| Title: | Framework to Marshal Objects to be Used in Another R Process |
|---|---|
| Description: | Some types of R objects can be used only in the R session they were created. If used as-is in another R process, such objects often result in an immediate error or in obscure and hard-to-troubleshoot outcomes. Because of this, they cannot be saved to file and re-used at a later time. They can also not be exported to a worker in parallel processing. These objects are sometimes referred to as non-exportable or non-serializable objects. One solution to this problem is to use "marshalling" to encode the R object into an exportable representation that then can be used to re-create a copy of that object in another R process. This package provides a framework for marshalling and unmarshalling R objects such that they can be transferred using functions such as serialize() and unserialize() of base R. |
| Authors: | Henrik Bengtsson [aut, cre, cph] |
| Maintainer: | Henrik Bengtsson <[email protected]> |
| License: | MIT + file LICENSE |
| Version: | 0.0.1 |
| Built: | 2024-10-27 05:52:37 UTC |
| Source: | https://github.com/futureverse/marshal |
Some types of R objects can be used only in the R session they were created. If used as-is in another R process, such objects often result in an immediate error or in obscure and hard-to-troubleshoot outcomes. Because of this, they cannot be saved to file and re-used at a later time. They can also not be exported to a worker in parallel processing. These objects are sometimes referred to as non-exportable or non-serializable objects. One solution to this problem is to use "marshalling" to encode the R object into an exportable representation that then can be used to re-create a copy of that object in another R process. This package provides a framework for marshalling and unmarshalling R objects such that they can be transferred using functions such as serialize() and unserialize() of base R.
Marshalling of R objects
marshal(...) unmarshal(...)marshal(...) unmarshal(...)
... |
The object to be marshalled, or unmarshalled, followed by additional arguments passed to the specific S3 method. |
marshal() returns a marshalled object, which is a list with
components:
marshalled: marshalled version of the original object
unmarshal: function that takes the marshalled object as
input and returns an unmarshalled version of the original object.
unmarshal() returns an unmarshalled version of the original object.
WARNING: This is very limited proof of concept!
## S3 method for class 'CFunc' marshal(inline, ...) ## S3 method for class 'CFunc' marshallable(...)## S3 method for class 'CFunc' marshal(inline, ...) ## S3 method for class 'CFunc' marshallable(...)
inline |
A CFunc function. |
... |
Not used. |
Currently, it is only possible to marshal a function:
of class CFunc that was created without "includes" or "otherdefs"
A marshalled object as described in marshal().
if (requireNamespace("inline", quietly = TRUE)) { code <- " int i; for (i = 0; i < *n; i++) x[0] = x[0] + (i+1); " sum_1_to_n <- inline::cfunction( signature(n = "integer", x = "numeric"), code, language = "C", convention = ".C" ) ## Marshal CFunc function sum_1_to_n_ <- marshal(sum_1_to_n) ## Unarshal CFunc function sum_1_to_n2 <- unmarshal(sum_1_to_n_) y <- sum_1_to_n(10, 0)$x print(y) y2 <- sum_1_to_n2(10, 0)$x print(y2) }if (requireNamespace("inline", quietly = TRUE)) { code <- " int i; for (i = 0; i < *n; i++) x[0] = x[0] + (i+1); " sum_1_to_n <- inline::cfunction( signature(n = "integer", x = "numeric"), code, language = "C", convention = ".C" ) ## Marshal CFunc function sum_1_to_n_ <- marshal(sum_1_to_n) ## Unarshal CFunc function sum_1_to_n2 <- unmarshal(sum_1_to_n_) y <- sum_1_to_n(10, 0)$x print(y) y2 <- sum_1_to_n2(10, 0)$x print(y2) }
Marshalling of R connections
## S3 method for class 'connection' marshal(con, ...) ## S3 method for class 'connection' marshallable(con, ...)## S3 method for class 'connection' marshal(con, ...) ## S3 method for class 'connection' marshallable(con, ...)
con |
A connection. |
... |
Not used. |
A marshalled object as described in marshal().
