Test for the existence of particular values using the any()
and all()
commands
Create a vector b
:
b <- c(7, 2, 4, 3, -1, -2, 3, 3, 6, 8, 12, 7, 3)
b
Use the function any()
to see if there is any element in b
equal -4 and less than 5:
any(b == -4)
any(b < 5)
Both commands work on logical vectors. Use any()
to check for missing data in a vector or an array.
d <- c(3, 2, NA, 5, 6, NA)
d
any(is.na(d))
Of course, we can check for non-missing data too.
any(!is.na(d))
The any()
command is helpful when checking for particular values in large data sets.
You can use the all()
command to check whether all elements in a given vector or array satisfy a particular condition. For example, let’s see whether all non-missing values in d
are less than 5. Here we note noting that the command is.na()
identifies missing data and that the syntax !is.na()
identifies non-missing data.
all(d[!is.na(d)] < 5)
Now check whether all non-missing elements are less than 7.
all(d[!is.na(d)] < 7)
The syntax above looks formidable. However, is.na()
identifies missing elements by creating a logical vector whose elements are either TRUE
or FALSE
.
is.na(d)
The syntax !is.na(d)
gives the opposite logical vector and counts non-missing data. Then, d[!is.na(d)]
gives the elements of d
that are-non missing. Finally, we apply the all()
command, and include the condition that all elements are less than 7.
That wasn’t so hard! In Blog 19 I will present another tip for data analysis in R.
See you later!
David
Annex: R codes used
# Create a vector b. b <- c(7, 2, 4, 3, -1, -2, 3, 3, 6, 8, 12, 7, 3) b # Check if there is any element in b equal -4 and less than 5: any(b == -4) any(b < 5) # Check for missing data in a vector d. d <- c(3, 2, NA, 5, 6, NA) d any(is.na(d)) # Check for non-missing data. any(!is.na(d)) # Check if all non-missing values in d are less than 5. all(d[!is.na(d)] < 5) # Check if all non-missing values in d are less than 7. all(d[!is.na(d)] < 7) # Identify missing elements in d. is.na(d)

Senior Academic Manager in New Zealand Institute of Sport and Director of Sigma Statistics and Research Ltd. Author of the book: R Graph Essentials.