MissingQ

MissingQ[expr]

gives True if expr has head Missing.

Examples

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Basic Examples  (1)

Test whether an expression has head Missing:

Properties & Relations  (2)

Selecting values for which MissingQ gives False is equivalent to DeleteMissing:

Keys not present in an association will return Missing["KeyAbsent",…]:

Use MissingQ to detect such results:

Possible Issues  (1)

MissingQ does not yield True for the symbol Missing itself:

Wolfram Research (2015), MissingQ, Wolfram Language function, https://reference.wolfram.com/language/ref/MissingQ.html.

Text

Wolfram Research (2015), MissingQ, Wolfram Language function, https://reference.wolfram.com/language/ref/MissingQ.html.

CMS

Wolfram Language. 2015. "MissingQ." Wolfram Language & System Documentation Center. Wolfram Research. https://reference.wolfram.com/language/ref/MissingQ.html.

APA

Wolfram Language. (2015). MissingQ. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/MissingQ.html

BibTeX

@misc{reference.wolfram_2024_missingq, author="Wolfram Research", title="{MissingQ}", year="2015", howpublished="\url{https://reference.wolfram.com/language/ref/MissingQ.html}", note=[Accessed: 21-November-2024 ]}

BibLaTeX

@online{reference.wolfram_2024_missingq, organization={Wolfram Research}, title={MissingQ}, year={2015}, url={https://reference.wolfram.com/language/ref/MissingQ.html}, note=[Accessed: 21-November-2024 ]}