<?xml version="1.0" encoding="latin1" ?> <!DOCTYPE erlref SYSTEM "erlref.dtd"> <erlref> <header> <copyright> <year>2007</year><year>2009</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> The contents of this file are subject to the Erlang Public License, Version 1.1, (the "License"); you may not use this file except in compliance with the License. You should have received a copy of the Erlang Public License along with this software. If not, it can be retrieved online at http://www.erlang.org/. Software distributed under the License is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License for the specific language governing rights and limitations under the License. </legalnotice> <title>array</title> <prepared></prepared> <responsible></responsible> <docno>1</docno> <approved></approved> <checked></checked> <date></date> <rev>A</rev> <file>array.xml</file></header> <module>array</module> <modulesummary>Functional, extendible arrays.</modulesummary> <description> <p>Functional, extendible arrays. Arrays can have fixed size, or can grow automatically as needed. A default value is used for entries that have not been explicitly set.</p> <p>Arrays uses <em>zero</em> based indexing. This is a deliberate design choice and differs from other erlang datastructures, e.g. tuples.</p> <p>Unless specified by the user when the array is created, the default value is the atom <c>undefined</c>. There is no difference between an unset entry and an entry which has been explicitly set to the same value as the default one (cf. <seealso marker="#reset-2">reset/2</seealso>). If you need to differentiate between unset and set entries, you must make sure that the default value cannot be confused with the values of set entries.</p> <p>The array never shrinks automatically; if an index <c>I</c> has been used successfully to set an entry, all indices in the range [0,<c>I</c>] will stay accessible unless the array size is explicitly changed by calling <seealso marker="#resize-2">resize/2</seealso>.</p> <p>Examples: </p><pre> %% Create a fixed-size array with entries 0-9 set to 'undefined' A0 = array:new(10). 10 = array:size(A0). %% Create an extendible array and set entry 17 to 'true', %% causing the array to grow automatically A1 = array:set(17, true, array:new()). 18 = array:size(A1). %% Read back a stored value true = array:get(17, A1). %% Accessing an unset entry returns the default value undefined = array:get(3, A1). %% Accessing an entry beyond the last set entry also returns the %% default value, if the array does not have fixed size undefined = array:get(18, A1). %% "sparse" functions ignore default-valued entries A2 = array:set(4, false, A1). [{4, false}, {17, true}] = array:sparse_to_orddict(A2). %% An extendible array can be made fixed-size later A3 = array:fix(A2). %% A fixed-size array does not grow automatically and does not %% allow accesses beyond the last set entry {'EXIT',{badarg,_}} = (catch array:set(18, true, A3)). {'EXIT',{badarg,_}} = (catch array:get(18, A3)).</pre></description> <section><title>DATA TYPES</title><marker id="types"/> <taglist> <tag><c>array()</c></tag> <item><marker id="type-array"/> <p>A functional, extendible array. The representation is not documented and is subject to change without notice. Note that arrays cannot be directly compared for equality.</p> </item> </taglist></section> <funcs> <func> <name>default(Array::array()) -> term()</name> <fsummary>Get the value used for uninitialized entries.</fsummary> <desc><marker id="default-1"/> <p>Get the value used for uninitialized entries. </p> <p><em>See also:</em> <seealso marker="#new-2">new/2</seealso>.</p> </desc></func> <func> <name>fix(Array::array()) -> array()</name> <fsummary>Fix the size of the array.</fsummary> <desc><marker id="fix-1"/> <p>Fix the size of the array. This prevents it from growing automatically upon insertion; see also <seealso marker="#set-3">set/3</seealso>.