lattice definition with line syntax raises an error

[Landau1908]

Hi, Thomas

When I run my sequence under cpymad, a KeyError occurs as follows:

elements = madx.sequences['MYRING'].elements
Traceback (most recent call last):

  File "<ipython-input-45-c1560b76e813>", line 1, in <module>
    elements = madx.sequences['MYRING'].elements

  File "C:\Python27\lib\site-packages\cpymad-0.10.6-py2.7-win32.egg\cpymad\madx.py", line 531, in __getitem__
    raise KeyError

My python code is below:

from cpymad.madx import Madx
madx = Madx(command_log="HIMM_log.madx")
print(madx.version) 
madx.command.call(file="HIMM.txt")
twiss = madx.twiss(sequence='MYRING',columns=['s','x','y','betx','bety','Dx','Dy'])
elements = madx.sequences['MYRING'].elements

My sequence definition is below:

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

  CELL1:Line=(D11,Q11,D12,HB11,D13,PU11,D14,CY11,D15,
              SR11,D16,Q12,D17,CX11,D18,SH11,D16,Q13,
              D12,HB12,D19,PU12,D1a);

  CELL2:Line=(CY22,D21,SV21,D22,HB22,D23,Q23,D24,SR21,
              D25,Q22,D26,C21,D27,PU21,D28,HB21,D23,
              Q21,D29);

  CELL3:Line=(D31,PU31,D32,CX31,D33,Q31,D34,HB31,D35,
              PU32,D32,CY31,D36,SR31,D37,Q32,D3c,CX32,D3b,SH31,
              D37,Q33,D34,HB32,D39,CY32,D3a,PU33);

  CELL4:Line=(D41,SV41,D42,HB42,D43,Q43,D44,SR41,D4b,CX42,D4c,
              Q42,D46,CY41,D47,PU42,D48,HB41,D43,Q41,
              D44,S41,D49,CX41,D49,PU41,D4a);

  MYRING: Line=(CELL1,CELL2,CELL3,CELL4);

  BEAM, particle = proton, energy = 150;

  USE SEQUENCE = MYRING;

!--------------------------------------------------------------------

However, when I run a sequence with sequence syntax definition not a line definition, no KeyError occurs. I think if the line definition is the source of this error.

[coldfix]

Hey, try print(list(madx.sequences.keys())) to get a list of available sequence names. My guess is that the sequence name is converted to lower case by MAD-X (which is generally the case for pretty much everything that isn't quoted).

In general, you should only use lower-case names / columns / etc from inside cpymad.

[coldfix]

Also note that there is a syntax error in your sequence definition: you forgot the comma after USE.

[Landau1908]

Yes, lower case works well.

Your analysis is very accuracy. Thanks a lot.