Not all connections can be marshalled, specifically we:
cannot marshal connections stdin (0), stdout (1), and stderr (2)
can only marshal read-only connections
can only marshal unopened or seekable connections
tf <- tempfile() cat(file = tf, letters, sep = "") ## Read-only connection con <- file(tf, open = "rb") bfr <- readChar(con, nchars = 4L) print(bfr) ## "abcd" ## Marshal read-only connection, which records the ## current state, including the current file position. con_ <- marshal(con) ## Unmarshal connection, which restores the state ## of the original connection, including the current ## file position con2 <- unmarshal(con_) stopifnot( all.equal(summary(con2), summary(con)), identical(seek(con2), seek(con)) ) bfr <- readChar(con, nchars = 4L) print(bfr) bfr2 <- readChar(con2, nchars = 4L) print(bfr2) stopifnot(identical(bfr2, bfr)) ## Cleanup close(con) close(con2) file.remove(tf) con <- url("https://www.r-project.org") print(con) ## Marshal read-only connection, which records the ## current state, including the current file position. con_ <- marshal(con) ## Unmarshal connection, which restores the state ## of the original connection con2 <- unmarshal(con_) print(con2) stopifnot(all.equal(summary(con2), summary(con))) bfr <- readChar(con, nchars = 100L) print(bfr) bfr2 <- readChar(con2, nchars = 100L) print(bfr2) stopifnot(identical(bfr2, bfr)) ## Cleanup close(con) close(con2)tf <- tempfile() cat(file = tf, letters, sep = "") ## Read-only connection con <- file(tf, open = "rb") bfr <- readChar(con, nchars = 4L) print(bfr) ## "abcd" ## Marshal read-only connection, which records the ## current state, including the current file position. con_ <- marshal(con) ## Unmarshal connection, which restores the state ## of the original connection, including the current ## file position con2 <- unmarshal(con_) stopifnot( all.equal(summary(con2), summary(con)), identical(seek(con2), seek(con)) ) bfr <- readChar(con, nchars = 4L) print(bfr) bfr2 <- readChar(con2, nchars = 4L) print(bfr2) stopifnot(identical(bfr2, bfr)) ## Cleanup close(con) close(con2) file.remove(tf) con <- url("https://www.r-project.org") print(con) ## Marshal read-only connection, which records the ## current state, including the current file position. con_ <- marshal(con) ## Unmarshal connection, which restores the state ## of the original connection con2 <- unmarshal(con_) print(con2) stopifnot(all.equal(summary(con2), summary(con))) bfr <- readChar(con, nchars = 100L) print(bfr) bfr2 <- readChar(con2, nchars = 100L) print(bfr2) stopifnot(identical(bfr2, bfr)) ## Cleanup close(con) close(con2)
Marshalling of 'data.table' objects
## S3 method for class 'data.table' marshal(x, ...) ## S3 method for class 'data.table' marshallable(...)## S3 method for class 'data.table' marshal(x, ...) ## S3 method for class 'data.table' marshallable(...)
x |
A data.table::data.table object. |
... |
Not used. |
A marshalled object as described in marshal().
if (requireNamespace("data.table", quietly = TRUE)) { dt <- data.table::data.table(a = 1:3, b = letters[1:3]) ## Marshal dt_ <- marshal(dt) ## Unmarshal dt2 <- unmarshal(dt_) stopifnot(identical(dt2, dt)) ## Marshal and unmarshal again dt2_ <- marshal(dt2) dt3 <- unmarshal(dt2_) stopifnot( identical(dt2_, dt_), identical(dt3, dt2) ) }if (requireNamespace("data.table", quietly = TRUE)) { dt <- data.table::data.table(a = 1:3, b = letters[1:3]) ## Marshal dt_ <- marshal(dt) ## Unmarshal dt2 <- unmarshal(dt_) stopifnot(identical(dt2, dt)) ## Marshal and unmarshal again dt2_ <- marshal(dt2) dt3 <- unmarshal(dt2_) stopifnot( identical(dt2_, dt_), identical(dt3, dt2) ) }
Warning: Objects of this class are not possible to marshal. If attempted, an error is produced.
