Ulam spiral (for primes): Difference between revisions
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matrix 'signature': Matrix(101x101) 1208 dots
</pre>
=={{header|jq}}==
{{trans|Wren}}
{{works with|jq}}
'''Works with gojq, the Go implementation of jq'''
See [[Erdős-primes#jq]] for a suitable definition of `is_prime` as used here.
<lang jq>def array($init): [range(0; .) | $init];
# Test if input is a one-character string holding a digit
def isDigit:
type=="string" and length==1 and explode[0] as $c | (48 <= $c and $c <= 57);
def lpad($len): tostring | ($len - length) as $l | (" " * $l)[:$l] + .;
def generate($n; $i; $c):
if $n <= 1 then "'n' must be more than 1." | error
else { s: ($n|array(array(""))),
dir: "right",
y: (($n/2)|floor) }
| .x = if ($n % 2 == 0) then .y - 1 else .y end # shift left for even n
| reduce range($i; $n * $n + $i) as $j (.;
.s[.y][.x] = (
if $j | is_prime
then (if $c|isDigit then $j|lpad(4) else " \($c) " end)
else " ---"
end)
| if .dir == "right"
then if (.x <= $n - 1 and .s[.y - 1][.x] == "" and $j > i) then .dir = "up" else . end
elif .dir == "up"
then if (.s[.y][.x - 1] == "") then .dir = "left" else . end
elif .dir == "left"
then if (.x == 0 or .s[.y + 1][.x] == "") then .dir = "down" else . end
elif .dir == "down"
then if (.s[.y][.x + 1] == "") then .dir = "right" else . end
else .
end
| if .dir == "right" then .x += 1
elif .dir == "up" then .y += -1
elif .dir == "left" then .x += -1
elif .dir == "down" then .y += 1
else .
end )
| .s[] | join(" ")
end ;
# with digits
generate(9; 1; "0"), "",
# with *
generate(9; 1; "*")
</lang>
{{out}}
As for [[#Wren|Wren]].
=={{header|Julia}}==
| |||