diff --git a/reduction_tools/custom_spliting.py b/reduction_tools/custom_spliting.py
new file mode 100755
index 0000000..263e0b0
--- /dev/null
+++ b/reduction_tools/custom_spliting.py
@@ -0,0 +1,54 @@
+import argparse
+import re
+
+def extract_data_from_chunks( input_file, output_file, name ):
+
+    print( "reading input file" )
+    with open(input_file, 'r') as file:
+        data = file.read()
+    print( "done" )
+
+    print( "finding chunks" )
+    chunks = re.findall(r'----- Begin chunk -----.*?----- End chunk -----', data, re.DOTALL)
+    print( "done. {0} found".format( len( chunks ) ) )
+
+    print( "cycle through chunks" )
+    with open(output_file, 'w') as out_file:
+        for chunk in chunks:
+            indexed_by_line = re.search(r'indexed_by = (.+)', chunk)
+            if indexed_by_line:
+                indexed_by_value = indexed_by_line.group(1).strip()
+                if indexed_by_value != 'none':
+                    image_filename_match = re.search(r'Image filename: (.+\.h5)', chunk)
+                    event_match = re.search(r'Event: (//\d+)', chunk)
+#                    condition_match = re.search(r'run\d+-(?:aslov2rac1|aslov2-Rac1)_([\w\d]+_SOS)', chunk)
+
+                    if image_filename_match and event_match:
+                        image_filename = image_filename_match.group(1)
+                        event_number = event_match.group(1)
+                        #condition = condition_match.group(1)  # Extracts "100ns_0p8uJ_SOS" or "dark_SOS"
+
+                        out_file.write(f"{image_filename} {event_number} {name}\n")
+    print( "done" )
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser(description="Extract data from chunks in a text file.")
+    parser.add_argument(    "-i",
+                            "--input",
+                            help="Input file path",
+                            required=True
+                        )
+    parser.add_argument(    "-o",
+                            "--output",
+                            help="Output file path",
+                            required=True
+                        )
+    parser.add_argument(    "-n",
+                            "--name",
+                            help="name of dataset",
+                            required=True
+                        )
+    args = parser.parse_args()
+
+    extract_data_from_chunks( args.input, args.output, args.name )
+