DeleteMissing
DeleteMissing[list]
drops elements with head Missing from a list.
DeleteMissing[assoc]
drops elements whose values have head Missing from the association assoc.
DeleteMissing[expr,n]
applies DeleteMissing to any lists or associations that occur within the first n levels of expr.
DeleteMissing[expr,n,d]
considers an element at level n to be missing if Missing occurs within the first d levels of the element.
Details
- DeleteMissing[{lhs1->rhs1,…}] deletes any elements of the list when rhsi has head Missing.
- DeleteMissing[expr,Infinity] specifies that DeleteMissing should search to arbitrary depth for expressions with head Missing and delete them.
- DeleteMissing[expr,1,Infinity] indicates that elements at the first level should be removed if they contain Missing at any depth.
- When searching multiple levels, DeleteMissing will only search within lists and associations and ignores expressions with other heads.
- DeleteMissing[Missing[]] returns Sequence[].
Examples
open allclose allScope (3)
Delete elements with head Missing up to level 2:
Delete missing elements at all levels:
Delete elements at level 1 if they contain an element with head Missing:
Delete elements at level 1 if they contain a missing expression anywhere inside:
DeleteMissing deletes complete rules when the right-hand side is Missing:
Properties & Relations (2)
DeleteMissing[expr] deletes missing elements at the top level only:
DeleteMissing[list] is effectively equivalent to DeleteCases[list,_Missing]:
Possible Issues (1)
DeleteMissing does not enter heads other than List or Association:
Text
Wolfram Research (2014), DeleteMissing, Wolfram Language function, https://reference.wolfram.com/language/ref/DeleteMissing.html (updated 2015).
CMS
Wolfram Language. 2014. "DeleteMissing." Wolfram Language & System Documentation Center. Wolfram Research. Last Modified 2015. https://reference.wolfram.com/language/ref/DeleteMissing.html.
APA
Wolfram Language. (2014). DeleteMissing. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/DeleteMissing.html