Jeroen Ooms

A new version of
[jsonlite](https://cran.r-project.org/web/packages/jsonlite/index.html)
package to CRAN. This is a maintenance release with enhancements and bug
fixes. A summary of changes in v1.2 from the
[NEWS](https://cran.r-project.org/web/packages/jsonlite/NEWS) file:

- Add `read_json` and `write_json` convenience wrappers,
  [\#161](https://github.com/jeroen/jsonlite/issues/161)
- Update `modp_numtoa` from upstream, fixes a rounding issue in
  [\#148](https://github.com/jeroen/jsonlite/issues/148).
- Ensure `asJSON.POSIXt` does not use sci notation for negative values,
  [\#155](https://github.com/jeroen/jsonlite/issues/155)
- Tweak `num_to_char` to properly print large negative numbers
- Performance optimization for simplyfing data frames (see below)

Use the *Github compare* page to see the full diff on
[metacran](https://github.com/cran/jsonlite/compare/1.1...1.2).

## New read/write API

The package has gained new high level functions `read_json` and
`write_json`. These are
[wrappers](https://github.com/cran/jsonlite/blob/1.2/R/read_json.R#L18-L29)
for `fromJSON` and `toJSON` which read/write json directly from/to disk.
This API is consistent with tidyverse packages like readr, readxl and
haven (see [\#161](https://github.com/jeroen/jsonlite/issues/161)).

The only thing to note is that `read_json` does not simplify by default,
as is done by `fromJSON`. For example:

::: {.highlight}
``` {.chroma tabindex="0"}
# Write Data frame to a temp filetmp <- tempfile()write_json(iris, tmp)# Nested listsread_json(tmp)# A data frameread_json(tmp, simplifyVector = TRUE)
```
:::

Notice how `read_json` only returns a data frame when `simplifyVector`
is explicitly set to `TRUE`.

## Performance enhancements

We have ported a bit of C code to optimize simplification for data frame
structures. This script compares performance for both versions:

::: {.highlight}
``` {.chroma tabindex="0"}
# example jsonjson <- jsonlite::toJSON(ggplot2::diamonds)# Test with jsonlite 1.1devtools::install_github("cran/jsonlite@1.1")microbenchmark::microbenchmark(jsonlite::fromJSON(json), times = 50)# Unload jsonlite 1.1 (might need restart R on windows)unloadNamespace("jsonlite")library.dynam.unload('jsonlite', find.package('jsonlite'))# Test with jsonlite 1.2devtools::install_github("cran/jsonlite@1.2")microbenchmark::microbenchmark(jsonlite::fromJSON(json), times = 50)
```
:::

On my Macbook this has reduced the median time from approx 0.91s to
0.76s.


A new version of jsonlite package to CRAN. This is a maintenance release with enhancements and bug fixes. A summary of changes in v1.2 from the NEWS file: Add read_json and write_json convenience wrappers, #161 Update modp_numtoa from upstream, fixes a rounding issue in #148.

Messaggi di Rogue Scholar

Update jsonlite 1.2