[Tutor] changing string in place

[Martin Walsh]

Jon Crump wrote:
> Dear all,
> 
> I've been around and around with this and can't seem to conceptualize it
> properly.
> 
> I've got a javascript object in a text file that I'd like to treat as
> json so that I can import it into a python program via
> simplejson.loads(); however, it's not proper json because it has new
> Date() object declarations in it. So I thought to pre-process it by
> translating the dates into ISO format, but RE is making me cross-eyed.
> 
> example string:
> 
> s = """{"title" : "Hebertot, Normandie", "start" : new Date(1203,10,7),
> "description" : "Hardy's long name: Hebertot, Normandie. <br>
> <img src=\"document.png\" style=\"cursor: pointer\"
> onclick=\"SimileAjax.WindowManager.cancelPopups();show_next('tab3');pager('035');
> return false\"/>pg.035: 1203-10-10 to 1203-11-18"},{"title" :
> "Newark-Upon-Trent, Nottinghamshire", "start" : new Date(1216,9,16),
> "end" : new Date(1216,9,18), "description" : "Hardy's long name:
> Newark-Upon-Trent, Nottinghamshire. <br> "}"""
> 
> I can locate the dates with:
> jdate = re.compile('new Date\(\d{4},\d{1,2},\d{1,2}\)')

I think you're pretty close...

# note the extra parens
jdate = re.compile('new Date\((\d{4}),(\d{1,2}),(\d{1,2})\)')

... then ...

print jdate.sub(r'"\1-\2-\3"', s)

{"title" : "Hebertot, Normandie", "start" : "1203-10-7", "description" :
"Hardy's long name: Hebertot, Normandie. <br> <img
src="document.png" style="cursor: pointer"
onclick="SimileAjax.WindowManager.cancelPopups();show_next('tab3');pager('035');
return false"/>pg.035: 1203-10-10 to 1203-11-18"},{"title" :
"Newark-Upon-Trent, Nottinghamshire", "start" : "1216-9-16", "end" :
"1216-9-18", "description" : "Hardy's long name: Newark-Upon-Trent,
Nottinghamshire. <br> "}

You can also use named groups which *might* help make clearer what's
happening above, something like:

jdate = re.compile('new
Date\((?P<Year>\d{4}),(?P<Month>\d{1,2}),(?P<Day>\d{1,2})\)')

print jdate.sub(r'"\g<Year>-\g<Month>-\g<Day>"', s)

More info here:
http://docs.python.org/library/re.html#re.sub


HTH,
Marty