def fit(self, ds: loompy.LoomConnection, plot: str = None) -> np.ndarray:
"""
Fit a classifier and use it to determine cluster predictive power
Args:
ds Dataset
plot Filename for optional plot
Returns:
Matrix of classification probabilities, shape (n_cells, n_labels)
"""
logging.info("Feature selection")
nnz = ds.map([np.count_nonzero], axis=0)[0]
valid_genes = np.logical_and(nnz > 5, nnz < ds.shape[1] * 0.5).astype("int")
ds.ra._Valid = valid_genes
logging.info("Normalization")
normalizer = cg.Normalizer(False)
normalizer.fit(ds)
logging.info("Feature selection")
(_, enrichment, _) = cg.MarkerSelection(findq=False, labels_attr="Clusters").fit(ds)
genes = np.zeros_like(ds.ra.Gene, dtype=bool)
for ix in range(enrichment.shape[1]):
genes[np.argsort(-enrichment[:, ix])[:25]] = True
logging.info("PCA projection")
pca = cg.PCAProjection(genes, max_n_components=50)
transformed = pca.fit_transform(ds, normalizer)
le = LabelEncoder().fit(ds.ca.ClusterName)
self.le = le
labels = le.transform(ds.ca.ClusterName)
train_X, test_X, train_Y, test_Y = train_test_split(transformed, labels, test_size=0.2)
classifier = RandomForestClassifier(max_depth=30)
classifier.fit(train_X, train_Y)
self.report = classification_report(test_Y, classifier.predict(test_X), target_names=le.classes_)
self.proba = classifier.predict_proba(transformed)
if plot:
agg = npg.aggregate(labels, self.proba, axis=0, func="mean")
plt.imshow(agg, cmap="viridis")
plt.xticks(np.arange(le.classes_.shape[0]), le.classes_, rotation="vertical", fontsize=7)
plt.yticks(np.arange(le.classes_.shape[0]), le.classes_, rotation="horizontal", fontsize=7)
plt.xlabel("Predicted cell type")
plt.ylabel("Observed cell type")
plt.title("Predictive power of cluster identities")
cbar = plt.colorbar()
cbar.set_label('Average classification probability', rotation=90)
plt.savefig(plot, bbox_inches="tight")
return self.proba
def fit(
self, ds: loompy.LoomConnection
) -> Tuple[sparse.coo_matrix, sparse.coo_matrix, np.ndarray]:
"""
Discover the manifold
Returns:
knn The knn graph as a sparse matrix
mknn Mutual knn subgraph
pos 2D projection (gt-SNE) as ndarray with shape (n_cells, 2)
"""
n_cells = ds.shape[1]
logging.info("Processing all %d cells", n_cells)
logging.info("Validating genes")
nnz = ds.map([np.count_nonzero], axis=0)[0]
valid_genes = np.logical_and(nnz > 5,
nnz < ds.shape[1] * 0.5).astype("int")
ds.ra._Valid = valid_genes
logging.info("%d of %d genes were valid", np.sum(ds.ra._Valid == 1),
ds.shape[0])
logging.info("Normalization")
normalizer = cg.Normalizer(False)
normalizer.fit(ds)
logging.info("Selecting up to %d genes", self.n_genes)
genes = cg.FeatureSelection(self.n_genes).fit(ds,
mu=normalizer.mu,
sd=normalizer.sd)
logging.info("Loading data for selected genes")
data = np.zeros((n_cells, genes.shape[0]))
for (ix, selection, view) in ds.scan(axis=1):
data[selection - ix, :] = view[genes, :].T
logging.info("Computing initial subspace KNN")
subspaces = np.ones(data.shape)
knn = subspace_knn_graph(data, subspaces)
mknn = knn.minimum(knn.transpose()).tocoo()
for t in range(5):
logging.info(f"Refining subspace KNN (iteration {t + 1})")
logging.info("Louvain clustering")
graph = nx.from_scipy_sparse_matrix(mknn)
partitions = community.best_partition(graph)
labels = np.array(
[partitions[key] for key in range(mknn.shape[0])])
ds.ca.Clusters = labels
n_labels = np.max(labels) + 1
logging.info(f"Found {n_labels} clusters")
logging.info("Marker selection")
(_, enrichment, _) = cg.MarkerSelection(n_markers=10,
findq=False).fit(ds)
subspaces = np.zeros(data.shape)
for ix in range(enrichment.shape[1]):
for j in range(n_cells):
subspaces[j,
