def neighbors(adata,
n_neighbors=30,
n_pcs=None,
use_rep=None,
knn=True,
random_state=0,
method='umap',
metric='euclidean',
metric_kwds={},
num_threads=-1,
copy=False):
"""
Compute a neighborhood graph of observations [McInnes18]_.
The neighbor search efficiency of this heavily relies on UMAP [McInnes18]_,
which also provides a method for estimating connectivities of data points -
the connectivity of the manifold (`method=='umap'`). If `method=='diffmap'`,
connectivities are computed according to [Coifman05]_, in the adaption of
[Haghverdi16]_.
Parameters
----------
adata
Annotated data matrix.
n_neighbors
The size of local neighborhood (in terms of number of neighboring data
points) used for manifold approximation. Larger values result in more
global views of the manifold, while smaller values result in more local
data being preserved. In general values should be in the range 2 to 100.
If `knn` is `True`, number of nearest neighbors to be searched. If `knn`
is `False`, a Gaussian kernel width is set to the distance of the
`n_neighbors` neighbor.
n_pcs : `int` or `None` (default: None)
Number of principal components to use.
If not specified, the full space is used of a pre-computed PCA,
or 30 components are used when PCA is computed internally.
use_rep : `None`, `'X'` or any key for `.obsm` (default: None)
Use the indicated representation. If `None`, the representation is chosen automatically:
for .n_vars < 50, .X is used, otherwise ‘X_pca’ is used.
knn
If `True`, use a hard threshold to restrict the number of neighbors to
`n_neighbors`, that is, consider a knn graph. Otherwise, use a Gaussian
Kernel to assign low weights to neighbors more distant than the
`n_neighbors` nearest neighbor.
random_state
A numpy random seed.
method : {{'umap', 'gauss', 'hnsw', 'sklearn', `None`}} (default: `'umap'`)
Use 'umap' [McInnes18]_ or 'gauss' (Gauss kernel following [Coifman05]_
with adaptive width [Haghverdi16]_) for computing connectivities.
metric
A known metric’s name or a callable that returns a distance.
metric_kwds
Options for the metric.
copy
Return a copy instead of writing to adata.
Returns
-------
Depending on `copy`, updates or returns `adata` with the following:
connectivities : sparse matrix (`.uns['neighbors']`, dtype `float32`)
Weighted adjacency matrix of the neighborhood graph of data
points. Weights should be interpreted as connectivities.
distances : sparse matrix (`.uns['neighbors']`, dtype `float32`)
Instead of decaying weights, this stores distances for each pair of
neighbors.
"""
adata = adata.copy() if copy else adata
if adata.isview: adata._init_as_actual(adata.copy())
if use_rep is None:
use_rep = 'X' if adata.n_vars < 50 or n_pcs is 0 else 'X_pca'
n_pcs = None if use_rep is 'X' else n_pcs
elif use_rep not in adata.obsm.keys(
) and 'X_' + use_rep in adata.obsm.keys():
use_rep = 'X_' + use_rep
if use_rep is 'X_pca':
if 'X_pca' not in adata.obsm.keys(
) or n_pcs is not None and n_pcs > adata.obsm['X_pca'].shape[1]:
pca(adata,
n_comps=30 if n_pcs is None else n_pcs,
svd_solver='arpack')
elif n_pcs is None and adata.obsm['X_pca'].shape[1] < 10:
logg.warn('Neighbors are computed on ',
adata.obsm['X_pca'].shape[1],
' principal components only.')
