assertive v0.3-6


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Readable Check Functions to Ensure Code Integrity

Lots of predicates (is_* functions) to check the state of your variables, and assertions (assert_* functions) to throw errors if they aren't in the right form.


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An R package that provides readable check functions to ensure code integrity.

There are times when it is a good idea to check the state of your variables, to ensure that they have the properties that you think they have. For example, if you have a count variable, you might want to check that it is numeric, that all the values are non-negative, and that all the values are whole numbers.

assertive provides lots of functions ("predicates" and "assertions") to provide such checks. It is designed to make your code very easy to read, and to provide highly informative error messages.


To install the stable version, type:


To install the development version, you first need the devtools package.


Then you can install the assertive package using


How to use the package

assertive contains lots of assert functions ("assertions") that throw errors if conditions aren't met. They are very useful for checking user input to your functions.

For example,

f <- function(x)
  x + 1
## [1] 2
## Error in f(NULL) : x is NULL.

(You can think of the assert functions as more specific versions of base::stopifnot that make your code easier to read and give more informative error messages.)

Each assert function has a corresponding is function (a "predicate"). In this case, is_not_null is a wrapper to base-R's !is.null, that gives a more informative error message on failure (in an attribute named cause).

## [1] TRUE

## [1] FALSE
## Cause of failure:  NULL is NULL.

Many of the is functions are wrappers to base functions. They all return causes of failure, and they have consistent naming, beginning is_ or has_ (so base::interactive becomes is_interactive, for example.)

Vectorised is functions

Some is functions return a logical vector rather than a single value. In this case the input values are returned in the names to make it easier to see which values succeeded/failed, and the cause attribute is also vectorised.

For example,

is_positive(c(1, 0, -1, NA))
## There were 3 failures:
##   Position Value   Cause
## 1        2     0 too low
## 2        3    -1 too low
## 3        4  <NA> missing

Using unclass, you can see that this is just a logical vector, with a cause attribute.

unclass(is_positive(c(1, 0, -1, NA)))
##     1     0    -1  <NA> 
## attr(,"cause")
## [1]         too low too low missing

There are two corresponding assert functions for these vectorised is functions.

assert_any_are_positive(c(1, 0, -1, NA)) # test passed since 1 is positive
assert_all_are_positive(c(1, 0, -1, NA))
## Error: c(1, 0, -1, NA) contains non-positive values.
## There were 3 failures:
##   Position Value   Cause
## 1        2     0 too low
## 2        3    -1 too low
## 3        4  <NA> missing

Can't I just use testthat?

testthat is an excellent package for writing unit tests, and I recommend that you use it. Unit tests are a form of development-time testing. That is, you write the tests while you develop your code in order to check that you haven't made any mistakes.

assertive, and assertions in general, are for run-time testing. That is, you include them in your code to check that the user hasn't made a mistake while running your code.

The virtual package system

assertive is a virtual package; it does not contain any functions, but merely reexports them from lower-level packages. For a complete reference, see the individual package pages.

assertive.base contains the core functionality. For example, is_true checks when inputs return TRUE. It also contains some utility functions, such as use_first, which returns the first value of a vector, warning you if it was longer than length one. contains checks on properties of variables. For example, is_scalar checks for values that have length one, and has_duplicates checks for the presence of duplicate values.

assertive.types contains checks for types of variables. For example, is_character wraps the base is.character, while is_a_string combines that check with is_scalar to check for single strings.

assertive.numbers contains checks for numbers. For example, is_in_range checks if a number is in a numeric range.

assertive.strings contains checks for strings. For example, is_an_empty_string checks if a character vector contains a single empty string.

assertive.datetimes contains checks for dates and times. For example, is_in_past checks if a Date or POSIXt obejct is in the past.

assertive.files contains checks for files and connections. For example, is_readable_file checks if a path points to a file that R has permission to read, and is_file_connection check if an object is a file connection.

assertive.sets contains checks for sets. For example, is_subset checks if a vector is a subset of another vector.

