Contains

Whether a collection has an element structurally equal to v.

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Contains(xs, v)$True$ if some element of $xs$ is structurally equal to $v$, else $False$.

Typed signatures

Type	Package	Applies
(collection<any>, element: any) -> boolean	compute-engine	always

Domain: Collections

Examples

Basic #

live ↗

In$\mathrm{Contains}(\bigl\lbrack1, 2, 3\bigr\rbrack, 2)$Out$\mathrm{True}$

live ↗

In$\mathrm{Contains}(\bigl\lbrack1, 2, 3\bigr\rbrack, 5)$Out$\mathrm{False}$

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In$\mathrm{Contains}(\bigl\lbrack1, 3, 4, 1, 2\bigr\rbrack, 2)$Out$\mathrm{True}$

Nothing is in the empty list

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In$\mathrm{Contains}(\bigl\lbrack\bigr\rbrack, x)$Out$\mathrm{False}$

Scope #

Symbolic elements

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In$\mathrm{Contains}(\bigl\lbrack x^2, y^2\bigr\rbrack, x^2)$Out$\mathrm{True}$

Elements can themselves be lists

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In$\mathrm{Contains}(\bigl\lbrack\bigl\lbrack1, 2\bigr\rbrack, \bigl\lbrack3, 4\bigr\rbrack\bigr\rbrack, \bigl\lbrack1, 2\bigr\rbrack)$Out$\mathrm{True}$

Only the top-level elements are searched

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In$\mathrm{Contains}(\bigl\lbrack\bigl\lbrack1, 2\bigr\rbrack, \bigl\lbrack3, 4\bigr\rbrack\bigr\rbrack, 1)$Out$\mathrm{False}$

A lazy Range is searched without being materialised

live ↗

In$\mathrm{Contains}(1..100, 50)$Out$\mathrm{True}$

Only top-level elements are searched, so the nested 0 is not found

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In$\mathrm{Contains}(\bigl\lbrack\bigl\lbrack1, 1, 3, 0\bigr\rbrack, \bigl\lbrack2, 1, 2, 2\bigr\rbrack\bigr\rbrack, 0)$Out$\mathrm{False}$

Properties #

Compared after canonical ordering, so $b + a$ matches $a + b$

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In$\mathrm{Contains}(\bigl\lbrack a+b\bigr\rbrack, b+a)$Out$\mathrm{True}$

Possible issues #

An exact and an approximate number with the same value match

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In$\mathrm{Contains}(\bigl\lbrack\frac{1}{2}\bigr\rbrack, 0.5)$Out$\mathrm{True}$

Repeated elements still count once: just a True/False answer

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In$\mathrm{Contains}(\bigl\lbrack1, 2, 1, 3\bigr\rbrack, 1)$Out$\mathrm{True}$

About

Examples	12
Checked against	Wolfram Language 11 agree1 differ
Crosswalk	Wolfram Language

See also: Any