extract basename and remove extension with os.path.basename and os.pa…

…th.splitext.

wfdb/io/convert/csv.py

@@ -325,16 +325,14 @@ def csv_to_wfdb(
                 print("Signal names: {}".format(sig_name))
 
     # Determine the output directory
+    base_name = os.path.splitext(os.path.basename(file_name))[0]
+
     if write_dir:
         if not os.path.exists(write_dir):
             os.makedirs(write_dir)
-        output_base = os.path.join(
-            write_dir, os.path.basename(file_name).replace(".csv", "")
-        )
+        output_base = os.path.join(write_dir, base_name)
     else:
-        if os.sep in file_name:
-            file_name = file_name.split(os.sep)[-1]
-        output_base = file_name.replace(".csv", "")
+        output_base = base_name
 
     if verbose:
         print("Output base: {}".format(output_base))