</p> <p><em>See also:</em> <seealso marker="#relax-1">relax/1</seealso>.</p> </desc></func> <func> <name>foldl(Function, InitialAcc::term(), Array::array()) -> term()</name> <fsummary>Fold the elements of the array using the given function and initial accumulator value.</fsummary> <type> <v>Function = (Index::integer(), Value::term(), Acc::term()) -> term()</v></type> <desc><marker id="foldl-3"/> <p>Fold the elements of the array using the given function and initial accumulator value. The elements are visited in order from the lowest index to the highest. If <c>Function</c> is not a function, the call fails with reason <c>badarg</c>. </p> <p><em>See also:</em> <seealso marker="#foldr-3">foldr/3</seealso>, <seealso marker="#map-2">map/2</seealso>, <seealso marker="#sparse_foldl-3">sparse_foldl/3</seealso>.</p> </desc></func> <func> <name>foldr(Function, InitialAcc::term(), Array::array()) -> term()</name> <fsummary>Fold the elements of the array right-to-left using the given function and initial accumulator value.</fsummary> <type> <v>Function = (Index::integer(), Value::term(), Acc::term()) -> term()</v></type> <desc><marker id="foldr-3"/> <p>Fold the elements of the array right-to-left using the given function and initial accumulator value. The elements are visited in order from the highest index to the lowest. If <c>Function</c> is not a function, the call fails with reason <c>badarg</c>. </p> <p><em>See also:</em> <seealso marker="#foldl-3">foldl/3</seealso>, <seealso marker="#map-2">map/2</seealso>.</p> </desc></func> <func> <name>from_list(List::list()) -> array()</name> <fsummary>Equivalent to from_list(List, undefined). </fsummary> <desc><marker id="from_list-1"/> <p>Equivalent to <seealso marker="#from_list-2">from_list(List, undefined)</seealso>.</p> </desc></func> <func> <name>from_list(List::list(), Default::term()) -> array()</name> <fsummary>Convert a list to an extendible array.</fsummary> <desc><marker id="from_list-2"/> <p>Convert a list to an extendible array. <c>Default</c> is used as the value for uninitialized entries of the array. If <c>List</c> is not a proper list, the call fails with reason <c>badarg</c>. </p> <p><em>See also:</em> <seealso marker="#new-2">new/2</seealso>, <seealso marker="#to_list-1">to_list/1</seealso>.</p> </desc></func> <func> <name>from_orddict(Orddict::list()) -> array()</name> <fsummary>Equivalent to from_orddict(Orddict, undefined). </fsummary> <desc><marker id="from_orddict-1"/> <p>Equivalent to <seealso marker="#from_orddict-2">from_orddict(Orddict, undefined)</seealso>.</p> </desc></func> <func> <name>from_orddict(List::list(), Default::term()) -> array()</name> <fsummary>Convert an ordered list of pairs {Index, Value} to a corresponding extendible array.</fsummary> <desc><marker id="from_orddict-2"/> <p>Convert an ordered list of pairs <c>{Index, Value}</c> to a corresponding extendible array. <c>Default</c> is used as the value for uninitialized entries of the array. If <c>List</c> is not a proper, ordered list of pairs whose first elements are nonnegative integers, the call fails with reason <c>badarg</c>. </p> <p><em>See also:</em> <seealso marker="#new-2">new/2</seealso>, <seealso marker="#to_orddict-1">to_orddict/1</seealso>.</p> </desc></func> <func> <name>get(I::integer(), Array::array()) -> term()</name> <fsummary>Get the value of entry I.</fsummary> <desc><marker id="get-2"/> <p>Get the value of entry <c>I</c>. If <c>I</c> is not a nonnegative integer, or if the array has fixed size and <c>I</c> is larger than the maximum index, the call fails with reason <c>badarg</c>.</p> <p>If the array does not have fixed size, this function will return the default value for any index <c>I</c> greater than <c>size(Array)-1</c>.</p> <p><em>See also:</em> <seealso marker="#set-3">set/3</seealso>.</p> </desc></func> <func> <name>is_array(X::term()) -> bool()</name> <fsummary>Returns true if X appears to be an array, otherwise false.