printing specific fields from a file

[Sam]

While learning, I'm trying to read a web log and extract few fields from it. The web log will be like below

147.172.225.10 - 16401 [16/Sep/2013:23:52:35 +0100] "GET /KBDOC-00057.html HTTP/1.0" 200 11761 "http://www.newbie.com"  "test F20L"
147.172.225.10 - 16401 [16/Sep/2013:23:52:35 +0100] "GET /theme.css HTTP/1.0" 200 12353 "http://www.newbie.com"  "test Mobile Browser Sorrento F20L"
23.53.29.101 - 32693 [16/Sep/2013:23:49:50 +0100] "GET /KBDOC-00035.html HTTP/1.0" 200 9337 "http://www.newbie.com"  "test Mobile Browser i3"

And I need to extract just the IP address and User id(3rd field) from the logs and print as

147.172.225.10/16401
147.172.225.10/16401
23.53.29.101/32693

I'm thinking of running a flatMap on each line splitting by ' ' and pick filed 1 and 3 and printing them with a / in between.
Could someone help me how and let me know if there is a better way to accomplish it. Thanks in advance !!

[Kevin Wright]

val src = Source fromFile "<your file name>"

val splitLines = src.lines map (_ split " ")  // is an Iterator[Array[String]]

val output = splitLines map { fields => fields(0) + "/" + fields(2) } // is an Iterator[String]

output forEach println

src.close()

Just be wary of the iterators here.  Instead of attempting to load the entire file into memory, lines will be parsed on demand.  This is great for performance and memory pressure, but also means that you must be careful to only close the source after you’ve finished processing it.

You’ll also want to avoid using those iterators more than once, they’ll already be consumed after the first use…

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"My point today is that, if we wish to count lines of code, we should not regard them as "lines produced" but as "lines spent": the current conventional wisdom is so foolish as to book that count on the wrong side of the ledger" ~ Dijkstra

[Sam]

Kevin, 

Thanks so much for the detailed explanation !!