link against needed dependencies in your raft target. COMPONENTS
are optional and will depend on the packages installed.
Pip
pylibraft and raft-dask both have experimental packages that can be installed through pip:
pip install pylibraft-cu11 --extra-index-url=https://pypi.nvidia.com
pip install raft-dask-cu11 --extra-index-url=https://pypi.nvidia.com
CMake & CPM
RAFT uses the RAPIDS-CMake library, which makes it easy to include in downstream cmake projects. RAPIDS-CMake provides a convenience layer around CPM. Please refer to these instructions to install and use rapids-cmake in your project.
Example Template Project
You can find an example RAFT project template in the cpp/template
directory, which demonstrates how to build a new application with RAFT or incorporate RAFT into an existing cmake project.
CMake Targets
Additional CMake targets can be made available by adding components in the table below to the RAFT_COMPONENTS
list above, separated by spaces. The raft::raft
target will always be available. RAFT headers require, at a minimum, the CUDA toolkit libraries and RMM dependencies.
Component | Target | Description | Base Dependencies |
---|---|---|---|
n/a | raft::raft |
Full RAFT header library | CUDA toolkit, RMM, NVTX, CCCL, CUTLASS |
compiled | raft::compiled |
Pre-compiled template instantiations and runtime library | raft::raft |
distributed | raft::distributed |
Dependencies for raft::comms APIs |
raft::raft, UCX, NCCL |
Source
The easiest way to build RAFT from source is to use the build.sh
script at the root of the repository:
- Create an environment with the needed dependencies:
mamba env create --name raft_dev_env -f conda/environments/all_cuda-118_arch-x86_64.yaml
mamba activate raft_dev_env
./build.sh raft-dask pylibraft libraft tests bench --compile-lib
The build instructions contain more details on building RAFT from source and including it in downstream projects. You can also find a more comprehensive version of the above CPM code snippet the Building RAFT C++ from source section of the build instructions.
Folder Structure and Contents
The folder structure mirrors other RAPIDS repos, with the following folders:
ci
: Scripts for running CI in PRsconda
: Conda recipes and development conda environmentscpp
: Source code for C++ libraries.bench
: Benchmarks source codecmake
: CMake modules and templatesdoxygen
: Doxygen configurationinclude
: The C++ API headers are fully-contained here (deprecated directories are excluded from the listing below)cluster
: Basic clustering primitives and algorithms.comms
: A multi-node multi-GPU communications abstraction layer for NCCL+UCX and MPI+NCCL, which can be deployed in Dask clusters using theraft-dask
Python package.core
: Core API headers which require minimal dependencies aside from RMM and Cudatoolkit. These are safe to expose on public APIs and do not requirenvcc
to build. This is the same for any headers in RAFT which have the suffix*_types.hpp
.distance
: Distance primitiveslinalg
: Dense linear algebramatrix
: Dense matrix operationsneighbors
: Nearest neighbors and knn graph constructionrandom
: Random number generation, sampling, and data generation primitivessolver
: Iterative and combinatorial solvers for optimization and approximationsparse
: Sparse matrix operationsconvert
: Sparse conversion functionsdistance
: Sparse distance computationslinalg
: Sparse linear algebraneighbors
: Sparse nearest neighbors and knn graph constructionop
: Various sparse operations such as slicing and filtering (Note: this will soon be renamed tosparse/matrix
)solver
: Sparse solvers for optimization and approximation
stats
: Moments, summary statistics, model performance measuresutil
: Various reusable tools and utilities for accelerated algorithm development
internal
: A private header-only component that hosts the code shared between benchmarks and tests.scripts
: Helpful scripts for developmentsrc
: Compiled APIs and template instantiations for the shared librariestemplate
: A skeleton template containing the bare-bones file structure and cmake configuration for writing applications with RAFT.test
: Googletests source code
docs
: Source code and scripts for building library documentation (Uses breath, doxygen, & pydocs)python
: Source code for Python libraries.pylibraft
: Python build and source code for pylibraft libraryraft-dask
: Python build and source code for raft-dask library
thirdparty
: Third-party licenses
Contributing
If you are interested in contributing to the RAFT project, please read our Contributing guidelines. Refer to the Developer Guide for details on the developer guidelines, workflows, and principals.
References
When citing RAFT generally, please consider referencing this Github project.
@misc{rapidsai,
title={Rapidsai/raft: RAFT contains fundamental widely-used algorithms and primitives for data science, Graph and machine learning.},
url={https://github.com/rapidsai/raft},
journal={GitHub},
publisher={Nvidia RAPIDS},
author={Rapidsai},
year={2022}
}
If citing the sparse pairwise distances API, please consider using the following bibtex:
@article{nolet2021semiring,
title={Semiring primitives for sparse neighborhood methods on the gpu},
author={Nolet, Corey J and Gala, Divye and Raff, Edward and Eaton, Joe and Rees, Brad and Zedlewski, John and Oates, Tim},
journal={arXiv preprint arXiv:2104.06357},
year={2021}
}