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The new `constants`

package is available on CRAN. This small package provides the CODATA 2014 internationally recommended values of the fundamental physical constants (universal, electromagnetic, physicochemical, atomic…), provided as symbols for direct use within the R language. Optionally, the values with errors and/or the values with units are also provided if the `errors`

and/or the `units`

packages are installed as well.

But, what is CODATA? The Committee on Data for Science and Technology (CODATA) is an interdisciplinary committee of the International Council for Science. The Task Group on Fundamental Constants periodically provides the internationally accepted set of values of the fundamental physical constants. The version currently in force is the “2014 CODATA”, published on 25 June 2015.

This package wraps the `codata`

dataset, defines unique symbols for each one of the 237 constants, and provides them enclosed in three sets of symbols: `syms`

, `syms_with_errors`

and `syms_with_units`

.

```
library(constants)
# the speed of light
with(syms, c0)
```

`## [1] 299792458`

```
# explore which constants are available
lookup("planck constant", ignore.case=TRUE)
```

```
## quantity symbol value unit
## 7 Planck constant h 6.626070040e-34 J s
## 8 Planck constant h_eV 4.135667662e-15 eV s
## 9 Planck constant hbar h/(2*pi) J s
## 10 Planck constant hbar_eV h_eV/(2*pi) eV s
## 11 Planck constant hbar.c0 197.3269788 MeV fm
## 212 molar Planck constant Na.h 3.9903127110e-10 J s mol-1
## 213 molar Planck constant Na.h.c0 0.119626565582 J m mol-1
## rel_uncertainty type
## 7 1.2e-08 universal
## 8 6.1e-09 universal
## 9 1.2e-08 universal
## 10 6.1e-09 universal
## 11 6.1e-09 universal
## 212 4.5e-10 physicochemical
## 213 4.5e-10 physicochemical
```

```
# symbols can also be attached to the search path
attach(syms)
# the Planck constant
hbar
```

`## [1] 1.054572e-34`

If the `errors`

/`units`

package is installed in your system, constants with errors/units are available:

```
attach(syms_with_errors)
# the Planck constant with error
hbar
```

`## 1.05457180(1)e-34`

```
attach(syms_with_units)
# the Planck constant with units
hbar
```

`## 1.054572e-34 J*s`

The dataset is available for lazy loading:

```
data(codata)
head(codata)
```

```
## quantity symbol value unit
## 1 speed of light in vacuum c0 299792458 m s-1
## 2 magnetic constant mu0 4*pi*1e-7 N A-2
## 3 electric constant epsilon0 1/(mu0*c0^2) F m-1
## 4 characteristic impedance of vacuum Z0 mu0*c0 Ω
## 5 Newtonian constant of gravitation G 6.67408e-11 m3 kg-1 s-2
## 6 Newtonian constant of gravitation G_hbar.c0 6.70861e-39 GeV-2 c4
## rel_uncertainty type
## 1 0.0e+00 universal
## 2 0.0e+00 universal
## 3 0.0e+00 universal
## 4 0.0e+00 universal
## 5 4.7e-05 universal
## 6 4.7e-05 universal
```

`dplyr::count(codata, type, sort=TRUE)`

```
## # A tibble: 15 x 2
## type n
##
```
## 1 atomic-nuclear-electron 31
## 2 atomic-nuclear-proton 26
## 3 atomic-nuclear-neutron 24
## 4 physicochemical 24
## 5 atomic-nuclear-helion 18
## 6 atomic-nuclear-muon 17
## 7 electromagnetic 17
## 8 universal 16
## 9 atomic-nuclear-deuteron 15
## 10 atomic-nuclear-general 11
## 11 atomic-nuclear-tau 11
## 12 atomic-nuclear-triton 11
## 13 adopted 7
## 14 atomic-nuclear-alpha 7
## 15 atomic-nuclear-electroweak 2

*Article originally published in Enchufa2.es: constants 0.0.1*.

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