</fsummary> <desc><marker id="is_array-1"/> <p>Returns <c>true</c> if <c>X</c> appears to be an array, otherwise <c>false</c>. Note that the check is only shallow; there is no guarantee that <c>X</c> is a well-formed array representation even if this function returns <c>true</c>.</p> </desc></func> <func> <name>is_fix(Array::array()) -> bool()</name> <fsummary>Check if the array has fixed size.</fsummary> <desc><marker id="is_fix-1"/> <p>Check if the array has fixed size. Returns <c>true</c> if the array is fixed, otherwise <c>false</c>.</p> <p><em>See also:</em> <seealso marker="#fix-1">fix/1</seealso>.</p> </desc></func> <func> <name>map(Function, Array::array()) -> array()</name> <fsummary>Map the given function onto each element of the array.</fsummary> <type> <v>Function = (Index::integer(), Value::term()) -> term()</v></type> <desc><marker id="map-2"/> <p>Map the given function onto each element of the array. The elements are visited in order from the lowest index to the highest. If <c>Function</c> is not a function, the call fails with reason <c>badarg</c>. </p> <p><em>See also:</em> <seealso marker="#foldl-3">foldl/3</seealso>, <seealso marker="#foldr-3">foldr/3</seealso>, <seealso marker="#sparse_map-2">sparse_map/2</seealso>.</p> </desc></func> <func> <name>new() -> array()</name> <fsummary>Create a new, extendible array with initial size zero.</fsummary> <desc><marker id="new-0"/> <p>Create a new, extendible array with initial size zero.</p> <p><em>See also:</em> <seealso marker="#new-1">new/1</seealso>, <seealso marker="#new-2">new/2</seealso>.</p> </desc></func> <func> <name>new(Options::term()) -> array()</name> <fsummary>Create a new array according to the given options.</fsummary> <desc><marker id="new-1"/> <p>Create a new array according to the given options. By default, the array is extendible and has initial size zero. Array indices start at 0.</p> <p><c>Options</c> is a single term or a list of terms, selected from the following: </p><taglist> <tag><c>N::integer()</c> or <c>{size, N::integer()}</c></tag> <item><p>Specifies the initial size of the array; this also implies <c>{fixed, true}</c>. If <c>N</c> is not a nonnegative integer, the call fails with reason <c>badarg</c>.</p></item> <tag><c>fixed</c> or <c>{fixed, true}</c></tag> <item><p>Creates a fixed-size array; see also <seealso marker="#fix-1">fix/1</seealso>.</p></item> <tag><c>{fixed, false}</c></tag> <item><p>Creates an extendible (non fixed-size) array.</p></item> <tag><c>{default, Value}</c></tag> <item><p>Sets the default value for the array to <c>Value</c>.</p></item> </taglist><p> Options are processed in the order they occur in the list, i.e., later options have higher precedence.</p> <p>The default value is used as the value of uninitialized entries, and cannot be changed once the array has been created.</p> <p>Examples: </p><pre> array:new(100)</pre><p> creates a fixed-size array of size 100. </p><pre> array:new({default,0})</pre><p> creates an empty, extendible array whose default value is 0. </p><pre> array:new([{size,10},{fixed,false},{default,-1}])</pre><p> creates an extendible array with initial size 10 whose default value is -1. </p> <p><em>See also:</em> <seealso marker="#fix-1">fix/1</seealso>, <seealso marker="#from_list-2">from_list/2</seealso>, <seealso marker="#get-2">get/2</seealso>, <seealso marker="#new-0">new/0</seealso>, <seealso marker="#new-2">new/2</seealso>, <seealso marker="#set-3">set/3</seealso>.</p> </desc></func> <func> <name>new(Size::integer(), Options::term()) -> array()</name> <fsummary>Create a new array according to the given size and options.</fsummary> <desc><marker id="new-2"/> <p>Create a new array according to the given size and options. If <c>Size</c> is not a nonnegative integer, the call fails with reason <c>badarg</c>. By default, the array has fixed size. Note that any size specifications in <c>Options</c> will override the <c>Size</c> parameter.