## S3 method for class 'DBIConnection' marshal(x, ...) ## S3 method for class 'DBIConnection' marshallable(...)## S3 method for class 'DBIConnection' marshal(x, ...) ## S3 method for class 'DBIConnection' marshallable(...)
x |
A DBI::DBIConnection object. |
... |
Not used. |
A marshalled object as described in marshal().
Marshalling of 'h2o' objects
## S3 method for class 'H2OAutoML' marshal(x, ...) ## S3 method for class 'H2OMultinomialModel' marshal(x, ...) ## S3 method for class 'H2OBinomialModel' marshal(x, ...) ## S3 method for class 'H2ORegressionModel' marshal(x, ...) ## S3 method for class 'H2OAutoML' marshallable(...) ## S3 method for class 'H2OMultinomialModel' marshallable(...) ## S3 method for class 'H2OBinomialModel' marshallable(...) ## S3 method for class 'H2ORegressionModel' marshallable(...)## S3 method for class 'H2OAutoML' marshal(x, ...) ## S3 method for class 'H2OMultinomialModel' marshal(x, ...) ## S3 method for class 'H2OBinomialModel' marshal(x, ...) ## S3 method for class 'H2ORegressionModel' marshal(x, ...) ## S3 method for class 'H2OAutoML' marshallable(...) ## S3 method for class 'H2OMultinomialModel' marshallable(...) ## S3 method for class 'H2OBinomialModel' marshallable(...) ## S3 method for class 'H2ORegressionModel' marshallable(...)
x |
An "h2o" object. |
... |
Not used. |
h2o::h2o.save_mojo() and h2o::h2o.saveModel() are used to produce
a marshalled version of the original object.
h2o::h2o.import_mojo() and h2o::h2o.loadModel() are used to
reconstruct a version of the original object from the marshalled object.
A marshalled object as described in marshal().
Warning: Objects of this class are not possible to marshal. If attempted, an error is produced.
## S3 method for class 'jclassName' marshal(x, ...) ## S3 method for class 'jobjRef' marshal(x, ...) ## S3 method for class 'jclassName' marshallable(...) ## S3 method for class 'jobjRef' marshallable(...)## S3 method for class 'jclassName' marshal(x, ...) ## S3 method for class 'jobjRef' marshal(x, ...) ## S3 method for class 'jclassName' marshallable(...) ## S3 method for class 'jobjRef' marshallable(...)
x |
"rJava" object. |
... |
Not used. |
A marshalled object as described in marshal().
Marshalling of 'keras' objects
## S3 method for class 'keras.engine.base_layer.Layer' marshal(model, ...) ## S3 method for class 'keras.engine.base_layer.Layer' marshallable(...)## S3 method for class 'keras.engine.base_layer.Layer' marshal(model, ...) ## S3 method for class 'keras.engine.base_layer.Layer' marshallable(...)
model |
A keras:keras.engine.base_layer.Layer object. |
... |
Not used. |
keras::serialize_model() is used to produce a marshalled version
of the original object.
keras::unserialize_model() is used to reconstruct a version of the
original object from the marshalled object.
A marshalled object as described in marshal().