assertive.matrices contains checks for matrices. For example, is_symmetric_matrix checks if a matrix is symmetric.

assertive.models contains checks for models. For example, is_empty_model checks if a model is the empty model (no factors). contains checks for complex data types. For example, is_credit_card_number checks a character vector for valid credit card numbers. contains checks for UK-specific complex data types. For example, is_uk_postcode checks a character vector for valid UK postcodes. contains checks for US-specific complex data types. For example, is_us_telephone_number checks a character vector for valid US telephone numbers.

assertive.reflection contains checks on the state of R. For example, is_solaris tests for that operating system, and is_rstudio tests for that IDE.

assertive.code contains checks for code. For example, is_valid_variable_name checks whether a character vector contains valid variable names.

I hate this; what's the alternative?

There are at least five other R packages for doing assertions. In alphabetical order of package:

I want to know more

There are several vignettes with more details on how to use the package, including case studies and exercises. Find them using


I want to help

The assertive packages are in the process of being translated into many languages. If you speak a language other than English, and have an hour or two spare, your translation skills would be appreciated.

assertive is also currently lacking assertions for time series, spatial data, personal data for countries other than the UK and US, and industry-sector-specific data. If you want to contribute a package for these data types, let me know and I can talk you through how to do it.

Functions in assertive

Name Description
has_any_attributes Does the input have any attributes?
is_closure_function Is the input a closure, builtin or special function?
is_array Is the input an array or matrix?
is_class Is the input the name of a (formally defined) class?
is_existing Does the variable exist? See is_existing.
is_existing_file Does the file exist?
has_arg Does the current call have an argument? See has_arg.
is_atomic Is the input atomic/recursive/vector?
is_debugged Is the input function being debugged? See is_debugged.
is_date_string Does the character vector contain dates?
has_attributes Does the input have the specified attributes?
call_and_name Call a function, and give the result names.
is_s3_generic Is the input an S3 generic or method?
is_ip_address Does the character vector contain IP addresses?
is_empty Is the input empty/scalar?
is_monotonic_increasing Is the vector monotonically increasing or decreasing?
is_nan Is the input (not) NaN?
is_empty_character Does the input contain empty or missing strings?
has_cols Does the input have rows/columns?
assertionError Condition classes
is_isbn_code Does the character vector contain ISBN book codes?
cause Get or set the "cause" attribute
false FALSE, with a cause of failure
has_slot Does the S4 input have a slot?
has_names Does the input have names?
coerce_to Coerce variable to a different class
is_batch_mode How is R running?
is_complex Is the input complex?
has_dims Does the input have dimensions?
dont_stop Run code without stopping
has_duplicates Does the input have duplicates?
is_binding_locked Is the binding of a variable locked? See is_binding_locked.
is_diagonal_matrix Is the input a diagonal matrix?
is_externalptr Is the input an external pointer?
is_connection Is the input a connection?
is_s4 Is the input an S4 object?
changes Important changes to assertive
is_credit_card_number Does the character vector contain credit card numbers?
get_name_in_parent Get the name of a variable in the parent frame
is_symmetric_matrix Is the input a symmetric matrix?
is_empty_file Is a file too big or small?
is_dir Is the path a directory?
is_date Is the input a date?
is_data.frame Is the input is a data.frame?
is_data.table Is the input a data.table?
is_honorific Is the string an honorific?
is_error_free Does the code run without throwing an error? See is_error_free.
is_executable_file Is the file accessible?
is_identity_matrix Is the input an identity matrix?
is_list Is the input a list?
is_library Is the directory a known R library?
is_empty_model Is the input the empty model?
is_in_range Is the input in range?
is_function Is the input a function?
is_factor Is the input a factor?
is_hex_color Does the character vector contain hex colors?
