Add ShpReader and ShxReader

Add ShxReader

Add ShpReader

Can combine ._shape too if rec length yielded/cached (as well as pos)

Is it still necessary to support out of spec shapefiles, with next_shape_pos?

Cache iterator in ShpReader

Use a cached generator

Passes pytest, mypy and ruff check

Reformat and run hooks

Update test_shapefile.py

Swap out Nones in MBox part of header

Update shapefile.py

Add ISDATA_LOWER_BOUND =-1e38 to differentiate from NODATA = -1e39 (as per legacy)

Add zbox and mbox properties

Author: JamesParrott

README.md

@@ -93,7 +93,12 @@ part of your geospatial project.
 
 # Version Changes
 
-## 3.0.9
+## 3.0.9.dev
+### Bug fix
+ - 	Correct NODATA lower threshold to -1e38 (as per [spec](https://www.esri.com/content/dam/esrisites/sitecore-archive/Files/Pdfs/library/whitepapers/pdfs/shapefile.pdf) 2, Numeric Types). This is 10% of
+ PyShp's previous threshold -10e38, so it is possible large negative values x (-1e39 < x < -1e38 will now be NODATA.
+
+
 ### Security
  - Add python_version >= 3.10 to pre-commit dev & lint groups' 'dependency' (due to CVE in filelock 3.19).
 
@@ -514,7 +519,7 @@ and the bounding box area the shapefile covers:
 	>>> len(sf)
 	663
 	>>> sf.bbox
-	(-122.515048, 37.652916, -122.327622, 37.863433)
+	BBox(xmin=-122.515048, ymin=37.652916, xmax=-122.327622, ymax=37.863433)
 
 Finally, if you would prefer to work with the entire shapefile in a different
 format, you can convert all of it to a GeoJSON dictionary, although you may lose
@@ -1473,7 +1478,7 @@ Shapefiles containing M-values can be examined in several ways:
 	>>> r = shapefile.Reader('shapefiles/test/linem')
 
 	>>> r.mbox # the lower and upper bound of M-values in the shapefile
-	(0.0, 3.0)
+	MBox(mmin=0.0, mmax=3.0)
 
 	>>> r.shape(0).m # flat list of M-values
 	[0.0, None, 3.0, None, 0.0, None, None]
@@ -1506,7 +1511,7 @@ To examine a Z-type shapefile you can do:
 	>>> r = shapefile.Reader('shapefiles/test/linez')
 
 	>>> r.zbox # the lower and upper bound of Z-values in the shapefile
-	(0.0, 22.0)
+	ZBox(zmin=0.0, zmax=22.0)
 
 	>>> r.shape(0).z # flat list of Z-values
 	[18.0, 20.0, 22.0, 0.0, 0.0, 0.0, 0.0, 15.0, 13.0, 14.0]

changelog.txt

@@ -1,5 +1,10 @@
 VERSION 3.0.9.dev
 
+2026-05-23
+	Bug fix (BREAKING CHANGE):
+	* Correct NODATA lower threshold to -1e38 (as per [spec](https://www.esri.com/content/dam/esrisites/sitecore-archive/Files/Pdfs/library/whitepapers/pdfs/shapefile.pdf)
+	page 2, Numeric Types). This is a tenth of PyShp's previous threshold -10e38, but still a huge negative number.
+
 2026-05-20
 	Security:
 	* Add python_version >= 3.10 to pre-commit dev & lint groups' 'dependency' (due to CVE in filelock 3.19).