[MRG] minor improvements to Index tests

doc/command-line.md

@@ -1621,3 +1621,68 @@ sig` commands will output to stdout.  So, for example,
 
 `sourmash sketch ... -o - | sourmash sig describe -` will describe the
 signatures that were just created.
+
+### Using manifests to explicitly refer to collections of files
+
+(sourmash v4.4.0 and later)
+
+Manifests are metadata catalogs of signatures that are used for
+signature selection and loading. They are used extensively by sourmash
+internals to speed up signature selection through picklists and
+pattern matching.
+
+Manifests can _also_ be used externally (via the command-line), and
+may be useful for organizing large collections of signatures.
+
+Suppose you have a large collection of signature (`.sig` or `.sig.gz`
+files) under a directory. You can create a manifest file for them like so:
+```
+sourmash sig manifest <dir> -o <dir>/manifest.csv
+```
+and then use the manifest directly for sourmash operations:
+```
+sourmash sig fileinfo <dir>/manifest.csv
+```
+This manifest can be used as a database target for most sourmash
+operations - search, gather, etc.  Note that manifests for directories
+must be placed beneath (and loaded from) the directory from which the
+manifest was generated; the specific manifest filename does not
+matter.
+
+A more advanced and slightly tricky way to use explicit manifest files
+is with lists of files.  If you create a file with a path list
+containing the locations of loadable sourmash collections, you can run
+`sourmash sig manifest pathlist.txt -o mf.csv` to generate a manifest
+of all of the files.  The resulting manifest in `mf.csv` can then be
+loaded directly.  This is very handy when you have many sourmash
+signatures, or large signature files.  The tricky part in doing this
+is that the manifest will store the same paths listed in the pathlist
+file - whether they are relative or absolute paths - and these paths
+must be resolvable by sourmash from the current working directory.
+This makes explicit manifests built from pathlist files less portable
+within or across systems than the other sourmash collections, which
+are all relocatable.
+
+For example, if you create a pathlist file `paths.txt` containing the
+following:
+```
+/path/to/zipfile.zip
+local_directory/some_signature.sig.gz
+local_dir2/
+```
+and then run:
+```
+sourmash sig manifest paths.txt -o mf.csv
+```
+you will be able to use `mf.csv` as a database for `sourmash search`
+and `sourmash gather` commands.  But, because it contains two relative paths,
+you will only be able to use it _from the directory that contains those
+two relative paths_.
+
+**Our advice:** We suggest using zip file collections for most
+situations; we primarily recommend using explicit manifests for
+situations where you have a **very large** collection of signatures
+(1000s or more), and don't want to make multiple copies of signatures
+in the collection (as you would have to, with a zipfile). This can be
+useful if you want to refer to different subsets of the collection
+without making multiple copies in a zip file.

src/sourmash/index/__init__.py

@@ -25,20 +25,22 @@
 
 ZipFileLinearIndex - simple on-disk storage of signatures.
 
-class MultiIndex - in-memory storage and selection of signatures from multiple
-index objects, using manifests.
+MultiIndex - in-memory storage and selection of signatures from multiple
+index objects, using manifests. All signatures are kept in memory.
 
 LazyLoadedIndex - selection on manifests with loading of index on demand.
 
+StandaloneManifestIndex - load manifests directly, and do lazy loading of
+signatures on demand. No signatures are kept in memory.
+
 CounterGather - an ancillary class returned by the 'counter_gather()' method.
 """
 
 import os
 import sourmash
 from abc import abstractmethod, ABC
 from collections import namedtuple, Counter
-import csv
-from io import TextIOWrapper
+from collections import defaultdict
 
 from ..search import make_jaccard_search_query, make_gather_query
 from ..manifest import CollectionManifest
@@ -49,7 +51,12 @@ class MultiIndex - in-memory storage and selection of signatures from multiple
 IndexSearchResult = namedtuple('Result', 'score, signature, location')
 
 class Index(ABC):
+    # this will be removed soon; see sourmash#1894.
     is_database = False
+
+    # 'manifest', when set, implies efficient selection and direct
+    # access to signatures. Signatures may be stored in the manifest
+    # or loaded on demand from disk depending on the class, however.
     manifest = None
 
