Fix: MAD-X Variable Name Length Limit (#102)

pylhc/__init__.py

@@ -10,7 +10,7 @@
 __title__ = "pylhc"
 __description__ = "An accelerator physics script collection for the OMC team at CERN."
 __url__ = "https://github.com/pylhc/pylhc"
-__version__ = "0.7.1"
+__version__ = "0.7.2"
 __author__ = "pylhc"
 __author_email__ = "[email protected]"
 __license__ = "MIT"

pylhc/lsa_to_madx.py

@@ -33,6 +33,17 @@
 
 Two files, **LHCBEAM_MD_ATS_2022_05_04_B1_RigidWaitsShift_IP1pos_definition.tfs** and **LHCBEAM_MD_ATS_2022_05_04_B1_RigidWaitsShift_IP1pos_knob.madx** will be written to disk.
 
+.. warning::
+ In ``MAD-X``, variable names with 48 or more characters will cause an issue.
+ As a consequence, this script will automatically truncate the knob name if needed when created the trim variable name.
+ One should not be surprised if long ``LSA`` knob names appear slightly differently in the created ``MAD-X`` files, then functionality stays intact.
+
+ For instance, the knob ``LHCBEAM/MD_ATS_2022_05_04_B1_RigidWaitsShift_IP1pos`` will lead to the following trim variable definition:
+ 
+ .. code-block:: fortran
+
+ trim_D_ATS_2022_05_04_B1_RigidWaitsShift_IP1pos = 1.0;
+
 In order to reproduce a specific machine configuration at a given time, one can gather all knobs and their trim values for this configuration in a text file and feed this file to the script.
 In this file, each line should hold a knob name as it appears in LSA and its trim value.
 Lines starting with a ``#`` character will be ignored.
@@ -143,8 +154,7 @@ def get_madx_script_from_definition_dataframe(deltas_df: tfs.TfsDataFrame, lsa_k
  change_commands = [f"! Start of change commands for knob: {lsa_knob}"]
 
  # Set this to 1 by default but can be changed by the user to reproduce a given trim
- knob_itself = lsa_knob.split("/")[-1] # without the LHCBEAM[12]?/ part
- trim_variable = f"{knob_itself}_trim"
+ trim_variable = _get_trim_variable(lsa_knob)
  change_commands.append("! Change this value to reproduce a different trim")
  change_commands.append(f"! Beware some knobs are not so linear in their trims")
  change_commands.append(f"{trim_variable} = {trim};")
@@ -157,6 +167,26 @@ def get_madx_script_from_definition_dataframe(deltas_df: tfs.TfsDataFrame, lsa_k
  return "\n".join(change_commands)
 
 
+def _get_trim_variable(lsa_knob: str) -> str:
+ """
+ Generates the ``MAD-X`` trim variable name from an ``LSA`` knob.
+ Handles the variable name character limit of ``MAD-X``.
+ """
+ knob_itself = lsa_knob.split("/")[-1] # without the LHCBEAM[12]?/ part
+
+ # MAD-X will crash if the variable name is >48 characters or longer! It will also silently fail
+ # if the variable name starts with an underscore or a digit. Adding "trim_" at the start circumvents
+ # the latter two, and we make sure to truncate the knob so that the result is <=47 characters
+ if len(knob_itself) > 42:
+ LOG.info(f"Knob '{knob_itself}' is too long to be a MAD-X variable and will be truncated.")
+ knob_itself = knob_itself[-42:]
+ LOG.debug(f"Truncated knob name to '{knob_itself}'.")
+
+ trim_variable = f"trim_{knob_itself.lstrip('_')}"
+
+ return trim_variable
+
+
 # ----- Script Part ----- #
 
 

tests/inputs/lsa_to_madx/LHCBEAM_MD_ATS_2022_05_04_B1_RigidWaitsShift_IP1pos_knob.madx

