Missing

Missing[]

represents data that is missing.

Missing["reason"]

specifies a reason for the data's being missing.

Missing["reason",expr]

associates the expression expr with the missing data.

Details

  • Missing[] is a symbolic object, with no default evaluation rules defined.
  • Typical examples of "reason" include "NotApplicable", "Unknown", "NotAvailable", "Nonexistent", "Indeterminate", "Variable", "Disputed", or "TooLarge".
  • Missing can be returned by most data functions, such as CountryData and ElementData.
  • Missing is returned when a key requested in an Association is not found.
  • Plotting functions automatically omit Missing objects when plotting data.
  • In TraditionalForm, Missing is typically formatted as , with a tooltip specifying the reason.

Examples

Basic Examples  (4)

When properties are missing, a Missing object is returned:

Missing is generated when an association does not contain the specified key:

Missing elements can be filtered out using DeleteCases:

Visualization typically automatically filters out Missing elements:

Wolfram Research (2007), Missing, Wolfram Language function, https://reference.wolfram.com/language/ref/Missing.html (updated 2014).

Text

Wolfram Research (2007), Missing, Wolfram Language function, https://reference.wolfram.com/language/ref/Missing.html (updated 2014).

BibTeX

@misc{reference.wolfram_2021_missing, author="Wolfram Research", title="{Missing}", year="2014", howpublished="\url{https://reference.wolfram.com/language/ref/Missing.html}", note=[Accessed: 24-October-2021 ]}

BibLaTeX

@online{reference.wolfram_2021_missing, organization={Wolfram Research}, title={Missing}, year={2014}, url={https://reference.wolfram.com/language/ref/Missing.html}, note=[Accessed: 24-October-2021 ]}

CMS

Wolfram Language. 2007. "Missing." Wolfram Language & System Documentation Center. Wolfram Research. Last Modified 2014. https://reference.wolfram.com/language/ref/Missing.html.

APA

Wolfram Language. (2007). Missing. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/Missing.html