MissingQ

MissingQ[expr]

expr の頭部がMissingのときにTrueを返す．

例題

すべて開くすべて閉じる

例  (1)

式の頭部がMissingかどうかの検定を行う：

特性と関係  (2)

MissingQがFalseを与える値を選ぶことはDeleteMissingに等しい：

連想中にないキーはMissing["KeyAbsent",…]を返す：

MissingQを使ってそのような結果を検知する：

考えられる問題  (1)

MissingQは，Missingそれ自体である記号に対してはTrueを返さない：

Wolfram Research (2015), MissingQ, Wolfram言語関数， https://reference.wolfram.com/language/ref/MissingQ.html.

テキスト

Wolfram Research (2015), MissingQ, Wolfram言語関数， 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 ]}