feat+refactor: add astype function

crackle/__init__.py

@@ -48,6 +48,7 @@
 	header, contains, crack_codes, num_labels,
 )
 from .operations import (
+	astype,
 	remap, refit, renumber,
 	min, max, 
 	zstack, zsplit, 

crackle/array.py

@@ -8,6 +8,7 @@
   components,
 )
 from .operations import (
+  astype,
   refit, 
   renumber,
   zstack, zsplit,
@@ -70,9 +71,12 @@ def max(self):
   def remap(self, buf, mapping, preserve_missing_labels=False):
     return CrackleArray(remap(buf, mapping, preserve_missing_labels))
 
-  def refit(self) -> bytes:
+  def refit(self):
     return CrackleArray(refit(self.binary))
 
+  def astype(self, dtype):
+    return CrackleArray(astype(self.binary, dtype))
+
   def renumber(self, start:int = 0) -> bytes:
     return CrackleArray(renumber(self.binary, start))
 

crackle/operations.py

@@ -110,20 +110,29 @@ def remap(binary:bytes, mapping:dict, preserve_missing_labels:bool = False):
   binary[offset:offset+uniq_bytes] = list(all_labels.view(np.uint8))
   return bytes(binary)
 
-def refit(binary:bytes) -> bytes:
+def astype(binary:bytes, dtype) -> bytes:
   """
   Change the rendered dtype to the smallest
   dtype needed to render the image without
   loss of precision.
   """
   head = header(binary)
-  dtype = fastremap.fit_dtype(head.dtype, max(binary))
   head.data_width = np.dtype(dtype).itemsize
   return b''.join([ 
     head.tobytes(), 
     binary[CrackleHeader.HEADER_BYTES:] 
   ])
 
+def refit(binary:bytes) -> bytes:
+  """
+  Change the rendered dtype to the smallest
+  dtype needed to render the image without
+  loss of precision.
+  """
+  head = header(binary)
+  dtype = fastremap.fit_dtype(head.dtype, max(binary))
+  return astype(binary, dtype)
+
 def renumber(binary:bytes, start=0) -> Tuple[bytes, dict]:
   """
   Renumber the array and resize the data type