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packages/leann-backend-hnsw/third_party/faiss/tutorial/python/4-GPU.py

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+# Copyright (c) Meta Platforms, Inc. and affiliates.
+#
+# This source code is licensed under the MIT license found in the
+# LICENSE file in the root directory of this source tree.
+
+import numpy as np
+
+d = 64                           # dimension
+nb = 100000                      # database size
+nq = 10000                       # nb of queries
+np.random.seed(1234)             # make reproducible
+xb = np.random.random((nb, d)).astype('float32')
+xb[:, 0] += np.arange(nb) / 1000.
+xq = np.random.random((nq, d)).astype('float32')
+xq[:, 0] += np.arange(nq) / 1000.
+
+import faiss                     # make faiss available
+
+res = faiss.StandardGpuResources()  # use a single GPU
+
+## Using a flat index
+
+index_flat = faiss.IndexFlatL2(d)  # build a flat (CPU) index
+
+# make it a flat GPU index
+gpu_index_flat = faiss.index_cpu_to_gpu(res, 0, index_flat)
+
+gpu_index_flat.add(xb)         # add vectors to the index
+print(gpu_index_flat.ntotal)
+
+k = 4                          # we want to see 4 nearest neighbors
+D, I = gpu_index_flat.search(xq, k)  # actual search
+print(I[:5])                   # neighbors of the 5 first queries
+print(I[-5:])                  # neighbors of the 5 last queries
+
+
+## Using an IVF index
+
+nlist = 100
+quantizer = faiss.IndexFlatL2(d)  # the other index
+index_ivf = faiss.IndexIVFFlat(quantizer, d, nlist, faiss.METRIC_L2)
+# here we specify METRIC_L2, by default it performs inner-product search
+
+# make it an IVF GPU index
+gpu_index_ivf = faiss.index_cpu_to_gpu(res, 0, index_ivf)
+
+assert not gpu_index_ivf.is_trained
+gpu_index_ivf.train(xb)        # add vectors to the index
+assert gpu_index_ivf.is_trained
+
+gpu_index_ivf.add(xb)          # add vectors to the index
+print(gpu_index_ivf.ntotal)
+
+k = 4                          # we want to see 4 nearest neighbors
+D, I = gpu_index_ivf.search(xq, k)  # actual search
+print(I[:5])                   # neighbors of the 5 first queries
+print(I[-5:])                  # neighbors of the 5 last queries