add get_features_by_fid

pyogrio/_io.pyx

@@ -564,6 +564,64 @@ cdef get_features(
     return (geometries, field_data)
 
 
+@cython.boundscheck(False)  # Deactivate bounds checking
+@cython.wraparound(False)   # Deactivate negative indexing.
+cdef get_features_by_fid(
+    OGRLayerH ogr_layer,
+    int[:] fids,
+    object[:,:] fields,
+    encoding,
+    uint8_t read_geometry,
+    uint8_t force_2d):
+
+    cdef OGRFeatureH ogr_feature = NULL
+    cdef int n_fields
+    cdef int i
+    cdef int fid
+    cdef int field_index
+    cdef int count
+
+    # make sure layer is read from beginning
+    OGR_L_ResetReading(ogr_layer)
+
+    count = len(fids)
+
+    if read_geometry:
+        geometries = np.empty(shape=(count, ), dtype='object')
+        geom_view = geometries[:]
+
+    else:
+        geometries = None
+
+    n_fields = fields.shape[0]
+    field_indexes = fields[:,0]
+    field_ogr_types = fields[:,1]
+
+    field_data = [
+        np.empty(shape=(count, ),
+        dtype=fields[field_index,3]) for field_index in range(n_fields)
+    ]
+
+    field_data_view = [field_data[field_index][:] for field_index in range(n_fields)]
+
+    for i in range(count):
+        fid = fids[i]
+
+        ogr_feature = OGR_L_GetFeature(ogr_layer, fid)
+
+        if ogr_feature == NULL:
+            raise ValueError("Failed to read feature {}".format(i))
+
+        if read_geometry:
+            process_geometry(ogr_feature, i, geom_view, force_2d)
+
+        process_fields(
+            ogr_feature, i, n_fields, field_data, field_data_view, field_indexes, field_ogr_types, encoding
+        )
+
+    return (geometries, field_data)
+
+
 @cython.boundscheck(False)  # Deactivate bounds checking
 @cython.wraparound(False)   # Deactivate negative indexing.
 cdef get_bounds(
@@ -632,6 +690,7 @@ def ogr_read(
     int max_features=0,
     object where=None,
     tuple bbox=None,
+    object fids=None,
     **kwargs):
 
     cdef int err = 0
@@ -652,16 +711,23 @@ def ogr_read(
     ogr_dataset = ogr_open(path_c, 0, kwargs)
     ogr_layer = get_ogr_layer(ogr_dataset, layer)
 
-    # Apply the attribute filter
-    if where is not None and where != "":
-        apply_where_filter(ogr_layer, where)
+    if fids is not None:
+        if where is not None or bbox is not None or skip_features or max_features:
+            raise ValueError(
+                "cannot set both 'fids' and one of 'where', 'bbox', "
+                "'skip_features' or 'max_features'")
+        fids = np.asarray(fids, dtype=np.intc)
+    else:
+        # Apply the attribute filter
+        if where is not None and where != "":
+            apply_where_filter(ogr_layer, where)
 
-    # Apply the spatial filter
-    if bbox is not None:
-        apply_spatial_filter(ogr_layer, bbox)
+        # Apply the spatial filter
+        if bbox is not None:
+            apply_spatial_filter(ogr_layer, bbox)
 
-    # Limit feature range to available range
-    skip_features, max_features = validate_feature_range(ogr_layer, skip_features, max_features)
+        # Limit feature range to available range
+        skip_features, max_features = validate_feature_range(ogr_layer, skip_features, max_features)
 
     crs = get_crs(ogr_layer)
 
@@ -682,15 +748,26 @@ def ogr_read(
 
     geometry_type = get_geometry_type(ogr_layer)
 
-    geometries, field_data = get_features(
-        ogr_layer,
-        fields,
-        encoding,
-        read_geometry=read_geometry and geometry_type is not None,
-        force_2d=force_2d,
-        skip_features=skip_features,
-        max_features=max_features,
-    )
+    if fids is not None:
+        geometries, field_data = get_features_by_fid(
+            ogr_layer,
+            fids,
+            fields,
+            encoding,
+            read_geometry=read_geometry and geometry_type is not None,
+            force_2d=force_2d,
+        )
+
+    else:
+        geometries, field_data = get_features(
+            ogr_layer,
+            fields,
+            encoding,
+            read_geometry=read_geometry and geometry_type is not None,
+            force_2d=force_2d,
+            skip_features=skip_features,
+            max_features=max_features,
+        )
 
     meta = {
         'crs': crs,

pyogrio/_ogr.pxd

@@ -238,6 +238,7 @@ cdef extern from "ogr_api.h":
     int                     OGR_L_TestCapability(OGRLayerH layer, const char *name)
     OGRFeatureDefnH         OGR_L_GetLayerDefn(OGRLayerH layer)
     OGRFeatureH             OGR_L_GetNextFeature(OGRLayerH layer)
+    OGRFeatureH             OGR_L_GetFeature(OGRLayerH layer, int nFeatureId)
     void                    OGR_L_ResetReading(OGRLayerH layer)
     OGRErr                  OGR_L_SetAttributeFilter(OGRLayerH hLayer, const char* pszQuery)
     OGRErr                  OGR_L_SetNextByIndex(OGRLayerH layer, int nIndex)

pyogrio/geopandas.py

@@ -15,6 +15,7 @@ def read_dataframe(
     max_features=None,
     where=None,
     bbox=None,
+    fids=None,
 ):
     """Read from an OGR data source to a GeoPandas GeoDataFrame or Pandas DataFrame.
     If the data source does not have a geometry column or `read_geometry` is False,
@@ -90,6 +91,7 @@ def read_dataframe(
         max_features=max_features,
         where=where,
         bbox=bbox,
+        fids=fids,
     )
 
     columns = meta["fields"].tolist()

pyogrio/raw.py

@@ -26,6 +26,7 @@ def read(
     max_features=None,
     where=None,
     bbox=None,
+    fids=None,
 ):
     """Read OGR data source.
 
@@ -96,6 +97,7 @@ def read(
         max_features=max_features or 0,
         where=where,
         bbox=bbox,
+        fids=fids,
     )