At 00:38 -0400 2007/05/21, Terrence Brannon wrote:
On 5/21/07, Joey K Tuttle <[EMAIL PROTECTED]> wrote:
$ cat cs.ijs
echo +/ 0&". ;._2 stdin''
can you explain this to me? I know a good amount of it:
0&". you are creating a monadic verb which will convert its argument
to a number
+/ you are summing a list of numbers
;. _2 stdin '' NB. has me confused
-- is '' 2 single quotes or a single double quote
-- i dont see how ;. _2 stdin plays together
-- I dont understand ;. yet
cut (;.) is very powerful/useful, I recommend study of
the dictionary page. My use of it (;._2) applies the
left verb (0&". - which, as you say, converts a string
to a number with 0 as the replacement for ill-formed
numbers) to each line of the file excluding the line
ends (the single character LF) in Linux/Unix systems.
That does indeed return a vector of 1000 numbers from
the proscribed test file which is received via stdin''
(that is an empty right argument - 2 single 's) +/
is summation (+ inserted between each atom of the
vector) echo sends a result back out to the console
that is stdout (so it can be further piped if wanted).
Maybe some parentheses will help show associations -
echo +/ (0&". ;._2) stdin ''
Which I suppose you could "read in English" as:
echo the summation of all the numbers derived from
each line of the file received from standard input
Experimenting is always a good idea, to clarify what
happens - you could try something like:
$ cat bcs.ijs
echo 0&". ;._2 stdin ''
$ head sumcol-input.txt | ja bcs.ijs
276 498 _981 770 _401 702 966 950 _853 _53
$ tail sumcol-input.txt | ja bcs.ijs
_33 _965 752 474 _731 758 _573 4 38 264
That is, the first and last 10 numbers in the file.
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