np.argsort(-enrichment[:, ix])[:self.n_genes //
n_labels]] = 1
knn = subspace_knn_graph(data, subspaces)
mknn = knn.minimum(knn.transpose()).tocoo()
perplexity = min(self.k, (n_cells - 1) / 3 - 1)
logging.info("gt-SNE layout")
# Note that perplexity argument is ignored in this case, but must still be given
# because bhtsne will check that it has a valid value
tsne_pos = cg.TSNE(perplexity=perplexity).layout(data, knn=knn.tocsr())
return (knn, mknn, tsne_pos)
def fit(self, ds: loompy.LoomConnection) -> Tuple[sparse.coo_matrix, sparse.coo_matrix, np.ndarray]:
"""
Discover the manifold
Args:
n_genes Number of genes to use for manifold learning (ignored if genes is not None)
gtsnse Use graph t-SNE for layout (default: standard tSNE)
alpha The scale parameter for multiscale KNN
genes List of genes to use for manifold learning
Returns:
knn The multiscale knn graph as a sparse matrix, with k = 100
mknn Mutual knn subgraph, with k = 20
pos 2D projection (t-SNE or gt-SNE) as ndarray with shape (n_cells, 2)
"""
n_valid = np.sum(ds.col_attrs["_Valid"] == 1)
n_total = ds.shape[1]
logging.info("%d of %d cells were valid", n_valid, n_total)
logging.info("%d of %d genes were valid", np.sum(ds.row_attrs["_Valid"] == 1), ds.shape[0])
cells = np.where(ds.col_attrs["_Valid"] == 1)[0]
logging.info("Normalization")
normalizer = cg.Normalizer(False)
normalizer.fit(ds)
if self.filter_cellcycle is not None:
cell_cycle_genes = np.array(open(self.filter_cellcycle).read().split())
mask = np.in1d(ds.ra.Gene, cell_cycle_genes)
if np.sum(mask) == 0:
logging.warn("None cell cycle genes where filtered, check your gene list")
else:
mask = None
if self.genes is None:
logging.info("Selecting up to %d genes", self.n_genes)
genes = cg.FeatureSelection(self.n_genes).fit(ds, mu=normalizer.mu, sd=normalizer.sd, mask=mask)
temp = np.zeros(ds.shape[0])
temp[genes] = 1
ds.set_attr("_Selected", temp, axis=0)
logging.info("%d genes selected", temp.sum())
n_components = min(50, n_valid)
logging.info("PCA projection to %d components", n_components)
pca = cg.PCAProjection(genes, max_n_components=n_components, layer=self.layer)
pca_transformed = pca.fit_transform(ds, normalizer, cells=cells)
transformed = pca_transformed
logging.info("Generating KNN graph")
k = min(10, n_valid - 1)
nn = NearestNeighbors(n_neighbors=k, algorithm="ball_tree", n_jobs=4)
nn.fit(transformed)
knn = nn.kneighbors_graph(mode='connectivity')
knn = knn.tocoo()
mknn = knn.minimum(knn.transpose()).tocoo()
logging.info("Louvain-Jaccard clustering")
lj = cg.LouvainJaccard(resolution=1)
labels = lj.fit_predict(knn)
# Make labels for excluded cells == -1
labels_all = np.zeros(ds.shape[1], dtype='int') + -1
labels_all[cells] = labels
ds.set_attr("Clusters", labels_all, axis=1)
n_labels = np.max(labels) + 1
logging.info("Found " + str(n_labels) + " LJ clusters")
logging.info("Marker selection")
(genes, _, _) = cg.MarkerSelection(n_markers=int(500 / n_labels), mask=mask).fit(ds)
else:
genes = self.genes
temp = np.zeros(ds.shape[0])
temp[genes] = 1
ds.set_attr("_Selected", temp, axis=0)
logging.info("%d genes selected", temp.sum())
n_components = min(50, n_valid)
logging.info("PCA projection to %d components", n_components)
pca = cg.PCAProjection(genes, max_n_components=n_components, layer=self.layer)
pca_transformed = pca.fit_transform(ds, normalizer, cells=cells)
transformed = pca_transformed
logging.info("Generating KNN graph")
k = min(10, n_valid - 1)
nn = NearestNeighbors(n_neighbors=k, algorithm="ball_tree", n_jobs=4)
nn.fit(transformed)
knn = nn.kneighbors_graph(mode='connectivity')
knn = knn.tocoo()
mknn = knn.minimum(knn.transpose()).tocoo()
