The Answer Your sequence functions marked “returns NIL” will return T if you pass :test #’equalp to them. The Reason The default Two-Argument Test in Common Lisp is eql. It is the most reasonable choice between the 4(!) general purpose comparison functions provided for by the ANSI CL standard: eq is too implementation-dependent and does … Read more
In The Art of Computer Programming, Volume 2: Seminumerical Algorithms, Third Edition, Knuth describes the following selection sampling algorithm: Algorithm S (Selection sampling technique). To select n records at random from a set of N, where 0 < n ≤ N. S1. [Initialize.] Set t ← 0, m ← 0. (During this algorithm, m represents … Read more
The righteous path You might want to reconsider normalizing your schema. It is not necessary for everyone to “join for even the simplest query”. Create a VIEW for that. Table could look like this: CREATE TABLE hostname ( hostname_id serial PRIMARY KEY , host_id int REFERENCES host(host_id) ON UPDATE CASCADE ON DELETE CASCADE , hostname … Read more
“Jagged array” is slang for array of arrays. VBA’sVariant data type can contain just about anything*, including an array. So you make an array of type Variant, and assign to each of its elements an array of arbitrary length (i.e. not all of them have to have equal length). Here’s an example: Dim nStudents As … Read more
You can pass this to each block. See here: http://jsfiddle.net/yR7TZ/1/ {{#each this}} <div class=”row”></div> {{/each}}
This works: CREATE OR REPLACE FUNCTION avg_purchases(last_names text[] = ‘{}’) RETURNS TABLE(last_name text, avg_purchase_size float8) LANGUAGE sql AS $func$ SELECT last_name, avg(purchase_size)::float8 FROM purchases WHERE last_name = ANY($1) GROUP BY last_name $func$; Call: SELECT * FROM avg_purchases(‘{foo,Bar,baz,”}weird_name”$$”}’); Or (example with dollar-quoting): SELECT * FROM avg_purchases($x${foo,Bar,baz,”}weird_name’$$”}$x$); How to quote string literals: Insert text with single quotes … Read more
Here’s a multi-column and a single-column QuickSort for VBA, modified from a code sample posted by Jim Rech on Usenet. Notes: You’ll notice that I do a lot more defensive coding than you’ll see in most of the code samples out there on the web: this is an Excel forum, and you’ve got to anticipate … Read more
I’ve done this in an interview before, and one of the most elegant/efficient ways to do this is O(n log k). with space: O(k) (thanks, @Nzbuu) Basically you’re going to use a max-heap of size limited to k. For each item in the array, check to see if it’s smaller than the max (only O(1)). … Read more
I had exactly the same problem last week and thought about it for quite a while. It seems, that associative arrays can’t be serialized or copied. There’s a good Bash FAQ entry to associative arrays which explains them in detail. The last section gave me the following idea which works for me: function print_array { … Read more
See the Parameter Expansion section in the Bash man page. A[@] returns the contents of the array, :1:2 takes a slice of length 2, starting at index 1. A=( foo bar “a b c” 42 ) B=(“${A[@]:1:2}”) C=(“${A[@]:1}”) # slice to the end of the array echo “${B[@]}” # bar a b c echo “${B[1]}” … Read more