MAINT: Minor touchups in npyio (#17796)

* Simplify logic for encoding kwarg in _decode_line.

* Remove unnecessary else branch from split_line.

* MAINT: rm else branch from loadtxt.

* MAINT: re-nest encoding parsing.

Co-Authored-By: mattip <matti.picus@gmail.com>

* condense return statement.

Co-authored-by: mattip <matti.picus@gmail.com>

numpy/lib/_iotools.py

@@ -18,6 +18,8 @@ def _decode_line(line, encoding=None):
     ----------
     line : str or bytes
          Line to be decoded.
+    encoding : str
+         Encoding used to decode `line`.
 
     Returns
     -------
@@ -27,9 +29,8 @@ def _decode_line(line, encoding=None):
     """
     if type(line) is bytes:
         if encoding is None:
-            line = line.decode('latin1')
-        else:
-            line = line.decode(encoding)
+            encoding = "latin1"
+        line = line.decode(encoding)
 
     return line
 

numpy/lib/npyio.py

@@ -965,10 +965,7 @@ def split_line(line):
         if comments is not None:
             line = regex_comments.split(line, maxsplit=1)[0]
         line = line.strip('\r\n')
-        if line:
-            return line.split(delimiter)
-        else:
-            return []
+        return line.split(delimiter) if line else []
 
     def read_data(chunk_size):
         """Parse each line, including the first.
@@ -1030,11 +1027,10 @@ def read_data(chunk_size):
 
     user_converters = converters
 
+    byte_converters = False
     if encoding == 'bytes':
         encoding = None
         byte_converters = True
-    else:
-        byte_converters = False
 
     if usecols is not None:
         # Allow usecols to be a single int or a sequence of ints