xml data handling regex find replace with conditional values - regex

Question

I got a xml file which looks like this
<DocumentElement>
<Table1>
<Date>2013-08-24</Date>
<Time>00:07:23</Time>
<Type>in</Type>
<Number>393483419761</Number>
<Name>Marc</Name>
<Message>Lorem ipsum</Message>
</Table1>
<Table1>
<Date>2013-08-24</Date>
<Time>00:09:09</Time>
<Type>out</Type>
<Number>1215468498561</Number>
<Name>Marc</Name>
<Message>Lorem ipsum</Message>
</Table1>
<DocumentElement>
What I want to do is Check the Date Value and if the Month is 01, add <Month>january</Month> after </Date>, and if month is 02 add <Month>february</Month> and so on.
So what I got so far is either:
<Date>(\d{4})-01-(\d{2})</Date>
<Date>$1-01-$2</Date>
<Month>january</Month>
or i'd like to do something like:
<Date>(\d{4})-(\d{2})-(\d{2})</Date>
if ($2 = 01) {
<Date>$1-$2-$3</Date>
<Month>january</Month>
}
elseif ($2 = 02) {
<Date>$1-$2-$3</Date>
<Month>february</Month>
}
whats the usual way to handle and manipulate data like this?

Answer 1

Normally if you are parsing XML you would use a real parser instead of regular expressions. But in your particular case it is a very simple operation you want do do. Go over each line, print it, and if the current line is a date, extract the month and print an additional line.
Here's an example python script that does that.
import re
months = ["January", "February", "March", "April", "May", "June", "July",
"August", "September", "October", "November", "December"]
with open(your_xml_file) as f:
for line in f:
print line
match = re.search(r'<Date>\d{4}-(?P<month>\d{2})-\d{2}</Date>', line)
if match is not None:
print months[int(match.group('month')) - 1]
Note, however that this will fail as soon as you insert whitespace or add something else like attributes to Date. That's why it's better to use a real parser. But if your format is exactly like you stated, then it is faster to just write a small throw away script like this.

Answer 2

so just for the record this is my final code which adds another regex substitution and outputs everything in a new file:
x = 'marco_2013_24_08' #filename without extension
import re
months = ["<Month>gennaio</Month>", "<Month>febbraio</Month>", "<Month>marzo</Month>", "<Month>aprile</Month>", "<Month>maggio</Month>", "<Month>giugno</Month>", "<Month>luglio</Month>",
"<Month>agosto</Month>", "<Month>settembre</Month>", "<Month>ottobre</Month>", "<Month>novembre</Month>", "<Month>dicembre</Month>"]
import sys
sys.stdout = open('_' + x + 'regexed.xml', 'w')
with open(x + '.xml') as f:
for line in f:
im = re.sub(r'<Message>Image\:\ .+\/(IMG.+\.jpg)<\/Message>',r'<Image href="Bilder/\1"></Image>',line)
print im
mm = re.search(r'<Date>\d{4}-(?P<month>\d{2})-\d{2}</Date>', line)
if mm is not None:
print months[int(mm.group('month')) - 1]