## Run only in interactive mode, because example takes > 5 seconds, ## which is longer than what is allowed on CRAN if (interactive() && requireNamespace("keras", quietly = TRUE)) { library(keras) ## Create a keras model (adopted from {keras} vignette) inputs <- layer_input(shape = shape(32)) outputs <- layer_dense(inputs, units = 1L) model <- keras_model(inputs, outputs) model <- compile(model, optimizer = "adam", loss = "mean_squared_error") print(model) ## Not needed anymore rm(list = c("inputs", "outputs")) ## Marshal model_ <- marshal(model) ## Unmarshal model2 <- unmarshal(model_) stopifnot( identical(summary(model2), summary(model)) ) ## Fitted keras model (adopted from {keras} vignette) test_input <- array(runif(128 * 32), dim = c(128, 32)) test_target <- array(runif(128), dim = c(128, 1)) hist <- fit(model, test_input, test_target) print(hist) print(model) ## Not needed anymore rm(list = "test_target") ## Marshal model_ <- marshal(model) ## Unmarshal model2 <- unmarshal(model_) stopifnot( identical(summary(model2), summary(model)), identical(stats::predict(model2, test_input), stats::predict(model, test_input)) ) }## Run only in interactive mode, because example takes > 5 seconds, ## which is longer than what is allowed on CRAN if (interactive() && requireNamespace("keras", quietly = TRUE)) { library(keras) ## Create a keras model (adopted from {keras} vignette) inputs <- layer_input(shape = shape(32)) outputs <- layer_dense(inputs, units = 1L) model <- keras_model(inputs, outputs) model <- compile(model, optimizer = "adam", loss = "mean_squared_error") print(model) ## Not needed anymore rm(list = c("inputs", "outputs")) ## Marshal model_ <- marshal(model) ## Unmarshal model2 <- unmarshal(model_) stopifnot( identical(summary(model2), summary(model)) ) ## Fitted keras model (adopted from {keras} vignette) test_input <- array(runif(128 * 32), dim = c(128, 32)) test_target <- array(runif(128), dim = c(128, 1)) hist <- fit(model, test_input, test_target) print(hist) print(model) ## Not needed anymore rm(list = "test_target") ## Marshal model_ <- marshal(model) ## Unmarshal model2 <- unmarshal(model_) stopifnot( identical(summary(model2), summary(model)), identical(stats::predict(model2, test_input), stats::predict(model, test_input)) ) }
Marshalling of 'torch' objects
## S3 method for class 'luz_module_fitted' marshal(model, ...) ## S3 method for class 'luz_module_fitted' marshallable(...)## S3 method for class 'luz_module_fitted' marshal(model, ...) ## S3 method for class 'luz_module_fitted' marshallable(...)
model |
A |
... |
Not used. |
luz::luz_save() is used to produce a marshalled version
of the original object.
luz::luz_load() is used to reconstruct a version of the
original object from the marshalled object.
A marshalled object as described in marshal().
Warning: Objects of this class are not possible to marshal. If attempted, an error is produced.
## S3 method for class ''magick-image'' marshal(x, ...) ## S3 method for class ''magick-image'' marshallable(...)## S3 method for class ''magick-image'' marshal(x, ...) ## S3 method for class ''magick-image'' marshallable(...)
x |
A magick:magick-image object. |
... |
Not used. |
A marshalled object as described in marshal().
Marshalling of 'parsnip' objects
## S3 method for class 'model_fit' marshal(x, ...) ## S3 method for class 'model_fit' marshallable(...)## S3 method for class 'model_fit' marshal(x, ...) ## S3 method for class 'model_fit' marshallable(...)
x |
A |
... |
Not used. |
The fit element of the model_fit object is marshalled.
A marshalled object as described in marshal().
if (requireNamespace("parsnip", quietly = TRUE) && requireNamespace("xgboost", quietly = TRUE)) { library(parsnip) ## Adopted from example("boost_tree", package = "parsnip") model <- boost_tree(mode = "classification", trees = 20L, engine = "xgboost") model <- set_mode(model, "regression") fit <- fit(model, mpg ~ ., data = datasets::mtcars) ## Marshal fit_ <- marshal(fit) ## Unmarshal fit2 <- unmarshal(fit_) ## Marshal again fit2_ <- marshal(fit2) ## Assert identity stopifnot( all.equal(fit2_, fit_) ) fit3 <- unmarshal(fit2_) ## Assert identity stopifnot( all.equal(fit3, fit2) ) }if (requireNamespace("parsnip", quietly = TRUE) && requireNamespace("xgboost", quietly = TRUE)) { library(parsnip) ## Adopted from example("boost_tree", package = "parsnip") model <- boost_tree(mode = "classification", trees = 20L, engine = "xgboost") model <- set_mode(model, "regression") fit <- fit(model, mpg ~ ., data = datasets::mtcars) ## Marshal fit_ <- marshal(fit) ## Unmarshal fit2 <- unmarshal(fit_) ## Marshal again fit2_ <- marshal(fit2) ## Assert identity stopifnot( all.equal(fit2_, fit_) ) fit3 <- unmarshal(fit2_) ## Assert identity stopifnot( all.equal(fit3, fit2) ) }
Marshalling of 'ncdf4' objects
## S3 method for class 'ncdf4' marshal(x, ...) ## S3 method for class 'ncdf4' marshallable(...)## S3 method for class 'ncdf4' marshal(x, ...) ## S3 method for class 'ncdf4' marshallable(...)
