How to obtain BPM readings?

[Landau1908]

Hi, Thomas

How to get the BPM readings? I write a small code, but it can't work anyway.

from cpymad.madx import Madx
madx = Madx(command_log="HIMM_log.madx")
madx.command.call(file="HIMM_cpymad")
madx.command.twiss(sequence="himm")
twiss0 = madx.get_table("twiss")
#use madx builtin function `table` to get BPM readings
bpm1 = madx.command.table('twiss','bpm12','x')

[coldfix]

There is no MAD-X command called TABLE, so your code is clearly incorrect. Also, it looks like you might be passing an incorrect file name. Furthermore, you did (again) not deliver the MAD-X example file with your issue. What are you trying to achieve exactly? BTW: I'm not a MAD-X expert, so if you're asking for some basic MAD-X functionality, ask them.

[Landau1908]

Thanks, Thomas
I want to simulate orbit correct, and the BPM readings are essential for calculating Orbit Response Matrix (ORM). Recently, I write a code to obtain the BPM readings, and I think it is very verbose using this way to obtain the BPM readings, although it works well. Is there any elegant method to get the BPM readings? Below is my code and the Madx file used.

from __future__ import division
import matplotlib.pylab as plt
from cpymad.madx import Madx
def readBpm(bpm, sequence="himm"):
    """
    read the x value of BPM 
    """
    madx.command.twiss(sequence=sequence)
    twiss = madx.get_table("twiss")
    bpm = bpm
    ind = []
    for bpm0 in bpm:
        ind.append([i for i, bpm1 in enumerate(twiss['name']) if bpm1 == bpm0])
    #print ind
    s = []
    x = []
    for i0 in ind:
        s.append(twiss['s'][i0])
        x.append(twiss['x'][i0])
    return s, x
madx = Madx(command_log="HIMM_log.madx") 
madx.command.call(file="HIMM_cpymad")
madx.command.twiss(sequence="himm")
#plot bpm data before correct
bpm = ['bpm11:1','bpm12:1','bpm21:1','bpm31:1','bpm32:1','bpm33:1','bpm42:1','bpm41:1']
sequence = "himm"
bpmData = readBpm(bpm, sequence)
s = bpmData[0]
x = bpmData[1]
plt.plot(s,x,'b-o',label="befor correct")
plt.legend()
plt.show()

Max file, named as "HIMM_cpymad".

TITLE,'HIMM Project';
  OPTION, INFO, -ECHO,WARN;
 BEAM, particle = carbon, energy = 0.007;

! Defining elements

! drift--------------------------------------------------------------

  D11:drift,l=1.75;
  D12:drift,l=0.40;
  D13:drift,l=0.25;
  D14:drift,l=0.10;
  D15:drift,l=0.13;
  D16:drift,l=0.15;
  D17:drift,l=1.775;
  D18:drift,l=0.125;
  D19:drift,l=0.25;
  D1a:drift,l=0.53;

  D21:drift,l=0.43;
  D22:drift,l=0.35;
  D23:drift,l=0.40;
  D24:drift,l=0.15;
  D25:drift,l=2.00;
  D26:drift,l=0.44;
  D27:drift,l=0.10;
  D28:drift,l=0.24;
  D29:drift,l=1.75;

  D31:drift,l=0.67;
  D32:drift,l=0.10;
  D33:drift,l=0.63;
  D34:drift,l=0.40;
  D35:drift,l=0.25;
  D36:drift,l=0.13;
  D37:drift,l=0.15;
  !D38:drift,l=2.00;
  D39:drift,l=0.45;
  D3a:drift,l=0.33;
 D3b:drift,l=0.125;
 D3c:drift,l=1.775;

  D41:drift,l=0.43;
  D42:drift,l=0.35;
  D43:drift,l=0.40;
  D44:drift,l=0.15;
  !D45:drift,l=2.00;
  D46:drift,l=0.455;
  D47:drift,l=0.075;
  D48:drift,l=0.25;
  D491:drift,l=0.06;
  D492:drift,l=0.07;
  D4a:drift,l=0.81;
 D4b:drift,l=0.73;
 D4c:drift,l=1.17;
! marker-------------------------------------------------------------

  m1:marker;
  m2:marker;

! constant definition of dipoles-------------------------------------

  N=8;
  !bero=6.342738
  !Bm=1.58568
  ro = 4.0; !bero/Bm
  leng := ro*(twopi/N);

  Rr=0.07; !Reference radius of field measurement
  a1=0; !quadrupole component in dipoles
  a2=0.0; !end field
  a3=0.0; !end field

! dipole without multipole-------------------------------------------

  RB: SBEND, L=leng,ANGLE=TWOPI/N,K0=1/ro,K1=a1*(1/ro)*(1/Rr),
             E1=PI/8,E2=PI/8,FINT=0.55,FINTX=0.55,HGAP=0.037;
  !EB: RBEND, ANGLE=a2*TWOPI/N;
  !EA: RBEND, ANGLE=a3*TWOPI/N;