     @abstractmethod
@@ -897,7 +904,6 @@ def _signatures_with_internal(self):
         CTB note: here, 'internal_location' is the source file for the
         index. This is a special feature of this (in memory) class.
         """
-        parent = self.parent
         for row in self.manifest.rows:
             yield row['signature'], row['internal_location']
 
@@ -931,8 +937,13 @@ def sigloc_iter():
                 for ss in idx.signatures():
                     yield ss, iloc
 
-        # build manifest; note, signatures are stored in memory.
+        # build manifest; note, ALL signatures are stored in memory.
         # CTB: could do this on demand?
+        # CTB: should we use get_manifest functionality?
+        # CTB: note here that the manifest is created by iteration
+        # *even if it already exists.* This could be changed to be more
+        # efficient... but for now, use StandaloneManifestIndex if you
+        # want to avoid this when loading from multiple files.
         manifest = CollectionManifest.create_manifest(sigloc_iter())
 
         # create!
@@ -945,6 +956,8 @@ def load_from_directory(cls, pathname, *, force=False):
         Takes directory path plus optional boolean 'force'. Attempts to
         load all files ending in .sig or .sig.gz, by default; if 'force' is
         True, will attempt to load _all_ files, ignoring errors.
+
+        Will not load anything other than JSON signature files.
         """
         from ..sourmash_args import traverse_find_sigs
 
@@ -962,11 +975,11 @@ def load_from_directory(cls, pathname, *, force=False):
 
                 rel = os.path.relpath(thisfile, pathname)
                 source_list.append(rel)
-            except (IOError, sourmash.exceptions.SourmashError):
+            except (IOError, sourmash.exceptions.SourmashError) as exc:
                 if force:
                     continue    # ignore error
                 else:
-                    raise       # stop loading!
+                    raise ValueError(exc)      # stop loading!
 
         # did we load anything? if not, error
         if not index_list:
@@ -1007,8 +1020,8 @@ def load_from_path(cls, pathname, force=False):
     def load_from_pathlist(cls, filename):
         """Create a MultiIndex from all files listed in a text file.
 
-        Note: this will load signatures from directories and databases, too,
-        if they are listed in the text file; it uses 'load_file_as_index'
+        Note: this will attempt to load signatures from each file,
+        including zip collections, etc; it uses 'load_file_as_index'
         underneath.
         """
         from ..sourmash_args import (load_pathlist_from_file,
@@ -1139,3 +1152,126 @@ def select(self, **kwargs):
         new_manifest = manifest.select_to_manifest(**kwargs)
 