is_inherited_from Does the object inherit from some class?
is_valid_variable_name Is the string a valid variable name? See is_valid_variable_name.
is_table Is the input a table?
is_whole_number Is the input a whole number?
is_lower_triangular_matrix Is the matrix upper/lower triangular?
character_to_list_of_integer_vectors Convert a character vector to a list of integer vectors See character_to_list_of_integer_vectors.
is_on_os_path Is the path on the OS path?
is_numeric_string Does the string contain a number? See is_numeric_string.
is_rstudio_current Is RStudio the current version?
is_matching_fixed Does the string match a pattern? See is_matching_fixed.
is_single_character Is the input a single character? See is_single_character.
is_rstudio_desktop Is RStudio running in desktop or server mode?
is_real Is the input real/imaginary?
is_relistable Is the input relistable?
is_in_past Is the input in the past/future?
is_if_condition Is suitable to be used as an if condition See is_if_condition.
is2 Alternative version of is
has_terms Does the input have terms?
is_cas_number Does the character vector contain CAS registry numbers?
is_square_matrix Is the input a square matrix?
is_email_address Does the character vector contain email addresses?
is_character Is the input of type character?
is_divisible_by Is the input divisible by a number?
is_us_zip_code Is the string a valid US zip code?
is_valid_r_code Is the input valid R code? See is_valid_r_code.
r_can_find_tools Can R find tools?
is_environment Is the input an environment?
is_logical Is the input logical?
is_loaded Is the input DLL loaded? See is_loaded.
is_language Is the input a language object?
is_tbl Is the input a tbl?
is_equal_to How does the input relate to a value?
is_internal_function Is the input an internal function?
is_formula Is the input a formula?
is_integer Is the input an integer?
is_null Checks to see if the input is (not) null.
is_finite Are the inputs (in)finite?
is_uk_national_insurance_number Is the string a valid UK national insurance number?
is_uk_postcode Is the string a valid UK postcode?
r_has_jpeg_capability Does R have a capability?
is_numeric Is the input numeric?
is_r Are you running R?
is_windows What OS is running?
is_package_current Is the installed version of a package current?
is_zero_matrix Is the input a zero matrix?
merge_dots_with_list Merge ellipsis args with a list.
is_qr Is the input a QR decomposition of a matrix?
is_leaf Is the input a (dendrogram) leaf?
is_xxx_for_decimal_point What does the current locale specify for the decimal point?
is_r_current Is this version of R up to date?
is_raster Is the input a raster?
is_raw Is the input raw?
use_first Only use the first element of a vector
safe_deparse Safe version of deparse
is_try_error Is the input a condition?
set_cause Set a cause and return the input
is_ts Is the input a time series?
is_uk_telephone_number Is the string a valid UK telephone number?
is_uk_car_licence Is the string a valid UK car licence plate number?
na NA, with a cause of failure
is_us_telephone_number Is the string a valid US telephone number?
is_us_social_security_number Is the string a valid US SSN?
n_elements Get the number of elements
strip_attributes Strip all attributes from a variable
sys_get_locale Get or set the system locale
parenthesize Wrap a string in brackets
print_and_capture Print a variable and capture the output
is_unsorted Is the input unsorted?
are_set_equal Set comparisons
Truth Is the input TRUE/FALSE/NA?
bapply Wrapper to vapply that returns booleans.
assert_is_all_of Does x belong to these classes?
assertive Readable check functions to ensure code integrity.
DIM Get the dimensions of an object
assert_engine Throws an error if a condition isn't met
are_identical Are the inputs identical?
are_same_length Are the inputs the same length/dimension?
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Vignettes of assertive

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Last month downloads


Type Package
Date 2020-07-30
License GPL (>= 3)
LazyLoad yes
LazyData yes
VignetteBuilder knitr
Acknowledgments Development of this package was partially funded by the Proteomics Core at Weill Cornell Medicine - Qatar . The Core is supported by 'Biomedical Research Program' funds, a program funded by Qatar Foundation.
RoxygenNote 7.1.1
NeedsCompilation no
Packaged 2020-07-31 18:29:39 UTC; richierocks
Repository CRAN
Date/Publication 2020-08-01 01:00:02 UTC

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