Allow reading individual file extensions via filepaths

Author: karimbahgat

README.md

@@ -244,7 +244,11 @@ OR
 	>>> sf = shapefile.Reader("shapefiles/blockgroups.dbf")
 
 OR any of the other 5+ formats which are potentially part of a shapefile. The
-library does not care about file extensions.
+library does not care about file extensions. You can also specify that you only 
+want to read some of the file extensions through the use of keyword arguments:
+
+
+	>>> sf = shapefile.Reader(dbf="shapefiles/blockgroups.dbf")
 
 #### Reading Shapefiles from Zip Files
 

shapefile.py

@@ -1043,7 +1043,7 @@ def __init__(self, *args, **kwargs):
                     self.load(path)
                     return
 
-        # Otherwise, load from separate shp/shx/dbf args (must be file-like)
+        # Otherwise, load from separate shp/shx/dbf args (must be path or file-like)
         if "shp" in kwargs.keys():
             if hasattr(kwargs["shp"], "read"):
                 self.shp = kwargs["shp"]
@@ -1053,7 +1053,8 @@ def __init__(self, *args, **kwargs):
                 except (NameError, io.UnsupportedOperation):
                     self.shp = io.BytesIO(self.shp.read())
             else:
-                raise ShapefileException('The shp arg must be file-like.')
+                (baseName, ext) = os.path.splitext(kwargs["shp"])
+                self.load_shp(baseName)
 
             if "shx" in kwargs.keys():
                 if hasattr(kwargs["shx"], "read"):
@@ -1064,7 +1065,8 @@ def __init__(self, *args, **kwargs):
                     except (NameError, io.UnsupportedOperation):
                         self.shx = io.BytesIO(self.shx.read())
                 else:
-                    raise ShapefileException('The shx arg must be file-like.')
+                    (baseName, ext) = os.path.splitext(kwargs["shx"])
+                    self.load_shx(baseName)
 
         if "dbf" in kwargs.keys():
             if hasattr(kwargs["dbf"], "read"):
@@ -1075,7 +1077,8 @@ def __init__(self, *args, **kwargs):
                 except (NameError, io.UnsupportedOperation):
                     self.dbf = io.BytesIO(self.dbf.read())
             else:
-                raise ShapefileException('The dbf arg must be file-like.')
+                (baseName, ext) = os.path.splitext(kwargs["dbf"])
+                self.load_dbf(baseName)
 
         # Load the files
         if self.shp or self.dbf:

test_shapefile.py

@@ -416,6 +416,56 @@ def test_reader_pathlike():
         assert len(sf) == 663
 
 
+def test_reader_dbf_only():
+    """
+    Assert that specifying just the
+    dbf argument to the shapefile reader
+    reads just the dbf file.
+    """
+    with shapefile.Reader(dbf="shapefiles/blockgroups.dbf") as sf:
+        assert len(sf) == 663
+        record = sf.record(3)
+        assert record[1:3] == ['060750601001', 4715]
+
+
+def test_reader_shp_shx_only():
+    """
+    Assert that specifying just the
+    shp and shx argument to the shapefile reader
+    reads just the shp and shx file.
+    """
+    with shapefile.Reader(shp="shapefiles/blockgroups.shp", shx="shapefiles/blockgroups.shx") as sf:
+        assert len(sf) == 663
+        shape = sf.shape(3)
+        assert len(shape.points) is 173
+
+    
+def test_reader_shp_dbf_only():
+    """
+    Assert that specifying just the
+    shp and shx argument to the shapefile reader
+    reads just the shp and dbf file.
+    """
+    with shapefile.Reader(shp="shapefiles/blockgroups.shp", dbf="shapefiles/blockgroups.dbf") as sf:
+        assert len(sf) == 663
+        shape = sf.shape(3)
+        assert len(shape.points) is 173
+        record = sf.record(3)
+        assert record[1:3] == ['060750601001', 4715]
+
+
+def test_reader_shp_only():
+    """
+    Assert that specifying just the
+    shp argument to the shapefile reader
+    reads just the shp file (shx optional).
+    """
+    with shapefile.Reader(shp="shapefiles/blockgroups.shp") as sf:
+        assert len(sf) == 663
+        shape = sf.shape(3)
+        assert len(shape.points) is 173
+
+
 def test_reader_filelike_dbf_only():
     """
     Assert that specifying just the
@@ -440,7 +490,21 @@ def test_reader_filelike_shp_shx_only():
         assert len(shape.points) is 173
 
 
-def test_reader_filelike_shx_optional():
+def test_reader_filelike_shp_dbf_only():
+    """
+    Assert that specifying just the
+    shp and shx argument to the shapefile reader
+    reads just the shp and dbf file.
+    """
+    with shapefile.Reader(shp=open("shapefiles/blockgroups.shp", "rb"), dbf=open("shapefiles/blockgroups.dbf", "rb")) as sf:
+        assert len(sf) == 663
+        shape = sf.shape(3)
+        assert len(shape.points) is 173
+        record = sf.record(3)
+        assert record[1:3] == ['060750601001', 4715]
+
+
+def test_reader_filelike_shp_only():
     """
     Assert that specifying just the
     shp argument to the shapefile reader