It is my first attempt to use pyparsing and I'd like to ask how to filter this sample line:
survey = '''GPS,PN1,LA52.125133215643,LN21.031048525561,EL116.898812'''
to get output like: 1,52.125133215643,21.031048525561,116.898812
In general I have problem with understanding pyparsing logic so any help with this example will be appreciated. Thanks
Answer
You could start with something like this:
from pyparsing import *
survey = '''GPS,PN1,LA52.125133215643,LN21.031048525561,EL116.898812'''
number = Word(nums+'.').setParseAction(lambda t: float(t[0]))
separator = Suppress(',')
latitude = Suppress('LA') + number
longitude = Suppress('LN') + number
elevation = Suppress('EL') + number
line = (Suppress('GPS,PN1,')
+ latitude
+ separator
+ longitude
+ separator
+ elevation)
print line.parseString(survey)
The output of the script is:
[52.125133215643, 21.031048525561, 116.898812]
Edit: You might also want to consider lepl, which is a similar library that's pretty nicely documented. The equivalent script to the one above is:
from lepl import *
survey = '''GPS,PN1,LA52.125133215643,LN21.031048525561,EL116.898812'''
number = Real() >> float
with Separator(~Literal(',')):
latitude = ~Literal('LA') + number
longitude = ~Literal('LN') + number
elevation = ~Literal('EL') + number
line = (~Literal('GPS')
& ~Literal('PN1')
& latitude
& longitude
& elevation)
print line.parse(survey)