         return LazyLoadedIndex(self.filename, new_manifest)
+
+
+class StandaloneManifestIndex(Index):
+    """Load a standalone manifest as an Index.
+
+    This class is useful for the situtation where you have a directory
+    with many signature collections underneath it, and you don't want to load
+    every collection each time you run sourmash.
+
+    Instead, you can run 'sourmash sig manifest <directory> -o mf.csv' to
+    output a manifest and then use this class to load 'mf.csv' directly.
+    Sketch type selection, picklists, and pattern matching will all work
+    directly on the manifest and will load signatures only upon demand.
+
+    One feature of this class is that absolute paths to sketches in
+    the 'internal_location' field of the manifests will be loaded properly.
+    This permits manifests to be constructed for various collections of
+    signatures that reside elsewhere, and not just below a single directory
+    prefix.
+
+    StandaloneManifestIndex does _not_ store signatures in memory.
+
+    This class overlaps in concept with LazyLoadedIndex and behaves
+    identically when a manifest contains only rows from a single
+    on-disk Index object.  However, unlike LazyLoadedIndex, this class
+    can be used to reference multiple on-disk Index objects.
+
+    This class also overlaps in concept with MultiIndex when
+    MultiIndex.load_from_pathlist is used to load other Index
+    objects. However, this class does not store any signatures in
+    memory, unlike MultiIndex.
+    """
+    is_database = True
+
+    def __init__(self, manifest, location, *, prefix=None):
+        """Create object. 'location' is path of manifest file, 'prefix' is
+        prepended to signature paths when loading non-abspaths."""
+        assert manifest is not None
+        self.manifest = manifest
+        self._location = location
+        self.prefix = prefix
+
+    @classmethod
+    def load(cls, location, *, prefix=None):
+        """Load manifest file from given location.
+
+        If prefix is None (default), it is automatically set from dirname.
+        Set prefix='' to avoid this, or provide an explicit prefix.
+        """
+        if not os.path.isfile(location):
+            raise ValueError(f"provided manifest location '{location}' is not a file")
+
+        with open(location, newline='') as fp:
+            m = CollectionManifest.load_from_csv(fp)
+
+        if prefix is None:
+            prefix = os.path.dirname(location)
+
+        return cls(m, location, prefix=prefix)
+
+    @property
+    def location(self):
+        "Return the path to this manifest."
+        return self._location
+
+    def signatures_with_location(self):
+        "Return an iterator over all signatures and their locations."
+        for ss, loc in self._signatures_with_internal():
+            yield ss, loc
+
+    def signatures(self):
+        "Return an iterator over all signatures."
+        for ss, loc in self._signatures_with_internal():
+            yield ss
+
+    def _signatures_with_internal(self):
+        """Return an iterator over all sigs of (sig, internal_location)
+
+        Note that this is implemented differently from most Index
+        objects in that it only lists subselected parts of the
+        manifest, and not the original manifest. This was done out of
+        convenience: we don't currently have access to the original
+        manifest in this class.
+        """
+        # collect all internal locations
+        iloc_to_rows = defaultdict(list)
+        for row in self.manifest.rows:
+            iloc = row['internal_location']
+            iloc_to_rows[iloc].append(row)
+
+        # iterate over internal locations, selecting relevant sigs
+        for iloc, iloc_rows in iloc_to_rows.items():
+            # prepend with prefix?
+            if not iloc.startswith('/') and self.prefix:
+                iloc = os.path.join(self.prefix, iloc)
+
+            sub_mf = CollectionManifest(iloc_rows)
+            picklist = sub_mf.to_picklist()
+
+            idx = sourmash.load_file_as_index(iloc)
+            idx = idx.select(picklist=picklist)
+            for ss in idx.signatures():
+                yield ss, iloc
+
+    def __len__(self):
+        "Number of signatures in this manifest (after any select)."
+        return len(self.manifest)
+
+    def __bool__(self):
+        "Is this manifest empty?"
+        return bool(self.manifest)
+
+    def save(self, *args):
+        raise NotImplementedError
+
+    def insert(self, *args):
+        raise NotImplementedError
+
+    def select(self, **kwargs):
+        "Run 'select' on the manifest."
+        new_manifest = self.manifest.select_to_manifest(**kwargs)
+        return StandaloneManifestIndex(new_manifest, self._location,
+                                       prefix=self.prefix)

src/sourmash/index/revindex.py

@@ -1,3 +1,7 @@
+"""
+RevIndex - a rust-based reverse index by hashes.
+"""
+
 import weakref
 
 from sourmash.index import Index, IndexSearchResult

src/sourmash/lca/lca_db.py

@@ -58,6 +58,10 @@ class LCA_Database(Index):
     """
     is_database = True
 
+    # we set manifest to None to avoid implication of fast on-disk access to
+    # sketches. This may be revisited later.
+    manifest = None
+
     def __init__(self, ksize, scaled, moltype='DNA'):
         self.ksize = int(ksize)
         self.scaled = int(scaled)