x |
A ncdf4:ncdf4 object. |
... |
Not used. |
base::readBin() is used to produce a marshalled version
of the original object.
base::writeBin() and ncdf4::nc_open() are used to
reconstruct a version of the original object from the
marshalled object.
A marshalled object as described in marshal().
if (requireNamespace("ncdf4", quietly = TRUE)) { library(ncdf4) ## Create a temporary NCDF file tf <- tempfile(fileext = ".nc") x <- ncvar_def("x", units = "count", dim = list()) nf <- nc_create(tf, x) ncvar_put(nf, x, 42) print(nf) nc_close(nf) rm(list = c("nf", "x")) ## Open NCDF file nf <- nc_open(tf) y <- ncvar_get(nf, "x") ## Marshal nf_ <- marshal(nf) ## Unmarshal nf2 <- unmarshal(nf_) y2 <- ncvar_get(nf2, "x") stopifnot(identical(y2, y)) }if (requireNamespace("ncdf4", quietly = TRUE)) { library(ncdf4) ## Create a temporary NCDF file tf <- tempfile(fileext = ".nc") x <- ncvar_def("x", units = "count", dim = list()) nf <- nc_create(tf, x) ncvar_put(nf, x, 42) print(nf) nc_close(nf) rm(list = c("nf", "x")) ## Open NCDF file nf <- nc_open(tf) y <- ncvar_get(nf, "x") ## Marshal nf_ <- marshal(nf) ## Unmarshal nf2 <- unmarshal(nf_) y2 <- ncvar_get(nf2, "x") stopifnot(identical(y2, y)) }
Warning: Objects of this class are not possible to marshal. If attempted, an error is produced.
## S3 method for class 'python.builtin.object' marshal(x, ...) ## S3 method for class 'python.builtin.object' marshallable(...)## S3 method for class 'python.builtin.object' marshal(x, ...) ## S3 method for class 'python.builtin.object' marshallable(...)
x |
"reticulate" object. |
... |
Not used. |
A marshalled object as described in marshal().
Marshalling of 'raster' objects
## S3 method for class 'RasterLayer' marshal(x, ...) ## S3 method for class 'RasterLayer' marshallable(x, ...)## S3 method for class 'RasterLayer' marshal(x, ...) ## S3 method for class 'RasterLayer' marshallable(x, ...)
x |
A raster:RasterLayer object. |
... |
Not used. |
raster::writeRaster() is used to produce a marshalled version
of the original object.
raster::raster() is used to reconstruct a version of the
original object from the marshalled object.
A marshalled object as described in marshal().
Marshalling of RasterLayer objects is leaky. More precisely,
the method cannot guarantee that multiple rounds of marshalling
and unmarshalling produce numerically identical objects.
if (requireNamespace("raster", quietly = TRUE)) { r <- raster::raster(system.file("external/test.grd", package = "raster")) print(r) ## Marshal r_ <- marshal(r) ## Unmarshal r2 <- unmarshal(r_) print(r2) }if (requireNamespace("raster", quietly = TRUE)) { r <- raster::raster(system.file("external/test.grd", package = "raster")) print(r) ## Marshal r_ <- marshal(r) ## Unmarshal r2 <- unmarshal(r_) print(r2) }
Warning: Objects of this class are not possible to marshal. If attempted, an error is produced.