@@ -1,20 +1,20 @@
-! Start of change commands for knob: LHCBEAM/MD_ATS_2022_05_04_B1_RigidWaitsShift_IP1pos
+! Start of change commands for knob: LHCBEAM/ATS_Test_Knob
 ! Change this value to reproduce a different trim
 ! Beware some knobs are not so linear in their trims
-MD_ATS_2022_05_04_B1_RigidWaitsShift_IP1pos_trim = 1.0;
+trim_ATS_Test_Knob = 1.0;
 ! Impacted variables
-kq9.r1b1 = kq9.r1b1 + ( 0.000139519135701 ) * MD_ATS_2022_05_04_B1_RigidWaitsShift_IP1pos_trim;
-kq5.r1b1 = kq5.r1b1 + ( -0.000208665238461 ) * MD_ATS_2022_05_04_B1_RigidWaitsShift_IP1pos_trim;
-kq7.l1b1 = kq7.l1b1 + ( -1.65434776136e-05 ) * MD_ATS_2022_05_04_B1_RigidWaitsShift_IP1pos_trim;
-kq8.r1b1 = kq8.r1b1 + ( -5.16630898346e-05 ) * MD_ATS_2022_05_04_B1_RigidWaitsShift_IP1pos_trim;
-kq8.l1b1 = kq8.l1b1 + ( 4.70197155664e-05 ) * MD_ATS_2022_05_04_B1_RigidWaitsShift_IP1pos_trim;
-kq10.r1b1 = kq10.r1b1 + ( -1.96085402422e-05 ) * MD_ATS_2022_05_04_B1_RigidWaitsShift_IP1pos_trim;
-kq4.l1b1 = kq4.l1b1 + ( 7.35134890419e-05 ) * MD_ATS_2022_05_04_B1_RigidWaitsShift_IP1pos_trim;
-kq4.r1b1 = kq4.r1b1 + ( 4.70408231195e-05 ) * MD_ATS_2022_05_04_B1_RigidWaitsShift_IP1pos_trim;
-kq10.l1b1 = kq10.l1b1 + ( -2.47050375037e-05 ) * MD_ATS_2022_05_04_B1_RigidWaitsShift_IP1pos_trim;
-kq7.r1b1 = kq7.r1b1 + ( -2.3806014724e-05 ) * MD_ATS_2022_05_04_B1_RigidWaitsShift_IP1pos_trim;
-kq9.l1b1 = kq9.l1b1 + ( 0.000118330906844 ) * MD_ATS_2022_05_04_B1_RigidWaitsShift_IP1pos_trim;
-kq5.l1b1 = kq5.l1b1 + ( -0.000214221465285 ) * MD_ATS_2022_05_04_B1_RigidWaitsShift_IP1pos_trim;
-kq6.r1b1 = kq6.r1b1 + ( 0.000218127839616 ) * MD_ATS_2022_05_04_B1_RigidWaitsShift_IP1pos_trim;
-kq6.l1b1 = kq6.l1b1 + ( 0.000125226986711 ) * MD_ATS_2022_05_04_B1_RigidWaitsShift_IP1pos_trim;
-! End of change commands for knob: LHCBEAM/MD_ATS_2022_05_04_B1_RigidWaitsShift_IP1pos
+kq9.r1b1 = kq9.r1b1 + ( 0.000139519135701 ) * trim_ATS_Test_Knob;
+kq5.r1b1 = kq5.r1b1 + ( -0.000208665238461 ) * trim_ATS_Test_Knob;
+kq7.l1b1 = kq7.l1b1 + ( -1.65434776136e-05 ) * trim_ATS_Test_Knob;
+kq8.r1b1 = kq8.r1b1 + ( -5.16630898346e-05 ) * trim_ATS_Test_Knob;
+kq8.l1b1 = kq8.l1b1 + ( 4.70197155664e-05 ) * trim_ATS_Test_Knob;
+kq10.r1b1 = kq10.r1b1 + ( -1.96085402422e-05 ) * trim_ATS_Test_Knob;
+kq4.l1b1 = kq4.l1b1 + ( 7.35134890419e-05 ) * trim_ATS_Test_Knob;
+kq4.r1b1 = kq4.r1b1 + ( 4.70408231195e-05 ) * trim_ATS_Test_Knob;
+kq10.l1b1 = kq10.l1b1 + ( -2.47050375037e-05 ) * trim_ATS_Test_Knob;
+kq7.r1b1 = kq7.r1b1 + ( -2.3806014724e-05 ) * trim_ATS_Test_Knob;
+kq9.l1b1 = kq9.l1b1 + ( 0.000118330906844 ) * trim_ATS_Test_Knob;
+kq5.l1b1 = kq5.l1b1 + ( -0.000214221465285 ) * trim_ATS_Test_Knob;
+kq6.r1b1 = kq6.r1b1 + ( 0.000218127839616 ) * trim_ATS_Test_Knob;
+kq6.l1b1 = kq6.l1b1 + ( 0.000125226986711 ) * trim_ATS_Test_Knob;
+! End of change commands for knob: LHCBEAM/ATS_Test_Knob