logging.info("Louvain-Jaccard clustering")
lj = cg.LouvainJaccard(resolution=1)
labels = lj.fit_predict(knn)
# Make labels for excluded cells == -1
labels_all = np.zeros(ds.shape[1], dtype='int') + -1
labels_all[cells] = labels
ds.set_attr("Clusters", labels_all, axis=1)
n_labels = np.max(labels) + 1
logging.info("Found " + str(n_labels) + " LJ clusters")
logging.info("Marker selection")
(genes, _, _) = cg.MarkerSelection(n_markers=int(500 / n_labels)).fit(ds)
# Select cells across clusters more uniformly, preventing a single cluster from dominating the PCA
cells_adjusted = cg.cap_select(labels, cells, int(n_valid * 0.2))
n_components = min(50, cells_adjusted.shape[0])
logging.info("PCA projection to %d components", n_components)
pca = cg.PCAProjection(genes, max_n_components=n_components)
pca.fit(ds, normalizer, cells=cells_adjusted)
# Note that here we're transforming all cells; we just did the fit on the selection
transformed = pca.transform(ds, normalizer, cells=cells)
k = min(100, n_valid - 1)
logging.info("Generating multiscale KNN graph (k = %d)", k)
nn = NearestNeighbors(n_neighbors=k, algorithm="ball_tree", n_jobs=4)
nn.fit(transformed)
knn = nn.kneighbors(return_distance=False) # shape: (n_cells, k)
n_cells = knn.shape[0]
a = np.tile(np.arange(n_cells), k)
b = np.reshape(knn.T, (n_cells * k,))
w = np.repeat(1 / np.power(np.arange(1, k + 1), self.alpha), n_cells)
knn = sparse.coo_matrix((w, (a, b)), shape=(n_cells, n_cells))
threshold = w > 0.05
mknn = sparse.coo_matrix((w[threshold], (a[threshold], b[threshold])), shape=(n_cells, n_cells))
mknn = mknn.minimum(mknn.transpose()).tocoo()
perplexity = min(k, (n_valid - 1) / 3 - 1)
if self.gtsne:
logging.info("gt-SNE layout")
# Note that perplexity argument is ignored in this case, but must still be given
# because bhtsne will check that it has a valid value
tsne_pos = cg.TSNE(perplexity=perplexity).layout(transformed, knn=knn.tocsr())
else:
logging.info("t-SNE layout")
tsne_pos = cg.TSNE(perplexity=perplexity).layout(transformed)
tsne_all = np.zeros((ds.shape[1], 2), dtype='int') + np.min(tsne_pos, axis=0)
tsne_all[cells] = tsne_pos
# Transform back to the full set of cells
knn = sparse.coo_matrix((knn.data, (cells[knn.row], cells[knn.col])), shape=(n_total, n_total))
mknn = sparse.coo_matrix((mknn.data, (cells[mknn.row], cells[mknn.col])), shape=(n_total, n_total))
return (knn, mknn, tsne_all)
def fit(self, ds: loompy.LoomConnection, initial_pos: np.ndarray = None, nng: np.ndarray = None, blocked_genes: np.ndarray = None) -> Tuple[sparse.coo_matrix, sparse.coo_matrix, np.ndarray]:
"""
Discover the manifold
Args:
n_genes Number of genes to use for manifold learning (ignored if genes is not None)
gtsnse Use graph t-SNE for layout (default: standard tSNE)
alpha The scale parameter for multiscale KNN
genes List of genes to use for manifold learning
initial_pos Use this initial layout, shape (ds.shape[1], 2)
nng Non-neuronal genes, set these to zero in neurons (mask array)
blocked_gens Don't use these genes (mask array)
Returns:
knn The multiscale knn graph as a sparse matrix, with k = 100
mknn Mutual knn subgraph, with k = 20
pos 2D projection (t-SNE or gt-SNE) as ndarray with shape (n_cells, 2)
"""
n_cells = ds.shape[1]
logging.info("Processing all %d cells", n_cells)
logging.info("%d of %d genes were valid", np.sum(ds.row_attrs["_Valid"] == 1), ds.shape[0])
logging.info("Normalization")
normalizer = cg.Normalizer(False)
normalizer.fit(ds)
if self.filter_cellcycle is not None:
cell_cycle_genes = np.array(open(self.filter_cellcycle).read().split())
mask = np.in1d(ds.ra.Gene, cell_cycle_genes)
if np.sum(mask) == 0:
logging.warn("None cell cycle genes where filtered, check your gene list")
else:
mask = None
if blocked_genes is not None:
if mask is None:
mask = blocked_genes
else:
mask = mask & blocked_genes
if self.genes is None:
logging.info("Selecting up to %d genes", self.n_genes)
genes = cg.FeatureSelection(self.n_genes).fit(ds, mu=normalizer.mu, sd=normalizer.sd, mask=mask)
n_components = min(50, n_cells)
logging.info("PCA projection to %d components", n_components)
pca = cg.PCAProjection(genes, max_n_components=n_components)
pca_transformed = pca.fit_transform(ds, normalizer)
transformed = pca_transformed
logging.info("Generating balanced KNN graph")
np.random.seed(0)
k = min(self.k, n_cells - 1)
bnn = cg.BalancedKNN(k=k, maxl=2 * k, sight_k=2 * k)
bnn.fit(transformed)
knn = bnn.kneighbors_graph(mode='connectivity')
knn = knn.tocoo()
mknn = knn.minimum(knn.transpose()).tocoo()
logging.info("MKNN-Louvain clustering with outliers")
(a, b, w) = (mknn.row, mknn.col, mknn.data)
random.seed(13)
lj = cg.LouvainJaccard(resolution=1, jaccard=False)
labels = lj.fit_predict(knn)
bigs = np.where(np.bincount(labels) >= 10)[0]
mapping = {k: v for v, k in enumerate(bigs)}
labels = np.array([mapping[x] if x in bigs else -1 for x in labels])
n_labels = np.max(labels) + 1
logging.info("Found " + str(n_labels) + " clusters")
logging.info("Marker selection")
temp = None
if "Clusters" in ds.ca:
temp = ds.ca.Clusters
ds.ca.Clusters = labels - labels.min()
(genes, _, _) = cg.MarkerSelection(n_markers=int(500 / n_labels), mask=mask, findq=False).fit(ds)
if temp is not None:
ds.ca.Clusters = temp
else:
genes = self.genes
temp = np.zeros(ds.shape[0], dtype='bool')
temp[genes] = True
ds.ra._Selected = temp.astype('int')
logging.info("%d genes selected", temp.sum())
if self.genes is None:
# Select cells across clusters more uniformly, preventing a single cluster from dominating the PCA
cells_adjusted = cg.cap_select(labels - labels.min(), np.arange(n_cells), int(n_cells * 0.2))
n_components = min(50, cells_adjusted.shape[0])
logging.info("PCA projection to %d components", n_components)
pca = cg.PCAProjection(genes, max_n_components=n_components)
pca.fit(ds, normalizer, cells=cells_adjusted)
else:
n_components = min(50, n_cells)
logging.info("PCA projection to %d components", n_components)
pca = cg.PCAProjection(genes, max_n_components=n_components)
pca.fit(ds, normalizer)
# Note that here we're transforming all cells; we just did the fit on the selection
transformed = pca.transform(ds, normalizer)
k = min(self.k, n_cells - 1)
logging.info("Generating multiscale KNN graph (k = %d)", k)
bnn = cg.BalancedKNN(k=k, maxl=2 * k, sight_k=2 * k)
bnn.fit(transformed)
knn = bnn.kneighbors(mode='connectivity')[1][:, 1:]
n_cells = knn.shape[0]
a = np.tile(np.arange(n_cells), k)
b = np.reshape(knn.T, (n_cells * k,))
w = np.repeat(1 / np.power(np.arange(1, k + 1), self.alpha), n_cells)
knn = sparse.coo_matrix((w, (a, b)), shape=(n_cells, n_cells))
threshold = w > 0.025
mknn = sparse.coo_matrix((w[threshold], (a[threshold], b[threshold])), shape=(n_cells, n_cells))
mknn = mknn.minimum(mknn.transpose()).tocoo()
perplexity = min(k, (n_cells - 1) / 3 - 1)
if self.gtsne:
logging.info("gt-SNE layout")
# Note that perplexity argument is ignored in this case, but must still be given
# because bhtsne will check that it has a valid value
tsne_pos = cg.TSNE(perplexity=perplexity, max_iter=self.max_iter).layout(transformed, knn=knn.tocsr(), initial_pos=initial_pos)
else:
logging.info("t-SNE layout")
tsne_pos = cg.TSNE(perplexity=perplexity, max_iter=self.max_iter).layout(transformed, initial_pos=initial_pos)
return (knn, mknn, tsne_pos)