src/sourmash/sourmash_args.py

@@ -364,6 +364,12 @@ def _load_stdin(filename, **kwargs):
     return db
 
 
+def _load_standalone_manifest(filename, **kwargs):
+    from sourmash.index import StandaloneManifestIndex
+    idx = StandaloneManifestIndex.load(filename)
+    return idx
+
+
 def _multiindex_load_from_pathlist(filename, **kwargs):
     "Load collection from a list of signature/database files"
     db = MultiIndex.load_from_pathlist(filename)
@@ -416,6 +422,7 @@ def _load_zipfile(filename, **kwargs):
 # all loader functions, in order.
 _loader_functions = [
     ("load from stdin", _load_stdin),
+    ("load from standalone manifest", _load_standalone_manifest),
     ("load from path (file or directory)", _multiindex_load_from_path),
     ("load from file list", _multiindex_load_from_pathlist),
     ("load SBT", _load_sbt),

tests/test-data/scaled/mf.csv

@@ -0,0 +1,17 @@
+# SOURMASH-MANIFEST-VERSION: 1.0
+internal_location,md5,md5short,ksize,moltype,num,scaled,n_hashes,with_abundance,name,filename
+all.lca.json,455c2f95f2d0a95e176870659119f170,455c2f95,31,DNA,0,10000,93,0,,
+all.lca.json,684aa226f843eaa7e1e40fc5603d5f2a,684aa226,31,DNA,0,10000,48,0,,
+all.lca.json,7f7835d2dd27ba703e843eee4757f3c2,7f7835d2,31,DNA,0,10000,8,0,,
+all.lca.json,7ffcfaa4027d4153a991b6bd78cf39fe,7ffcfaa4,31,DNA,0,10000,45,0,,
+all.lca.json,d84ef28f610b1783f801734699cf7e40,d84ef28f,31,DNA,0,10000,45,0,,
+genome-s10+s11.fa.gz.sig,455c2f95f2d0a95e176870659119f170,455c2f95,31,DNA,0,10000,93,0,,../genome-s10+s11.fa.gz
+genome-s11.fa.gz.sig,7ffcfaa4027d4153a991b6bd78cf39fe,7ffcfaa4,31,DNA,0,10000,45,0,,../genome-s11.fa.gz
+all.sbt.zip,684aa226f843eaa7e1e40fc5603d5f2a,684aa226,31,DNA,0,10000,48,0,,../genome-s10.fa.gz
+all.sbt.zip,7f7835d2dd27ba703e843eee4757f3c2,7f7835d2,31,DNA,0,10000,8,0,,../genome-s10-small.fa.gz
+all.sbt.zip,7ffcfaa4027d4153a991b6bd78cf39fe,7ffcfaa4,31,DNA,0,10000,45,0,,../genome-s11.fa.gz
+all.sbt.zip,455c2f95f2d0a95e176870659119f170,455c2f95,31,DNA,0,10000,93,0,,../genome-s10+s11.fa.gz
+all.sbt.zip,d84ef28f610b1783f801734699cf7e40,d84ef28f,31,DNA,0,10000,45,0,,../genome-s12.fa.gz
+genome-s10-small.fa.gz.sig,7f7835d2dd27ba703e843eee4757f3c2,7f7835d2,31,DNA,0,10000,8,0,,../genome-s10-small.fa.gz
+genome-s12.fa.gz.sig,d84ef28f610b1783f801734699cf7e40,d84ef28f,31,DNA,0,10000,45,0,,../genome-s12.fa.gz
+genome-s10.fa.gz.sig,684aa226f843eaa7e1e40fc5603d5f2a,684aa226,31,DNA,0,10000,48,0,,../genome-s10.fa.gz

tests/test-data/scaled/pathlist.txt

@@ -0,0 +1,7 @@
+all.lca.json
+all.sbt.zip
+genome-s10+s11.fa.gz.sig
+genome-s10-small.fa.gz.sig
+genome-s10.fa.gz.sig
+genome-s11.fa.gz.sig
+genome-s12.fa.gz.sig