</p> <p>If <c>Options</c> is a list, this is simply equivalent to <c>new([{size, Size} | Options]</c>, otherwise it is equivalent to <c>new([{size, Size} | [Options]]</c>. However, using this function directly is more efficient.</p> <p>Example: </p><pre> array:new(100, {default,0})</pre><p> creates a fixed-size array of size 100, whose default value is 0. </p> <p><em>See also:</em> <seealso marker="#new-1">new/1</seealso>.</p> </desc></func> <func> <name>relax(Array::array()) -> array()</name> <fsummary>Make the array resizable.</fsummary> <desc><marker id="relax-1"/> <p>Make the array resizable. (Reverses the effects of <seealso marker="#fix-1">fix/1</seealso>.)</p> <p><em>See also:</em> <seealso marker="#fix-1">fix/1</seealso>.</p> </desc></func> <func> <name>reset(I::integer(), Array::array()) -> array()</name> <fsummary>Reset entry I to the default value for the array.</fsummary> <desc><marker id="reset-2"/> <p>Reset entry <c>I</c> to the default value for the array. If the value of entry <c>I</c> is the default value the array will be returned unchanged. Reset will never change size of the array. Shrinking can be done explicitly by calling <seealso marker="#resize-2">resize/2</seealso>.</p> <p>If <c>I</c> is not a nonnegative integer, or if the array has fixed size and <c>I</c> is larger than the maximum index, the call fails with reason <c>badarg</c>; cf. <seealso marker="#set-3">set/3</seealso> </p> <p><em>See also:</em> <seealso marker="#new-2">new/2</seealso>, <seealso marker="#set-3">set/3</seealso>.</p> </desc></func> <func> <name>resize(Array::array()) -> array()</name> <fsummary>Change the size of the array to that reported by sparse_size/1.</fsummary> <desc><marker id="resize-1"/> <p>Change the size of the array to that reported by <seealso marker="#sparse_size-1">sparse_size/1</seealso>. If the given array has fixed size, the resulting array will also have fixed size.</p> <p><em>See also:</em> <seealso marker="#resize-2">resize/2</seealso>, <seealso marker="#sparse_size-1">sparse_size/1</seealso>.</p> </desc></func> <func> <name>resize(Size::integer(), Array::array()) -> array()</name> <fsummary>Change the size of the array.</fsummary> <desc><marker id="resize-2"/> <p>Change the size of the array. If <c>Size</c> is not a nonnegative integer, the call fails with reason <c>badarg</c>. If the given array has fixed size, the resulting array will also have fixed size.</p> </desc></func> <func> <name>set(I::integer(), Value::term(), Array::array()) -> array()</name> <fsummary>Set entry I of the array to Value.</fsummary> <desc><marker id="set-3"/> <p>Set entry <c>I</c> of the array to <c>Value</c>. If <c>I</c> is not a nonnegative integer, or if the array has fixed size and <c>I</c> is larger than the maximum index, the call fails with reason <c>badarg</c>.</p> <p>If the array does not have fixed size, and <c>I</c> is greater than <c>size(Array)-1</c>, the array will grow to size <c>I+1</c>. </p> <p><em>See also:</em> <seealso marker="#get-2">get/2</seealso>, <seealso marker="#reset-2">reset/2</seealso>.</p> </desc></func> <func> <name>size(Array::array()) -> integer()</name> <fsummary>Get the number of entries in the array.</fsummary> <desc><marker id="size-1"/> <p>Get the number of entries in the array. Entries are numbered from 0 to <c>size(Array)-1</c>; hence, this is also the index of the first entry that is guaranteed to not have been previously set.</p> <p><em>See also:</em> <seealso marker="#set-3">set/3</seealso>, <seealso marker="#sparse_size-1">sparse_size/1</seealso>.</p> </desc></func> <func> <name>sparse_foldl(Function, InitialAcc::term(), Array::array()) -> term()</name> <fsummary>Fold the elements of the array using the given function and initial accumulator value, skipping default-valued entries.