! dipole definition--------------------------------------------------

   B11:RB;
   B12:RB;
   B21:RB;
   B22:RB;
   B31:RB;
   B32:RB;
   B41:RB;
   B42:RB;

   HB11: LINE=(B11);
   HB12: LINE=(B12);

   HB21: LINE=(B21);
   HB22: LINE=(B22);

   HB31: LINE=(B31);
   HB32: LINE=(B32);

   HB41: LINE=(B41);
   HB42: LINE=(B42);

! quadrupole without multipole---------------------------------------

  QF: QUADRUPOLE, L=0.2, K1=0.799839688766;
  QD: QUADRUPOLE, L=0.2, K1=-1.00783349327;
  QFF: QUADRUPOLE, L=0.35, K1=1.038161630875;
  !FQ: QUADRUPOLE, L=0.15,K1=0.00;

! quadrupole definition----------------------------------------------

  Q11:QF;
  Q12:QD;
  Q13:QFF;

  Q21:QF;
  Q22:QD;
  Q23:QFF;

  Q31:QF;
  Q32:QD;
  Q33:QFF;

  Q41:QF;
  Q42:QD;
  Q43:QFF;

  !FQ41: FQ;

! chromaticity sextupole definition----------------------------------

  SEXTCH:  sextupole,l=0.15, k2=0.0;
  SEXTCV:  sextupole,l=0.15, k2=0.0;

  SH11: SEXTCH;
  SH31: SEXTCH;
  SV21: SEXTCV;
  SV41: SEXTCV;

! resonance sextupole definition-------------------------------------

  SEXTR:  sextupole,l=0.15, k2=0.0;

  SR11: SEXTR;
  SR21: SEXTR;
  SR31: SEXTR;
  SR41: SEXTR;
  S41: SEXTR;

! corrector Kicker---------------------------------------------------

  CYX: KICKER, L=0.1, HKICK:=0.0, VKICK:=0.0;
  CY: VKICKER, L=0.1, KICK:=0.0;
  CX: HKICKER, L=0.1, KICK:=0.0;
  CX1:CX, KICK=0.004543802;
  CX2:CX, KICK=-0.001323422;
  CX3:CX, KICK=0.001031226;
  CX4:CX, KICK=0.000204781;
  CX5:CX, KICK=0.006345063;
  CX6:CX, KICK=-0.000924923;
  CY11:CY;
  CY22:CY;
  CY31:CY;
  CY32:CY;
  CY41:CY;
  CY42:CY;
  C21:CYX;


! MONITOR------------------------------------------------------------

  PKUP: MONITOR, L=0.25;

  BPM11: PKUP;
  BPM12: PKUP;

  BPM21: PKUP;

  BPM31: PKUP;
  BPM32: PKUP;
  BPM33: PKUP;

  BPM41: PKUP;
  BPM42: PKUP;

  PU11: LINE=(BPM11);
  PU12: LINE=(BPM12);

  PU21: LINE=(BPM21);

  PU31: LINE=(BPM31);
  PU32: LINE=(BPM32);
  PU33: LINE=(BPM33);

  PU41: LINE=(BPM41);
  PU42: LINE=(BPM42);

! ring definition----------------------------------------------------

  CELL1:Line=(D11,Q11,D12,HB11,D13,PU11,D14,CY11,D15,
              SR11,D16,Q12,D17,CX1,D18,SH11,D16,Q13,
              D12,HB12,D19,PU12,D1a);

  CELL2:Line=(CY22,D21,SV21,D22,HB22,D23,Q23,D24,SR21,
              D25,Q22,D26,CX2,D27,PU21,D28,HB21,D23,
              Q21,D29);

  CELL3:Line=(D31,PU31,D32,CX3,D33,Q31,D34,HB31,D35,
              PU32,D32,CY31,D36,SR31,D37,Q32,D3c,CX4,D3b,SH31,
              D37,Q33,D34,HB32,D39,CY32,D3a,PU33);

  CELL4:Line=(D41,SV41,D42,HB42,D43,Q43,D44,SR41,D4b,CX6,D4c,
              Q42,D46,CY42,D47,PU42,D48,HB41,D43,Q41,
              D44,S41,D491,CX5,D492,CY41,D491,PU41,D4a);

  himm: Line=(CELL1,CELL2,CELL3,CELL4);
 USE, SEQUENCE = himm;
//--------------error definition of dipole-------------

//EOPT,seed = 912345678

SELECT, FLAG = ERROR, CLEAR;
SELECT, FLAG=ERROR, CLASS=B11;
EFCOMP, ORDER=0, RADIUS=0.5,
DKN = {1E-2,0,0},
DKS = {0,0,0};

[coldfix]

I'm not your personal advisor. And yes, this can be written much shorter - with just some knowledge in python programming. It has nothing to do with cpymad.