logg.info('computing neighbors', r=True)
if method is 'sklearn':
from sklearn.neighbors import NearestNeighbors
X = adata.X if use_rep is 'X' else adata.obsm[use_rep]
neighbors = NearestNeighbors(n_neighbors=n_neighbors,
metric=metric,
metric_params=metric_kwds,
n_jobs=num_threads)
neighbors.fit(X if n_pcs is None else X[:, :n_pcs])
knn_distances, neighbors.knn_indices = neighbors.kneighbors()
neighbors.distances, neighbors.connectivities = \
compute_connectivities_umap(neighbors.knn_indices, knn_distances, X.shape[0], n_neighbors=30)
elif method is 'hnsw':
X = adata.X if use_rep is 'X' else adata.obsm[use_rep]
neighbors = FastNeighbors(n_neighbors=n_neighbors,
num_threads=num_threads)
neighbors.fit(X if n_pcs is None else X[:, :n_pcs],
metric=metric,
random_state=random_state,
**metric_kwds)
else:
logg.switch_verbosity('off', module='scanpy')
with warnings.catch_warnings(
): # ignore numba warning (reported in umap/issues/252)
warnings.simplefilter("ignore")
neighbors = Neighbors(adata)
neighbors.compute_neighbors(n_neighbors=n_neighbors,
knn=knn,
n_pcs=n_pcs,
use_rep=use_rep,
method=method,
metric=metric,
metric_kwds=metric_kwds,
random_state=random_state,
write_knn_indices=True)
logg.switch_verbosity('on', module='scanpy')
adata.uns['neighbors'] = {}
adata.uns['neighbors']['params'] = {
'n_neighbors': n_neighbors,
'method': method
}
adata.uns['neighbors']['distances'] = neighbors.distances
adata.uns['neighbors']['connectivities'] = neighbors.connectivities
if hasattr(neighbors, 'knn_indices'):
adata.uns['neighbors']['indices'] = neighbors.knn_indices
logg.info(' finished',
time=True,
end=' ' if settings.verbosity > 2 else '\n')
logg.hint('added to `.uns[\'neighbors\']`\n'
' \'distances\', weighted adjacency matrix\n'
' \'connectivities\', weighted adjacency matrix')
return adata if copy else None
def neighbors(adata,
n_neighbors=30,
n_pcs=None,
use_rep=None,
knn=True,
random_state=0,
method='umap',
metric='euclidean',
metric_kwds={},
num_threads=-1,
copy=False):
"""
Compute a neighborhood graph of observations.
The neighbor graph methods (umap, hnsw, sklearn) only differ in runtime and yield the same result as scanpy [Wolf18]_.
Connectivities are computed with adaptive kernel width as proposed in Haghverdi et al. 2016 (doi:10.1038/nmeth.3971).
Parameters
----------
adata
Annotated data matrix.
n_neighbors
The size of local neighborhood (in terms of number of neighboring data
points) used for manifold approximation. Larger values result in more
global views of the manifold, while smaller values result in more local
data being preserved. In general values should be in the range 2 to 100.
If `knn` is `True`, number of nearest neighbors to be searched. If `knn`
is `False`, a Gaussian kernel width is set to the distance of the
`n_neighbors` neighbor.
n_pcs : `int` or `None` (default: None)
Number of principal components to use.
If not specified, the full space is used of a pre-computed PCA,
or 30 components are used when PCA is computed internally.
use_rep : `None`, `'X'` or any key for `.obsm` (default: None)
Use the indicated representation. If `None`, the representation is chosen automatically:
for .n_vars < 50, .X is used, otherwise ‘X_pca’ is used.
knn
If `True`, use a hard threshold to restrict the number of neighbors to
`n_neighbors`, that is, consider a knn graph. Otherwise, use a Gaussian
Kernel to assign low weights to neighbors more distant than the
`n_neighbors` nearest neighbor.
random_state
A numpy random seed.
method : {{'umap', 'hnsw', 'sklearn'}} (default: `'umap'`)
Method to compute neighbors, only differs in runtime.
The 'hnsw' method is most efficient and requires to `pip install hnswlib`.
Connectivities are computed with adaptive kernel width as proposed in Haghverdi et al. 2016 (https://doi.org/10.1038/nmeth.3971).
metric
A known metric’s name or a callable that returns a distance.
metric_kwds
Options for the metric.
copy
Return a copy instead of writing to adata.
Returns
-------
Depending on `copy`, updates or returns `adata` with the following:
connectivities : sparse matrix (`.uns['neighbors']`, dtype `float32`)
Weighted adjacency matrix of the neighborhood graph of data
points. Weights should be interpreted as connectivities.
distances : sparse matrix (`.uns['neighbors']`, dtype `float32`)
Instead of decaying weights, this stores distances for each pair of
neighbors.
"""
adata = adata.copy() if copy else adata
if use_rep is None:
use_rep = 'X' if adata.n_vars < 50 or n_pcs == 0 else 'X_pca'
n_pcs = None if use_rep == 'X' else n_pcs
elif use_rep not in adata.obsm.keys(
) and 'X_' + use_rep in adata.obsm.keys():
use_rep = 'X_' + use_rep
if use_rep == 'X_pca':
if 'X_pca' not in adata.obsm.keys(
) or n_pcs is not None and n_pcs > adata.obsm['X_pca'].shape[1]:
pca(adata,
n_comps=min(30 if n_pcs is None else n_pcs, adata.n_vars - 1),
svd_solver='arpack')
elif n_pcs is None and adata.obsm['X_pca'].shape[1] < 10:
logg.warn('Neighbors are computed on ',
adata.obsm['X_pca'].shape[1],
' principal components only.')
n_duplicate_cells = len(get_duplicate_cells(adata))
if n_duplicate_cells > 0:
logg.warn(
'You seem to have {} duplicate cells in your data.'.format(
n_duplicate_cells),
'Consider removing these via pp.remove_duplicate_cells.')
