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https://github.com/eddelbuettel/rcppfastfloat

Rcpp Bindings for the 'fastfloat' Header-Only Library
https://github.com/eddelbuettel/rcppfastfloat

cran r r-package rcpp

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Rcpp Bindings for the 'fastfloat' Header-Only Library

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README 

        

## RcppFastFloat: Rcpp Bindings for the fastfloat C++ Header-Only Library



[![CI](https://github.com/eddelbuettel/rcppfastfloat/workflows/ci/badge.svg)](https://github.com/eddelbuettel/rcppfastfloat/actions?query=workflow%3Aci)

[![License](https://eddelbuettel.github.io/badges/GPL2+.svg)](https://www.gnu.org/licenses/gpl-2.0.html)

[![CRAN](https://www.r-pkg.org/badges/version/RcppFastFloat)](https://cran.r-project.org/package=RcppFastFloat)

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[![Downloads](https://cranlogs.r-pkg.org/badges/RcppFastFloat?color=brightgreen)](https://www.r-pkg.org/pkg/RcppFastFloat)

[![Last Commit](https://img.shields.io/github/last-commit/eddelbuettel/rcppfastfloat)](https://github.com/eddelbuettel/rcppfastfloat)



### Motivation



Converting ascii text into (floating-point) numeric values is a very common problem. The

[fast_float](https://github.com/fastfloat/fast_float) header-only C++ library by [Daniel

Lemire](https://lemire.me/en/) does this very well, and very fast at up to or over to 1 gigabyte per

second as described in more detail in a [recent arXiv paper](https://arxiv.org/abs/2101.11408).



This package brings this header-only library to R so that other R user can access it simply by

adding `LinkingTo: RcppFastFloat`.



### Example



A modified example function is included, try 



```r

library(RcppFastFloat)

exampleParse()

```



with default arguments---or supply some arguments.  We also include a simple timing comparison in

the file [benchmark/comparison.R](inst/benchmark/comparison.R) which you can run just call via

`Rscript` or [`r`](https://github.com/eddelbuettel/littler). On our machine, `fast_float` comes out

as just over 3 times as fast as the next best alternative (and this counts the function calls and

all, so pure parsing speed is still a little bettter).



```r

> source("comparison.R")

Unit: milliseconds

      expr      min       lq     mean   median       uq      max neval cld

     scanf 218.8936 224.1223 238.5650 227.1901 229.9116 1343.433   100   c

      atof 124.8087 127.3274 129.4104 128.5858 130.9138  146.334   100  b 

    strtod 124.5705 127.2157 129.1238 129.1042 130.7504  137.143   100  b 

      stod 127.1751 129.7343 131.7339 131.4854 133.1425  147.763   100  b 

 fastfloat  40.6219  41.3042  42.5729  42.3209  43.1738   57.788   100 a  

> 

```



Or in chart form:



![](https://eddelbuettel.github.io/rcppfastfloat/comparison.png)



### Status



Right now the package is brand new and reasonably empty. 



### Contributing



Any problems, bug reports, or features requests for the package can be submitted and handled most

conveniently as [Github issues](https://github.com/eddelbuettel/rcppfastfloat/issues) in the

repository.



Before submitting pull requests, it is frequently preferable to first discuss need and scope in such

an issue ticket.  See the file

[Contributing.md](https://github.com/RcppCore/Rcpp/blob/master/Contributing.md) (in the

[Rcpp](https://github.com/RcppCore/Rcpp) repo) for a brief discussion.



### Author



For the R package, [Dirk Eddelbuettel](https://github.com/eddelbuettel) and [Brendan

Knapp](https://github.com/knapply).



For everything pertaining to `fast_float`, [Daniel Lemire](https://lemire.me/en/) (and

[contributors](https://github.com/fastfloat/fast_float/graphs/contributors)).