## S3 method for class 'SOCKcluster' marshal(x, ...) ## S3 method for class 'SOCKnode' marshal(x, ...) ## S3 method for class 'SOCK0node' marshal(x, ...) ## S3 method for class 'SOCKcluster' marshallable(...) ## S3 method for class 'SOCKnode' marshallable(...) ## S3 method for class 'SOCK0node' marshallable(...)## S3 method for class 'SOCKcluster' marshal(x, ...) ## S3 method for class 'SOCKnode' marshal(x, ...) ## S3 method for class 'SOCK0node' marshal(x, ...) ## S3 method for class 'SOCKcluster' marshallable(...) ## S3 method for class 'SOCKnode' marshallable(...) ## S3 method for class 'SOCK0node' marshallable(...)
x |
A magick:magick-image object. |
... |
Not used. |
A marshalled object as described in marshal().
Marshalling of 'terra' objects
## S3 method for class 'SpatVector' marshal(terra, ...) ## S3 method for class 'SpatVector' marshallable(...)## S3 method for class 'SpatVector' marshal(terra, ...) ## S3 method for class 'SpatVector' marshallable(...)
terra |
|
... |
Not used. |
terra::wrap() is used to produce a marshalled version
of the original object.
terra::vect() is used to reconstruct a version of the
original object from the marshalled object.
A marshalled object as described in marshal().
if (requireNamespace("terra", quietly = TRUE)) { file <- system.file("ex/lux.shp", package = "terra") v <- terra::vect(file) ## Marshal SpatVector object v_ <- marshal(v) ## Unmarshal SpatVector object v2 <- unmarshal(v_) stopifnot(all.equal(v2, v, check.attributes = FALSE)) }if (requireNamespace("terra", quietly = TRUE)) { file <- system.file("ex/lux.shp", package = "terra") v <- terra::vect(file) ## Marshal SpatVector object v_ <- marshal(v) ## Unmarshal SpatVector object v2 <- unmarshal(v_) stopifnot(all.equal(v2, v, check.attributes = FALSE)) }
Marshalling of 'rstan' objects
## S3 method for class 'stanfit' marshal(x, ...) ## S3 method for class 'stanfit' marshallable(...)## S3 method for class 'stanfit' marshal(x, ...) ## S3 method for class 'stanfit' marshallable(...)
x |
A |
... |
Not used. |
A marshalled object as described in marshal().
Warning: Objects of this class are not possible to marshal. If attempted, an error is produced.
## S3 method for class 'tbl_spark' marshal(x, ...) ## S3 method for class 'tbl_spark' marshallable(...)## S3 method for class 'tbl_spark' marshal(x, ...) ## S3 method for class 'tbl_spark' marshallable(...)
x |
"sparklyr" object. |
... |
Not used. |
A marshalled object as described in marshal().
Marshalling of 'caret:train' objects
## S3 method for class 'train' marshal(train, ...) ## S3 method for class 'train' marshallable(...)## S3 method for class 'train' marshal(train, ...) ## S3 method for class 'train' marshallable(...)
train |
A caret::train object. |
... |
Not used. |
bundle::bundle() is used to produce a marshalled version
of the original object.
bundle::unbundle() is used to reconstruct a version of the
original object from the marshalled object.
A marshalled object as described in marshal().
Warning: Objects of this class are not possible to marshal. If attempted, an error is produced.
## S3 method for class 'udpipe_model' marshal(x, ...) ## S3 method for class 'udpipe_model' marshallable(...)## S3 method for class 'udpipe_model' marshal(x, ...) ## S3 method for class 'udpipe_model' marshallable(...)
x |
"udpipe" object. |
... |
Not used. |
A marshalled object as described in marshal().
Marshalling of 'xgboost' objects
## S3 method for class 'xgb.DMatrix' marshal(x, ...) ## S3 method for class 'xgb.Booster' marshal(x, ...) ## S3 method for class 'xgb.Booster' marshallable(...) ## S3 method for class 'xgb.DMatrix' marshallable(...)## S3 method for class 'xgb.DMatrix' marshal(x, ...) ## S3 method for class 'xgb.Booster' marshal(x, ...) ## S3 method for class 'xgb.Booster' marshallable(...) ## S3 method for class 'xgb.DMatrix' marshallable(...)
x |
An xgboost::xgb.DMatrix or an |
... |
Not used. |
xgboost::xgb.DMatrix.save() is used to produce a marshalled version
of the original object.
xgboost::xgb.DMatrix() is used to reconstruct a version of the
original object from the marshalled object.
