prv: Output variable states within functions/loops during...

In NCmisc: Miscellaneous Functions for Creating Adaptive Functions and Scripts

Output variable states within functions/loops during testing/debugging

Description

Same as preview but no labels command, and input is without quotes and should be plain variable names of existing variables (no indices, args, etc) A versatile function to compactly display most common R objects. Will return the object name, type, dimension, and a compact representation of object contents, for instance using prv.large() to display matrices, so as to not overload the console for large objects. Useful for debugging, can be placed inside loops and functions to track values, dimensions, and data types. Particularly when debugging complex code, the automatic display of the variable name prevents confusion versus using regular print statements. By listing variables to track as character(), provides 'cat()' output of compact and informative variable state information, e.g, variable name, value, datatype and dimension. Can also specify array or list elements, or custom labels. prv() is the same as preview() except it can take objects without using double quotes and has no 'labels' command (and doesn't need one). If expressions are entered rather than variable names, then prv() will attempt to pass the arguments to preview(). prv() assumes that the variable(s) to report originate from the environment calling prv(), and if not found there, then it will search through all accessible environments starting with the global environment, and then will report the first instance found, which in exceptional circumstances (be warned) may not be the instance you intended to retrieve.

Usage

prv(..., counts = NULL)

Arguments

...	series of variable(s) to report, separated by commas, which will trigger automatic labelling of the variable name
counts	a list of array index values; so if calling during a counting loop, the value can be reported each iteration, also printing the count index; if the list is named the name will also appear, e.g, variable[count=1]. This list must be the same length as the variable list ... , and each element [[i]] must contain as many values as the original corresponding variable list[i] has dimensions

See Also

Dim

Examples

# create variables of different types to show output styles #
testvar1 <- 193
testvar2 <- "Atol"
testvar3 <- c(1:10)
testvar4 <- matrix(rnorm(100),nrow=25)
testvar5 <- list(first="test",second=testvar4,third=100:110)
preview("testvar1"); prv(testvar1)
prv(testvar1,testvar2,testvar3,testvar4)
prv(matrix(rnorm(100),nrow=25)) # expression sent to preview() with no label
prv(193) # fails as there are no object names involved

NCmisc documentation built on Oct. 17, 2022, 5:09 p.m.