tests/inputs/lsa_to_madx/MD_ATS_2022_05_04_B1_RigidWaitsShift_IP1pos.tfs

@@ -1,4 +1,4 @@
-@ Knob %s "LHCBEAM/MD_ATS_2022_05_04_B1_RigidWaitsShift_IP1pos"
+@ Knob %s "LHCBEAM/ATS_Test_Knob"
 @ Optics %s "R2022a_A30cmC30cmA10mL200cm"
 @ Info %s "In MAD-X it should be 'name = name + DELTA * knobValue'"
 * INDEX&&& CIRCUIT DELTA_K

tests/inputs/lsa_to_madx/knobs_definitions.txt

@@ -1,3 +1,4 @@
+# For optics R2017aT_A30C30A10mL300_CTPPS2
 #Nonlinear
 LHCBEAM/2017_IRNL_IR1a4 0.5
 LHCBEAM/2017_IRNL_IR1b3_couplFD 1.0

tests/unit/test_lsa_to_madx.py

@@ -10,6 +10,7 @@
 from pandas._testing import assert_dict_equal
 
 from pylhc.lsa_to_madx import (
+ _get_trim_variable,
  get_madx_script_from_definition_dataframe,
  parse_knobs_and_trim_values_from_file,
 )
@@ -26,10 +27,18 @@ def test_parse_knob_definition_file(self, knobs_file, parsed_definitions):
 
 class TestMADXWriting:
  def test_madx_script_writing_from_definition_df(self, knob_definition_df, correct_madx_script):
- script = get_madx_script_from_definition_dataframe(
- knob_definition_df, lsa_knob="LHCBEAM/MD_ATS_2022_05_04_B1_RigidWaitsShift_IP1pos"
+ script = get_madx_script_from_definition_dataframe(knob_definition_df, lsa_knob="LHCBEAM/ATS_Test_Knob")
+ assert script == correct_madx_script
+
+ @pytest.mark.parametrize("lsa_knob", ["LHCBEAM/Super_Duper_Long_Name_For_A_Knob_Will_Be_Truncated_For_Sure", "ATS_Test_Knob"])
+ def test_trim_variable_from_long_knob_name(self, lsa_knob):
+ """Testing that the generated trim variable is correctly truncated if too long."""
+ assert (
+ _get_trim_variable("ATS_2022_05_08_B1_arc_by_arc_coupling_133cm_30cm")
+ == "trim_22_05_08_B1_arc_by_arc_coupling_133cm_30cm"
  )
- assert script == correct_madx_script # TODO: figure why this doesn't work?
+ assert _get_trim_variable("___knob") == "trim_knob" # make sure we handle several underscores
+ assert len(_get_trim_variable(lsa_knob)) < 48
 
 
 # ----- Fixtures ----- #