</fsummary> <type> <v>Function = (Index::integer(), Value::term(), Acc::term()) -> term()</v></type> <desc><marker id="sparse_foldl-3"/> <p>Fold the elements of the array using the given function and initial accumulator value, skipping default-valued entries. The elements are visited in order from the lowest index to the highest. If <c>Function</c> is not a function, the call fails with reason <c>badarg</c>. </p> <p><em>See also:</em> <seealso marker="#foldl-3">foldl/3</seealso>, <seealso marker="#sparse_foldr-3">sparse_foldr/3</seealso>.</p> </desc></func> <func> <name>sparse_foldr(Function, InitialAcc::term(), Array::array()) -> term()</name> <fsummary>Fold the elements of the array right-to-left using the given function and initial accumulator value, skipping default-valued entries.</fsummary> <type> <v>Function = (Index::integer(), Value::term(), Acc::term()) -> term()</v></type> <desc><marker id="sparse_foldr-3"/> <p>Fold the elements of the array right-to-left using the given function and initial accumulator value, skipping default-valued entries. The elements are visited in order from the highest index to the lowest. If <c>Function</c> is not a function, the call fails with reason <c>badarg</c>. </p> <p><em>See also:</em> <seealso marker="#foldr-3">foldr/3</seealso>, <seealso marker="#sparse_foldl-3">sparse_foldl/3</seealso>.</p> </desc></func> <func> <name>sparse_map(Function, Array::array()) -> array()</name> <fsummary>Map the given function onto each element of the array, skipping default-valued entries.</fsummary> <type> <v>Function = (Index::integer(), Value::term()) -> term()</v></type> <desc><marker id="sparse_map-2"/> <p>Map the given function onto each element of the array, skipping default-valued entries. The elements are visited in order from the lowest index to the highest. If <c>Function</c> is not a function, the call fails with reason <c>badarg</c>. </p> <p><em>See also:</em> <seealso marker="#map-2">map/2</seealso>.</p> </desc></func> <func> <name>sparse_size(A::array()) -> integer()</name> <fsummary>Get the number of entries in the array up until the last non-default valued entry.</fsummary> <desc><marker id="sparse_size-1"/> <p>Get the number of entries in the array up until the last non-default valued entry. In other words, returns <c>I+1</c> if <c>I</c> is the last non-default valued entry in the array, or zero if no such entry exists.</p> <p><em>See also:</em> <seealso marker="#resize-1">resize/1</seealso>, <seealso marker="#size-1">size/1</seealso>.</p> </desc></func> <func> <name>sparse_to_list(Array::array()) -> list()</name> <fsummary>Converts the array to a list, skipping default-valued entries.</fsummary> <desc><marker id="sparse_to_list-1"/> <p>Converts the array to a list, skipping default-valued entries. </p> <p><em>See also:</em> <seealso marker="#to_list-1">to_list/1</seealso>.</p> </desc></func> <func> <name>sparse_to_orddict(Array::array()) -> [{Index::integer(), Value::term()}]</name> <fsummary>Convert the array to an ordered list of pairs {Index, Value}, skipping default-valued entries.</fsummary> <desc><marker id="sparse_to_orddict-1"/> <p>Convert the array to an ordered list of pairs <c>{Index, Value}</c>, skipping default-valued entries. </p> <p><em>See also:</em> <seealso marker="#to_orddict-1">to_orddict/1</seealso>.</p> </desc></func> <func> <name>to_list(Array::array()) -> list()</name> <fsummary>Converts the array to a list.</fsummary> <desc><marker id="to_list-1"/> <p>Converts the array to a list. </p> <p><em>See also:</em> <seealso marker="#from_list-2">from_list/2</seealso>, <seealso marker="#sparse_to_list-1">sparse_to_list/1</seealso>.</p> </desc></func> <func> <name>to_orddict(Array::array()) -> [{Index::integer(), Value::term()}]</name> <fsummary>Convert the array to an ordered list of pairs {Index, Value}.</fsummary> <desc><marker id="to_orddict-1"/> <p>Convert the array to an ordered list of pairs <c>{Index, Value}</c>. </p> <p><em>See also:</em> <seealso marker="#from_orddict-2">from_orddict/2</seealso>, <seealso marker="#sparse_to_orddict-1">sparse_to_orddict/1</seealso>.</p> </desc></func></funcs> </erlref>