logg.info('computing neighbors', r=True)
if method == 'sklearn':
from sklearn.neighbors import NearestNeighbors
X = adata.X if use_rep == 'X' else adata.obsm[use_rep]
neighbors = NearestNeighbors(n_neighbors=n_neighbors - 1,
metric=metric,
metric_params=metric_kwds,
n_jobs=num_threads)
neighbors.fit(X if n_pcs is None else X[:, :n_pcs])
knn_distances, neighbors.knn_indices = neighbors.kneighbors()
knn_distances, neighbors.knn_indices = set_diagonal(
knn_distances, neighbors.knn_indices)
neighbors.distances, neighbors.connectivities = \
compute_connectivities_umap(neighbors.knn_indices, knn_distances, X.shape[0], n_neighbors=n_neighbors)
elif method == 'hnsw':
X = adata.X if use_rep == 'X' else adata.obsm[use_rep]
neighbors = FastNeighbors(n_neighbors=n_neighbors,
num_threads=num_threads)
neighbors.fit(X if n_pcs is None else X[:, :n_pcs],
metric=metric,
random_state=random_state,
**metric_kwds)
else:
logg.switch_verbosity('off', module='scanpy')
with warnings.catch_warnings(
): # ignore numba warning (reported in umap/issues/252)
warnings.simplefilter("ignore")
neighbors = Neighbors(adata)
neighbors.compute_neighbors(
n_neighbors=n_neighbors,
knn=knn,
n_pcs=n_pcs,
method=method,
use_rep=None if use_rep == 'X_pca' else use_rep,
random_state=random_state,
metric=metric,
metric_kwds=metric_kwds,
write_knn_indices=True)
logg.switch_verbosity('on', module='scanpy')
adata.uns['neighbors'] = {}
try:
adata.obsp['distances'] = neighbors.distances
adata.obsp['connectivities'] = neighbors.connectivities
adata.uns['neighbors']['connectivities_key'] = 'connectivities'
adata.uns['neighbors']['distances_key'] = 'distances'
except:
adata.uns['neighbors']['distances'] = neighbors.distances
adata.uns['neighbors']['connectivities'] = neighbors.connectivities
if hasattr(neighbors, 'knn_indices'):
adata.uns['neighbors']['indices'] = neighbors.knn_indices
adata.uns['neighbors']['params'] = {
'n_neighbors': n_neighbors,
'method': method,
'metric': metric,
'n_pcs': n_pcs
}
logg.info(' finished',
time=True,
end=' ' if settings.verbosity > 2 else '\n')
logg.hint(
'added \n'
' \'distances\' and \'connectivities\', weighted adjacency matrices (adata.obsp)'
)
return adata if copy else None
def neighbors(
adata,
n_neighbors=30,
n_pcs=None,
use_rep=None,
use_highly_variable=True,
knn=True,
random_state=0,
method="umap",
metric="euclidean",
metric_kwds=None,
num_threads=-1,
copy=False,
):
"""
Compute a neighborhood graph of observations.
The neighbor graph methods (umap, hnsw, sklearn) only differ in runtime and
yield the same result as scanpy [Wolf18]_. Connectivities are computed with
adaptive kernel width as proposed in Haghverdi et al. 2016 (doi:10.1038/nmeth.3971).
Parameters
----------
adata
Annotated data matrix.
n_neighbors
The size of local neighborhood (in terms of number of neighboring data
points) used for manifold approximation. Larger values result in more
global views of the manifold, while smaller values result in more local
data being preserved. In general values should be in the range 2 to 100.
If `knn` is `True`, number of nearest neighbors to be searched. If `knn`
is `False`, a Gaussian kernel width is set to the distance of the
`n_neighbors` neighbor.
n_pcs : `int` or `None` (default: None)
Number of principal components to use.
If not specified, the full space is used of a pre-computed PCA,
or 30 components are used when PCA is computed internally.
use_rep : `None`, `'X'` or any key for `.obsm` (default: None)
Use the indicated representation. If `None`, the representation is chosen
automatically: for .n_vars < 50, .X is used, otherwise ‘X_pca’ is used.
use_highly_variable: `bool` (default: True)
Whether to use highly variable genes only, stored in .var['highly_variable'].
knn
If `True`, use a hard threshold to restrict the number of neighbors to
`n_neighbors`, that is, consider a knn graph. Otherwise, use a Gaussian
Kernel to assign low weights to neighbors more distant than the
`n_neighbors` nearest neighbor.
random_state
A numpy random seed.
method : {{'umap', 'hnsw', 'sklearn'}} (default: `'umap'`)
Method to compute neighbors, only differs in runtime.
The 'hnsw' method is most efficient and requires to `pip install hnswlib`.
