Logical operators (AND, OR) with NA, TRUE and FALSE

by

To quote from ?Logic:

NA is a valid logical object. Where a component of x or y is NA, the
result will be NA if the outcome is ambiguous. In other words NA &
TRUE evaluates to NA, but NA & FALSE evaluates to FALSE. See the
examples below.

The key there is the word “ambiguous”. NA represents something that is “unknown”. So NA & TRUE could be either true or false, but we don’t know. Whereas NA & FALSE will be false no matter what the missing value is.

More Related Contents:

  1. Dealing with TRUE, FALSE, NA and NaN
  2. How to reshape data from long to wide format
  3. Grouping functions (tapply, by, aggregate) and the *apply family
  4. Reshaping multiple sets of measurement columns (wide format) into single columns (long format)
  5. Select the row with the maximum value in each group
  6. R memory management / cannot allocate vector of size n Mb
  7. Finding ALL duplicate rows, including “elements with smaller subscripts”
  8. Using ggplot2, can I insert a break in the axis?
  9. Change R default library path using .libPaths in Rprofile.site fails to work
  10. Installing older version of R package
  11. How to subset matrix to one column, maintain matrix data type, maintain row/column names?
  12. Why can’t R’s ifelse statements return vectors?
  13. Sample random rows in dataframe
  14. Extracting specific columns from a data frame
  15. Subset / filter rows in a data frame based on a condition in a column
  16. Converting year and month (“yyyy-mm” format) to a date?
  17. Fitting a density curve to a histogram in R
  18. A comprehensive survey of the types of things in R; ‘mode’ and ‘class’ and ‘typeof’ are insufficient
  19. What does %>% function mean in R?
  20. How do I install a package that has been archived from CRAN?
  21. as.Date with dates in format m/d/y in R
  22. How to order data by value within ggplot facets
  23. rank and order in R
  24. What’s the biggest R-gotcha you’ve run across?
  25. What is the difference between = and ==?
  26. Convert a dataframe to a vector (by rows)
  27. What is the difference between = and == in R?
  28. Should I use a data.frame or a matrix?
  29. Variable name restrictions in R
  30. Convert a vector into a list, each element in the vector as an element in the list

Leave a Comment