Syntax error in string (invalid escape `\$`)

[kyrsjo]

In the elegant wrapper where it calls csv2sdds, there is a warning about a bad escape sequence in a string.

Relevant code fragment:

    # convert CSV to SDDS (ascii for now)
    subprocess.call(CONFIG.elegant_exec + 'csv2sdds ' + tmpfile + ' ' + filename + 
                        ' -asciiOutput -columnData=name=x,type=double,units=m' +
                        ' -columnData=name=xp,type=double' + 
                        ' -columnData=name=y,type=double,units=m' + 
                        ' -columnData=name=yp,type=double' + 
                        ' -columnData=name=t,type=double,units=s' + 
                        ' -columnData=name=p,type=double,units=\"m\$be\$nc\"' +
                        ' -columnData=name=dt,type=double,units=s' +
                        ' -columnData=name=particleID,type=ulong64', shell=True)

Link to the relevant line:

ABEL/abel/wrappers/elegant/elegant_wrapper.py

Line 214 in 7f8ecce

' -columnData=name=p,type=double,units=\"m\$be\$nc\"' +

Warning:

abel/wrappers/elegant/elegant_wrapper.py:214
  /home/kyrsjo/code/ABEL/abel/wrappers/elegant/elegant_wrapper.py:214: SyntaxWarning: invalid escape sequence '\$'

I don't know if you want to output "$" or "$" so I haven't made a PR, however if the wanted output is "$" then using either a raw string or escaping the backslash as in \\$ should work; if the wanted output is $ then no escape should be needed.

Also note that when using single-quote strings, you shouldn't need to escape double quotes.

To avoid needing escapes, consider using raw strings when appropriate.