# Level

Level[expr,levelspec]

gives a list of all subexpressions of expr on levels specified by levelspec.

Level[expr,levelspec,f]

applies f to the sequence of subexpressions.

# Details and Options

• Level uses standard level specifications:
•  n levels 1 through Infinity levels 1 through Infinity {n} level only {n1,n2} levels through
• Level[expr,{-1}] gives a list of all "atomic" objects in expr.
• A positive level consists of all parts of expr specified by indices.
• A negative level consists of all parts of expr with depth .
• Level 0 corresponds to the whole expression.
• With the option setting , Level includes heads of expressions and their parts.
• Level traverses expressions in depthfirst order, so that the subexpressions in the final list are ordered lexicographically by their indices.

# Examples

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## Basic Examples(6)

Give all parts at level -1:

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Give all parts down to level 2:

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Give all parts at levels 0 through infinity:

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Get all leaves from an Association:

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Values in an Association are at the first level:

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Give elements from nested associations:

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 In[2]:=
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