def aggregate(self,
ds: loompy.LoomConnection,
out_file: str,
agg_spec: Dict[str, str] = None) -> None:
if agg_spec is None:
agg_spec = {
"Age": "tally",
"Clusters": "first",
"Class": "mode",
"_Total": "mean",
"Sex": "tally",
"Tissue": "tally",
"SampleID": "tally",
"TissuePool": "first",
"Outliers": "mean"
}
cells = ds.col_attrs["Clusters"] >= 0
labels = ds.col_attrs["Clusters"][cells]
n_labels = len(set(labels))
logging.info("Aggregating clusters by mean")
cg.aggregate_loom(ds, out_file, None, "Clusters", "mean", agg_spec)
with loompy.connect(out_file) as dsout:
logging.info("Trinarizing")
if type(self.f) is list or type(self.f) is tuple:
for ix, f in enumerate(self.f):
trinaries = cg.Trinarizer(f=f).fit(ds)
if ix == 0:
dsout.layers["trinaries"] = trinaries
else:
dsout.layers[f"trinaries_{f}"] = trinaries
else:
trinaries = cg.Trinarizer(f=self.f).fit(ds)
dsout.layers["trinaries"] = trinaries
logging.info("Computing cluster gene enrichment scores")
(markers, enrichment,
qvals) = cg.MarkerSelection(self.n_markers).fit(ds)
dsout.layers["enrichment"] = enrichment
dsout.layers["enrichment_q"] = qvals
dsout.ca.NCells = np.bincount(labels, minlength=n_labels)
# Renumber the clusters
logging.info(
"Renumbering clusters by similarity, and permuting columns")
if "_Selected" in ds.ra:
genes = (ds.ra._Selected == 1)
else:
logging.info("Normalization")
normalizer = cg.Normalizer(False)
normalizer.fit(ds)
logging.info("Selecting up to 1000 genes")
genes = cg.FeatureSelection(1000).fit(ds,
mu=normalizer.mu,
sd=normalizer.sd)
data = np.log(dsout[:, :] + 1)[genes, :].T
D = pdist(data, 'euclidean')
Z = hc.linkage(D, 'ward')
optimal_Z = optimal_leaf_ordering(Z, D)
ordering = hc.leaves_list(optimal_Z)
# Permute the aggregated file, and renumber
dsout.permute(ordering, axis=1)
dsout.ca.Clusters = np.arange(n_labels)
# Renumber the original file, and permute
d = dict(zip(ordering, np.arange(n_labels)))
new_clusters = np.array(
[d[x] if x in d else -1 for x in ds.ca.Clusters])
ds.ca.Clusters = new_clusters
ds.permute(np.argsort(ds.col_attrs["Clusters"]), axis=1)
# Reorder the genes, markers first, ordered by enrichment in clusters
logging.info("Permuting rows")
mask = np.zeros(ds.shape[0], dtype=bool)
mask[markers] = True
# fetch enrichment from the aggregated file, so we get it already permuted on the column axis
gene_order = np.zeros(ds.shape[0], dtype='int')
gene_order[mask] = np.argmax(dsout.layer["enrichment"][mask, :],
axis=1)
gene_order[~mask] = np.argmax(dsout.layer["enrichment"][~mask, :],
axis=1) + dsout.shape[1]
gene_order = np.argsort(gene_order)
ds.permute(gene_order, axis=0)
dsout.permute(gene_order, axis=0)
data = trinaries[:, ordering][gene_order, :][:self.n_markers *
n_labels, :].T
cluster_scores = []
for ix in range(n_labels):
cluster_scores.append(data[ix, ix * 10:(ix + 1) * 10].sum())
dsout.ca.ClusterScore = np.array(cluster_scores)
def fit(
self, ds: loompy.LoomConnection
) -> Tuple[sparse.coo_matrix, sparse.coo_matrix, np.ndarray]:
"""
Discover the manifold
Args:
n_genes Number of genes to use for manifold learning (ignored if genes is not None)
gtsnse Use graph t-SNE for layout (default: standard tSNE)
alpha The scale parameter for multiscale KNN
genes List of genes to use for manifold learning
Returns:
knn The multiscale knn graph as a sparse matrix, with k = 100
mknn Mutual knn subgraph, with k = 20
pos 2D projection (t-SNE or gt-SNE) as ndarray with shape (n_cells, 2)
"""
n_cells = ds.shape[1]
logging.info("Processing all %d cells", n_cells)
logging.info("%d of %d genes were valid",
np.sum(ds.row_attrs["_Valid"] == 1), ds.shape[0])
logging.info("Normalization")
