feat: control output file name for charge analysis

Author: c-dilks

qa-physics/charge_analysis/README.md

@@ -2,9 +2,17 @@
 
 From Bhawani Singh
 
+`./analyze.py` Produces PNG files comparing the DAQ-gated FC charge determined from
+- the `RUN::scaler` bank directly
+- the livetime and ungated charge, by multiplication
+
+### Example
+
+Suppose we have reheated (`qtl reheat`) a skim file on `/cache` and
+stored it at `/volatile/reheat/`. To compare results:
+
 ```bash
-./analyze HIPO_FILE
+./analyze.py /cache/...../skim.hipo before_reheat
+./analyze.py /volatile/reheat/skim.hipo after_reheat
+ls -t *.png
 ```
-Produces PNG files comparing the DAQ-gated FC charge determined from
-- directly from the `RUN::scaler` bank
-- from the livetime and ungated charge, by multiplication

qa-physics/charge_analysis/analyze.py

@@ -22,8 +22,14 @@
 
 def main():
 
-    if len(sys.argv) != 2:
-        print(f'USAGE: {sys.argv[0]} [HIPO_FILE]')
+    if len(sys.argv) != 3:
+        print(f'''
+USAGE: {sys.argv[0]} [INPUT_HIPO_FILE] [OUTPUT_FILE_SUFFIX]
+    INPUT_HIPO_FILE       input HIPO file
+    OUTPUT_FILE_SUFFIX    append this string to the output
+                          file name; useful if you are comparing
+                          output files before and after reheating
+        ''')
         exit(2)
     hipo_file = sys.argv[1]