# DeleteCases

DeleteCases[expr,pattern]

removes all elements of expr that match pattern.

DeleteCases[expr,pattern,levelspec]

removes all parts of expr on levels specified by levelspec that match pattern.

DeleteCases[expr,pattern,levelspec,n]

removes the first n parts of expr that match pattern.

DeleteCases[pattern]

represents an operator form of DeleteCases that can be applied to an expression.

# Details and Options

• When used on an Association, DeleteCases deletes elements according to their values.
• DeleteCases[pattern][expr] is equivalent to DeleteCases[expr,pattern].
• With the option , you can delete heads with DeleteCases. Deleting the head of a particular element in an expression is equivalent to applying FlattenAt to the expression at that point.
• DeleteCases uses standard level specifications:
•  n levels 1 through n Infinity levels 1 through Infinity {n} level n only {n1,n2} levels n1 through n2
• The default value for levelspec in DeleteCases is {1}.
• A positive level n consists of all parts of expr specified by n indices.
• A negative level -n consists of all parts of expr with depth n.
• Level -1 consists of numbers, symbols, and other objects that do not have subparts.
• Level 0 corresponds to the whole expression.
• DeleteCases traverses the parts of expr in a depth-first order, with leaves visited before roots.

# Examples

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## Basic Examples(5)

Delete cases that match integers:

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Use the operator form:

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Delete elements from Association:

 In[1]:=
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DeleteCases can access parts of the elements of an Association:

 In[1]:=
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Deleting elements from a nested Association:

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