Arrays
An array is an object with components arranged according to a rectilinear coordinate system. One-dimensional arrays are called vectors.
A general array may contain any Lisp object, whereas a specialized array contains elements restricted to a specified type. Vectors whose elements are restricted to type string-char are called strings. Vectors whose elements are restricted to type bit are called bit-vectors.
Create
make-array dims &key type initial-element initial-contents adjustable fill-pointer displaced-to displaced-index-offset ⇒ new-array
(make-array '(2 3)) ;⇒ #2A((0 0 0) (0 0 0))
(make-array 5 :fill-pointer 0 :adjustable t :element-type 'character) ;⇒ ""adjust-array array new-dims &key type initial-element initial-contents fill-pointer displaced-to displaced-index-offset ⇒ adjusted-array
alexandria:copy-array array &key element-type fill-pointer adjustable ⇒ new-array
Returns an undisplaced copy of array, with same fill-pointer and adjustability as the original.
Select
aref array &rest subscripts ⇒ element
Access array elements. Related: svref —Access index of a simple vector.
(setf a (make-array '(2 2) :initial-contents '((1 2) (3 4))))
(aref a 1 1) ;⇒ 4
(setf (aref a 0 1) 99) ; a ⇒ #2A((1 99) (3 4))row-major-aref array index ⇒ element
Considers array as a vector by viewing its elements in row-major order, and returns the element of that vector which is referred to by the given index.
array-row-major-index array subscripts* ⇒ index
Computes the position according to the row-major ordering of array for the element that is specified by subscripts, and returns the offset of the element in the computed position from the beginning of array.
array-dimensions array ⇒ dimensions
Returns a list of the dimensions of array. (If array is a vector with a fill pointer, that fill pointer is ignored.)
(array-dimensions (make-array 4)) ;⇒ (4)
(array-dimensions (make-array '(2 3))) ;⇒ (2 3)
(array-dimensions (make-array 4 :fill-pointer 2)) ;⇒ (4)array-dimension array axis-number ⇒ dimension
Returns the axis-number dimension[1] of array. (Any fill pointer is ignored.)
(array-dimension (make-array 4) 0) ;⇒ 4
(array-dimension (make-array '(2 3)) 1) ;⇒ 3array-total-size array ⇒ size
Returns the array total size of the array.
(array-total-size (make-array 4)) ;⇒ 4
(array-total-size (make-array 4 :fill-pointer 2)) ;⇒ 4
(array-total-size (make-array 0)) ;⇒ 0
(array-total-size (make-array '(4 2))) ;⇒ 8
(array-total-size (make-array '(4 0))) ;⇒ 0
(array-total-size (make-array '())) ;⇒ 1array-rank array ⇒ rank
Returns the number of dimensions of array.
(array-rank (make-array '())) ;⇒ 0
(array-rank (make-array 4)) ;⇒ 1
(array-rank (make-array '(4))) ;⇒ 1
(array-rank (make-array '(2 3))) ;⇒ 2array-displacement array ⇒ displaced-to, displaced-index-offset
If the array is a displaced array, returns the values of the :displaced-to and :displaced-index-offset options for the array (see the functions make-array and adjust-array). If the array is not a displaced array, nil and 0 are returned.
array-rank-limit
Constant.
array-dimension-limit
Constant.
array-total-size-limit
Constant variable. The upper exclusive bound on the array total size of an array.
elt seq idx ⇒ element
Related: nth, nthcdr, car, cdr, first … tenth
(setf seq '(a b c))
(elt seq 1) ;⇒ B
(setf (elt seq 1) "hi") ; seq ⇒ (A "hi" C)alexandria:random-elt
Return a random element from a sequence.
length seq ⇒ n
(length '(a b c)) ;⇒ 3
(length "hello") ;⇒ 5find item seq &key from-end test test-not start end key ⇒ element
If the sequence seq contains an element satisfying test, then the leftmost such element is returned; otherwise nil is returned. Functional variants are find-if and find-if-not.
(find 3 '(1 2 3 4 5)) ;⇒ 3
(find-if #'oddp '(1 2 3 4 5) :end 3 :from-end t) ;⇒ 3position item seq &key from-end test test-not start end key ⇒ idx
Return the first index position of an item in the sequence, otherwise nil.
(position #\a "baobab" :from-end t) ;⇒ 4
(position-if #'oddp '((1) (2) (3) (4)) :start 1 :key #'car) ;⇒ 2count item seq &key from-end start end key test test-not ⇒ n
The number of elements in the specified subsequence of seq. Functional variants are count-if and count-if-not.
(count 'a '(a b c a)) ;⇒ 2
(count-if #'oddp '(1 2 3)) ;⇒ 2cl-utilities:extremum seq fn &key key (start 0) end ⇒ smallest-element
Returns first element of sequence if it were ordered by sort using the predicate fn. extrema is similar but returns a list of values since there may be more than one extremum determined by the predicate. n-most-extreme returns a list of n values of a sorted sequence. ref
(extremum '(1 2 9 7 3 2) #'>) ;⇒ 9
(extrema '(1 2 9 7 3 2) #'>) ;⇒ (9)
(n-most-extreme 3 '(1 2 9 7 3 2) #'>) ;⇒ (9 7 3)subseq seq start &optional end ⇒ sub-seq
Returns the sub-sequence of seq specified by start and end.
(setf str "hello")
(subseq str 2 4) ;⇒ "ll"
(setf (subseq str 2 4) "ad") ; str ⇒ "heado"search seq1 seq2 &key from-end test test-not key start1 start2 end1 end2 ⇒ idx
Searches sequence seq2 for a sub-sequence that matches seq1. Returns its index position.
(search '(c d) '(a b c d)) ;⇒ 2
(search "bar" "foobarbaz") ;⇒ 3mismatch seq1 seq2 &key from-end test test-not key start1 start2 end1 end2 ⇒ idx
Return the index position where two sequences diverge.
(mismatch "foobarbaz" "foom") ;⇒ 3