This function allows the user to browse directly on any of the
currently active function calls, and is suitable as an error option.
options(error = recover) will make this
the error option.
recover prints the list of current calls, and
prompts the user to select one of them. The standard R
browser is then invoked from the corresponding
environment; the user can type ordinary R language expressions to be
evaluated in that environment.
When finished browsing in this call, type
c to return to
recover from the browser. Type another frame number to browse
some more, or type
0 to exit
The use of
recover largely supersedes
as an error option, unless you really want to wait to look at the
recover is called in non-interactive mode, it
dump.frames. For computations involving large
amounts of data,
recover has the advantage that it does not
need to copy out all the environments in order to browse in them. If
you do decide to quit interactive debugging, call
dump.frames directly while browsing in any frame (see
Nothing useful is returned. However, you can invoke
recover directly from a function, rather than through the error
option shown in the examples. In this case, execution continues
after you type
0 to exit
recover function can be used in the same way as the
S function of the same name; therefore, the error option shown is
a compatible way to specify the error action. However, the actual
functions are essentially unrelated and interact quite differently
with the user. The navigating commands
not exist in the R version; instead, exit the browser and select
John M. Chambers (1998).
Programming with Data; Springer.
See the compatibility note above, however.
browser for details about the interactive computations;
options for setting the error option;
dump.frames to save the current environments for later
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## Not run: options(error = recover) # setting the error option ### Example of interaction > myFit <- lm(y ~ x, data = xy, weights = w) Error in lm.wfit(x, y, w, offset = offset, ...) : missing or negative weights not allowed Enter a frame number, or 0 to exit 1:lm(y ~ x, data = xy, weights = w) 2:lm.wfit(x, y, w, offset = offset, ...) Selection: 2 Called from: eval(expr, envir, enclos) Browse> objects() # all the objects in this frame  "method" "n" "ny" "offset" "tol" "w"  "x" "y" Browse> w  -0.5013844 1.3112515 0.2939348 -0.8983705 -0.1538642  -0.9772989 0.7888790 -0.1919154 -0.3026882 Browse> dump.frames() # save for offline debugging Browse> c # exit the browser Enter a frame number, or 0 to exit 1:lm(y ~ x, data = xy, weights = w) 2:lm.wfit(x, y, w, offset = offset, ...) Selection: 0 # exit recover > ## End(Not run)