A marshalled object as described in marshal().
Marshalling of 'xml2' objects
## S3 method for class 'xml_document' marshal(xml2, ...) ## S3 method for class 'xml_nodeset' marshal(xml2, ...) ## S3 method for class 'xml_document' marshallable(...) ## S3 method for class 'xml_nodeset' marshallable(...)## S3 method for class 'xml_document' marshal(xml2, ...) ## S3 method for class 'xml_nodeset' marshal(xml2, ...) ## S3 method for class 'xml_document' marshallable(...) ## S3 method for class 'xml_nodeset' marshallable(...)
xml2 |
A xml2::xml_document or similar. |
... |
Not used. |
xml2::xml_serialize() is used to produce a marshalled version
of the original object.
xml2::xml_unserialize() is used to reconstruct a version of the
original object from the marshalled object.
A marshalled object as described in marshal().
if (requireNamespace("xml2", quietly = TRUE)) { doc <- xml2::read_xml("<body></body>") ## Marshal 'xml_document' object doc_ <- marshal(doc) ## Unmarshal 'xml_document' object doc2 <- unmarshal(doc_) stopifnot(all.equal(doc2, doc)) }if (requireNamespace("xml2", quietly = TRUE)) { doc <- xml2::read_xml("<body></body>") ## Marshal 'xml_document' object doc_ <- marshal(doc) ## Unmarshal 'xml_document' object doc2 <- unmarshal(doc_) stopifnot(all.equal(doc2, doc)) }
Marshalling of 'XML' objects
## S3 method for class 'XMLAbstractNode' marshal(xml, ...) ## S3 method for class 'XMLAbstractDocument' marshal(xml, ...) ## S3 method for class 'XMLAbstractDocument' marshallable(...) ## S3 method for class 'XMLAbstractNode' marshallable(...)## S3 method for class 'XMLAbstractNode' marshal(xml, ...) ## S3 method for class 'XMLAbstractDocument' marshal(xml, ...) ## S3 method for class 'XMLAbstractDocument' marshallable(...) ## S3 method for class 'XMLAbstractNode' marshallable(...)
xml |
|
... |
Not used. |
XML::xmlSerializeHook() is used to produce a marshalled version
of the original object.
XML::xmlDeserializeHook() is used to reconstruct a version of the
original object from the marshalled object.
A marshalled object as described in marshal().
if (requireNamespace("XML", quietly = TRUE)) { node <- XML::xmlParseString("<a><b>c</b></a>") print(node) ## Marshal XMLAbstractNode object node_ <- marshal(node) ## Unmarshal XMLAbstractNode object node2 <- unmarshal(node_) print(node2) stopifnot(all.equal(node2, node)) doc <- XML::xmlParse(system.file("exampleData", "tides.xml", package = "XML")) ## Marshal XMLAbstractDocument object doc_ <- marshal(doc) ## Unmarshal XMLAbstractDocument object doc2 <- unmarshal(doc_) stopifnot(all.equal(doc2, doc)) }if (requireNamespace("XML", quietly = TRUE)) { node <- XML::xmlParseString("<a><b>c</b></a>") print(node) ## Marshal XMLAbstractNode object node_ <- marshal(node) ## Unmarshal XMLAbstractNode object node2 <- unmarshal(node_) print(node2) stopifnot(all.equal(node2, node)) doc <- XML::xmlParse(system.file("exampleData", "tides.xml", package = "XML")) ## Marshal XMLAbstractDocument object doc_ <- marshal(doc) ## Unmarshal XMLAbstractDocument object doc2 <- unmarshal(doc_) stopifnot(all.equal(doc2, doc)) }
Check if R object can be marshalled
marshallable(...)marshallable(...)
... |
The object to be checked, followed by additional arguments passed to the specific S3 method. |
TRUE if the object can be marshalled,
FALSE if it cannot be marshalled, and
NA if it is not known whether the object can be marshalled.