[mkgmap-dev] How to display U. S. highway shields with numbers only

Sun Jan 4 05:33:42 GMT 2015

Gerd,

Thanks for the followup.  Somehow I overlooked the Substitution filter that
you suggest, which seems like a good idea.  It looks like your idea also
involves an Oracle Regex expression, with which I am not familiar.  I
thought about that, but the URL in the Conversion Style Manual for the Regex
documentation is no longer correct.  (Can someone on this mailing list see
that it is corrected?)  After a little searching on the Java website, I did
not find the documentation, and did not want to take a lot of time looking,
so I tried a different tack.  After much thought, I came up with a series of
commands that seems to produce the desired output.  However, it looks like
the idea of using the Substitution filter might produce a more elegant
solution.  I will probably look into that.

Anyway, here is the sequence of commands I came up with that seemed to work.
(I live in Indiana.)  I have only included the commands that pertain to U.
S. and state highways.  The motorways (interstates) were more
straightforward and a lot easier, because their ref values are much more
consistent.  The problem I had to overcome with the other highways is that
the number of characters in the ref key value can vary, from none, to one or
more.

# Append extra characters to the end of the ref value to ensure it is more
than one character in length, otherwise an error will be returned by the
Substring filter later.

# ("AB" are dummy characters.)

highway = * & ref = * { set ref = '$(ref) AB' }

# Create the letter_ref key that will determine later what type of symbol to
display on the highway.

highway = * & ref = * { set letter_ref = '$(ref|substring:0:2)' }

# Extract the numbers only from the ref value, which will become the numbers
inside the symbols.

highway = * & ref = * { set number_ref = '$(ref|part:" :-2)' }

#If the highway is a U. S. highway, use a shield symbol.

letter_ref = 'US' {name '${number_ref|highway-symbol:shield:3} ${name}' |
'${number_ref|highway-symbol:shield:3}' | '${name}'; addlabel '${name}
(${ref})' }

# If the highway is a state highway, use a round symbol.

letter_ref = 'SR' | letter_ref = 'IN' {name
'${number_ref|highway-symbol:round:3} ${name}' |
'${number_ref|highway-symbol:round:3}' | '${name}'; addlabel '${name}
(${ref})' }

_____________________________________________

Hi Mark,

okay, so your problem is not directly related to the highway symbols.

What you need is a simple filter to return the part of a string which starts
at the first digit. I guess this can be done with subst plus a regular
expression, but I'm not sure how exactly.

Something like

ref=* {set my_ref = ${ref|subst:"[a-zA-Z]*~>"}

Gerd

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