Connectivities are computed with adaptive kernel.
metric
A known metric’s name or a callable that returns a distance.
metric_kwds
Options for the metric.
num_threads
Number of threads to be used (for runtime).
copy
Return a copy instead of writing to adata.
Returns
-------
connectivities : `.obsp`
Sparse weighted adjacency matrix of the neighborhood graph of data
points. Weights should be interpreted as connectivities.
distances : `.obsp`
Sparse matrix of distances for each pair of neighbors.
"""
adata = adata.copy() if copy else adata
if use_rep is None:
use_rep = "X" if adata.n_vars < 50 or n_pcs == 0 else "X_pca"
n_pcs = None if use_rep == "X" else n_pcs
elif use_rep not in adata.obsm.keys() and f"X_{use_rep}" in adata.obsm.keys():
use_rep = f"X_{use_rep}"
if use_rep == "X_pca":
if (
"X_pca" not in adata.obsm.keys()
or n_pcs is not None
and n_pcs > adata.obsm["X_pca"].shape[1]
):
n_vars = (
np.sum(adata.var["highly_variable"])
if use_highly_variable and "highly_variable" in adata.var.keys()
else adata.n_vars
)
n_comps = min(30 if n_pcs is None else n_pcs, n_vars - 1, adata.n_obs - 1)
use_highly_variable &= "highly_variable" in adata.var.keys()
pca(
adata,
n_comps=n_comps,
use_highly_variable=use_highly_variable,
svd_solver="arpack",
)
elif n_pcs is None and adata.obsm["X_pca"].shape[1] < 10:
logg.warn(
f"Neighbors are computed on {adata.obsm['X_pca'].shape[1]} "
f"principal components only."
)
n_duplicate_cells = len(get_duplicate_cells(adata))
if n_duplicate_cells > 0:
logg.warn(
f"You seem to have {n_duplicate_cells} duplicate cells in your data.",
"Consider removing these via pp.remove_duplicate_cells.",
)
if metric_kwds is None:
metric_kwds = {}
logg.info("computing neighbors", r=True)
if method == "sklearn":
from sklearn.neighbors import NearestNeighbors
X = adata.X if use_rep == "X" else adata.obsm[use_rep]
neighbors = NearestNeighbors(
n_neighbors=n_neighbors - 1,
metric=metric,
metric_params=metric_kwds,
n_jobs=num_threads,
)
neighbors.fit(X if n_pcs is None else X[:, :n_pcs])
knn_distances, neighbors.knn_indices = neighbors.kneighbors()
knn_distances, neighbors.knn_indices = set_diagonal(
knn_distances, neighbors.knn_indices
)
neighbors.distances, neighbors.connectivities = compute_connectivities_umap(
neighbors.knn_indices, knn_distances, X.shape[0], n_neighbors=n_neighbors
)
elif method == "hnsw":
X = adata.X if use_rep == "X" else adata.obsm[use_rep]
neighbors = FastNeighbors(n_neighbors=n_neighbors, num_threads=num_threads)
neighbors.fit(
X if n_pcs is None else X[:, :n_pcs],
metric=metric,
random_state=random_state,
**metric_kwds,
)
else:
logg.switch_verbosity("off", module="scanpy")
with warnings.catch_warnings(): # ignore numba warning (umap/issues/252)
warnings.simplefilter("ignore")
neighbors = Neighbors(adata)
neighbors.compute_neighbors(
n_neighbors=n_neighbors,
knn=knn,
n_pcs=n_pcs,
method=method,
use_rep=use_rep,
random_state=random_state,
metric=metric,
metric_kwds=metric_kwds,
write_knn_indices=True,
)
logg.switch_verbosity("on", module="scanpy")
adata.uns["neighbors"] = {}
try:
adata.obsp["distances"] = neighbors.distances
adata.obsp["connectivities"] = neighbors.connectivities
adata.uns["neighbors"]["connectivities_key"] = "connectivities"
adata.uns["neighbors"]["distances_key"] = "distances"
except Exception:
adata.uns["neighbors"]["distances"] = neighbors.distances
adata.uns["neighbors"]["connectivities"] = neighbors.connectivities
if hasattr(neighbors, "knn_indices"):
adata.uns["neighbors"]["indices"] = neighbors.knn_indices
adata.uns["neighbors"]["params"] = {
"n_neighbors": n_neighbors,
"method": method,
"metric": metric,
"n_pcs": n_pcs,
"use_rep": use_rep,
}
logg.info(" finished", time=True, end=" " if settings.verbosity > 2 else "\n")
logg.hint(
"added \n"
" 'distances' and 'connectivities', weighted adjacency matrices (adata.obsp)"
)
return adata if copy else None