Regular expression, can I use it for this task?

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Hi
I am working on a program that needs to lookup information in a XML file, formatted like this: http://www.hrdsoftwarellc.com/hrdxmlcountries/LogbookCountryDataEx.xml

The tag "PrefixList" is the field I intend to use and my problem is to find a nice way to do it.

My program need to find out from which country a radio amateur call sign is located.

I the call sign is located in Denmark the PrefixList tag is:
PrefixList="5[PQ].*|O[UVZ].*"

Call sign examples: OZ1BV, 5Q5P, 5P9XYZ, UO9S, OV5RT, ect.

If the call sign is located in Germany the PrefixList tag is:
PrefixList="D[A-R].*"

Call sign examples: DA7T, DB4TY, DC2EW, DR8RE, ect.

Canada:
PrefixList="C[FGJK].*|C[HY][12].*|C[IZ][012].*|V[ABCEGX].*|V[DO][12].*|V[FY][012].*|X[JN][12].*|X[KO][012].*|X[LM].*"

Can this problem solved using a regular expression?

Best regards, Brian

Posted 6-Sep-15 8:41am

Member 9584445

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Zoltán Zörgő 6-Sep-15 16:22pm

I don't get your problem: these PrefixList attributes contain valid regular expressions. I suppose, you would like to match them against UniqueCalls001.item.Callsign attributes.
Just do it. What you want exactly to achieve? Where are you stuck?

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**Zoltán Zörgő** · Accepted Answer · 2015-09-06T10:54:00

Solution 1

Something like this:

C#

var xml = XDocument.Load(@"http://www.hrdsoftwarellc.com/hrdxmlcountries/LogbookCountryDataEx.xml");

var cs = from c in xml.Root.Elements("Countries001").Elements("item")
         select new
         {
         Latitude=c.Attribute("Latitude").Value,
         Longitude=c.Attribute("Longitude").Value,
         re = new Regex(c.Attribute("PrefixList").Value, RegexOptions.IgnoreCase)
         };

var us = from u in xml.Root.Elements("UniqueCalls001").Elements("item")
         let c = cs.FirstOrDefault( x=> x.re.IsMatch(u.Attribute("Callsign").Value))
         select new
         {
         CallSign = u.Attribute("Callsign").Value,
         Latitude = c.Latitude,
         Longitude = c.Longitude
         };

us.Dump();

Posted 6-Sep-15 10:54am

Zoltán Zörgő

Updated 6-Sep-15 10:55am

v2

Comments

Member 9584445 7-Sep-15 15:38pm

Hi Zoltán and thanks for Your solution

I am not able to figure out how to use it. What I need is to send a callsign (eg. OZ1BV, to a function and get the country returned, in this case Denmark.

Best regards, Brian

Zoltán Zörgő 7-Sep-15 15:40pm

That's even simpler.


var xml = XDocument.Load(@"http://www.hrdsoftwarellc.com/hrdxmlcountries/LogbookCountryDataEx.xml");
 
var cs = from c in xml.Root.Elements("Countries001").Elements("item")
		 let re = new Regex(string.Format("^{0}$",c.Attribute("PrefixList").Value), RegexOptions.IgnoreCase)
         where re.IsMatch("OZ1BV")
		 select c.Attribute("Country").Value;		 
		 
cs.Dump();

I hope you can wrap a class or at least a method around it yourself.
But have you noticed that UniqueCalls001.item elements already have country attribute?

Member 9584445 8-Sep-15 6:42am

Yes, I will wrap my own class around it.
UniqueCalls001 is a very special part only containing a few callsigns.

Member 9584445 8-Sep-15 8:16am

btw: Forgot to say thanks a lot - it's working perfect :-)

Zoltán Zörgő 8-Sep-15 9:39am

You are welcome

Member 9584445 8-Sep-15 10:01am

Found a little bug: The callsign "VP8VPC" results in "Falkland Is." (Correct) and "DPR of Korea (North Korea)" (Wrong). Can You figure out how to adjust the Rex. Ex.?

Zoltán Zörgő 8-Sep-15 10:05am

The problem is the OR (|). You need to exclude partial match. This will do it:


var cs = from c in xml.Root.Elements("Countries001").Elements("item")
let exp = c.Attribute("PrefixList").Value
let re = new Regex(string.Format("^{0}$", exp.Replace("|","$|^")), RegexOptions.IgnoreCase)
where re.IsMatch("VP8VPC")
select c.Attribute("Country").Value;

Member 9584445 8-Sep-15 10:19am

Perfect! Again, thanks a lot.
I must learn how to use reg. ex. It is really very useful :-)

Zoltán Zörgő 8-Sep-15 13:38pm

Yes, regex is a great tool.

Member 9584445 23-Sep-15 8:25am

Hi again, Zoltán

I ran into that the callsign "NG3Y" cannot be linked to USA.
Can it be because of this part A[A-GI-K] (GI - there is no separator between)

<item arrlprefix="K" comment="" continent="NA" country="United States" cqzone="5" dxcc="291" ituzone="6" latitude="39.0000N" longitude="97.5278W" prefixlist="[KNW][0-9].*|A[A-GI-K].*|[KNW][A-FI-KM-OQ-Z].*|KP[06-9].*|KG[0-35-9].*|KG4[A-Z]|KG4[A-Z][A-Z][A-Z]" status="Active" startdate="" enddate="" geoid="244" wiki="http://en.wikipedia.org/wiki/United_States_of_America">

Best regards, Brian

Zoltán Zörgő 24-Sep-15 6:00am

Test the expression in any regular expression tester.

Member 9584445 24-Sep-15 7:29am

Thanks a lot for replying, Zoltán.

I get the same result, no Country can be found. I don't know how to fix this since I have not yet gotten enough knowledge about RegEx.

Best regards, Briann

Zoltán Zörgő 24-Sep-15 9:02am

If teh expression is wrong, that it is wrong. What do you expect from me?

Member 9584445 24-Sep-15 9:09am

I was hoping You could fix the rexex so the lookup will work and in this case return "USA" for the call "NG3Y"

Best regards, Brian

Zoltán Zörgő 24-Sep-15 10:44am


[KNW][0-9].*
A[A-GI-K].*
[KNW][A-FI-KM-OQ-Z].*
KP[06-9].*
KG[0-35-9].*
KG4[A-Z]
KG4[A-Z][A-Z][A-Z]

We are good.

But NG3Y won't match any of them. A regex is either good or not good. But you can't fix it to match something that it should not.

Member 9584445 25-Sep-15 3:34am

Okay - I get it.
The problem is that:
- [KNW] means letters K, N or W are allowed
- [A-GI-K] means letters in the range A to G and I to K are allowed
Therefore I have to find a way to resolve this call, NG3Y, to belong to USA.

Best regards, Brian

Zoltán Zörgő 25-Sep-15 3:50am

Yes, but there is no such subexpression! [KNW] is from the first, [A-GI-K] is from the second. But these are two different branches.

Member 9584445 25-Sep-15 4:13am

You are right. The list seems to be missing an update.
This: [KNW][A-FI-KM-OQ-Z].*
Have to be: [KNW][A-GI-KM-OQ-Z].*
to give the correct result. I will contact the provider.

Thanks again for Your kindly replies.
Have a nice weekend.

Best regards, Brian