normalizer = cg.Normalizer(False)
normalizer.fit(ds)
if self.filter_cellcycle is not None:
cell_cycle_genes = np.array(
open(self.filter_cellcycle).read().split())
mask = np.in1d(ds.row_attrs["Gene"], cell_cycle_genes)
if np.sum(mask) == 0:
logging.warn(
"None cell cycle genes where filtered, check your gene list"
)
else:
mask = None
if self.genes is None:
logging.info("Selecting up to %d genes", self.n_genes)
genes = cg.FeatureSelection(self.n_genes).fit(ds,
mu=normalizer.mu,
sd=normalizer.sd,
mask=mask)
n_components = min(50, n_cells)
logging.info("PCA projection to %d components", n_components)
pca = cg.PCAProjection(genes, max_n_components=n_components)
pca_transformed = pca.fit_transform(ds, normalizer)
transformed = pca_transformed
logging.info("Generating balanced KNN graph")
k = min(self.k, n_cells - 1)
bnn = cg.BalancedKNN(k=k, maxl=2 * k)
bnn.fit(transformed)
knn = bnn.kneighbors_graph(mode='connectivity')
knn = knn.tocoo()
mknn = knn.minimum(knn.transpose()).tocoo()
logging.info("MKNN-Louvain clustering with outliers")
(a, b, w) = (mknn.row, mknn.col, mknn.data)
G = igraph.Graph(list(zip(a, b)),
directed=False,
edge_attrs={'weight': w})
VxCl = G.community_multilevel(return_levels=False,
weights="weight")
labels = np.array(VxCl.membership)
bigs = np.where(np.bincount(labels) >= 10)[0]
mapping = {k: v for v, k in enumerate(bigs)}
labels = np.array(
[mapping[x] if x in bigs else -1 for x in labels])
# Make labels for excluded cells == -1
ds.set_attr("Clusters", labels, axis=1)
n_labels = np.max(labels) + 1
logging.info("Found " + str(n_labels) + " clusters")
logging.info("Marker selection")
(genes, _,
_) = cg.MarkerSelection(n_markers=int(500 / n_labels)).fit(ds)
else:
genes = self.genes
temp = np.zeros(ds.shape[0])
temp[genes] = 1
ds.set_attr("_Selected", temp, axis=0)
logging.info("%d genes selected", temp.sum())
if self.genes is None:
# Select cells across clusters more uniformly, preventing a single cluster from dominating the PCA
cells_adjusted = cg.cap_select(labels - labels.min(),
np.arange(n_cells),
int(n_cells * 0.2))
n_components = min(50, cells_adjusted.shape[0])
logging.info("PCA projection to %d components", n_components)
pca = cg.PCAProjection(genes, max_n_components=n_components)
pca.fit(ds, normalizer, cells=cells_adjusted)
else:
n_components = min(50, n_cells)
logging.info("PCA projection to %d components", n_components)
pca = cg.PCAProjection(genes, max_n_components=n_components)
pca.fit(ds, normalizer)
# Note that here we're transforming all cells; we just did the fit on the selection
transformed = pca.transform(ds, normalizer)
k = min(self.k, n_cells - 1)
logging.info("Generating multiscale KNN graph (k = %d)", k)
bnn = cg.BalancedKNN(k=k, maxl=2 * k)
bnn.fit(transformed)
knn = bnn.kneighbors(mode='connectivity')[1][:, 1:]
n_cells = knn.shape[0]
a = np.tile(np.arange(n_cells), k)
b = np.reshape(knn.T, (n_cells * k, ))
w = np.repeat(1 / np.power(np.arange(1, k + 1), self.alpha), n_cells)
knn = sparse.coo_matrix((w, (a, b)), shape=(n_cells, n_cells))
threshold = w > 0.05
mknn = sparse.coo_matrix((w[threshold], (a[threshold], b[threshold])),
shape=(n_cells, n_cells))
mknn = mknn.minimum(mknn.transpose()).tocoo()
perplexity = min(k, (n_cells - 1) / 3 - 1)
if self.gtsne:
logging.info("gt-SNE layout")
# Note that perplexity argument is ignored in this case, but must still be given
# because bhtsne will check that it has a valid value
tsne_pos = cg.TSNE(perplexity=perplexity).layout(transformed,
knn=knn.tocsr())
else:
logging.info("t-SNE layout")
tsne_pos = cg.TSNE(perplexity=perplexity).layout(transformed)
return (knn, mknn, tsne_pos)