-
Something for the weekend?
A challenge for the weekend? Something from the Vector D?j?
A single-expression function to replace multiple embedded spaces in a string with single spaces. E.g.
q)rmeb “the quick brown fox” “the quick brown fox”
If you find yourself writing a loop, you’re on the wrong track. This is not a golfing challenge, but my best lambda is 26 chars.
Extra kudos Find the fastest expression on a million-char string.
Even more kudos To avoid typing it so often, you have a general filter function
f:{y where x@y}. Definermebas a projection off, using a composition as the left argument. -
5 Replies
-
A surprise? Char is a sortable type and Less Than is as fast as Equals and faster than Not Equals.
q)ts:100000 “quick brown fox”>” ”
13 752
q)ts:100000 “quick brown fox”<>” ”
27 880
q)ts:100000 “quick brown fox”=” ”
13 752
q)ts:100000 not”quick brown fox”=” ”
23 864
-
Hint: there is a faster test than
x=" "ornull x. -
{x where not(&’:)” “=x} / 23 chars and fast f[not(&’:)” “=] / as a projection
-
One thing to consider is that the seed value for the derived function means any leading blanks will be removed. Can use prev
q){x where not(&':)" "=x}s:" the quick brown fox " "the quick brown fox " q){x where not n&prev n:null x}s " the quick brown fox " -
Masking is nice but as an alternative & still taking care not to remove leading blanks
q){x where 1b,1_not” “~’:x}s:” the quick brown fox ” ” the quick brown fox ”
Appears to be faster
q)S:10000000#s q)ts:5 {x where not n&prev n:null x}S 197 100663904 q)ts:5 {x where 1b,1_not" "~':x}S 147 83886816caching taking place?
q)ts:5 {x where not n&prev n:null x}S 144 100663904 q)ts:5 {x where 1b,1_not" "~':x}S 148 83886816
Log in to reply.