Hi Axel, You can assign new symbols as well. It sounds like you want to do this for a number of datasets, so you could define new symbols and add them to yt’s unit registry (though you could also add them to a specific dataset’s unit registry). To do the former, you could do something like this in your plugins [1] file (which would ensure they got loaded every time you used yt): ```python from yt.units.unit_object import default_unit_registry from yt.units import dimensions default_unit_registry.add("lambda_0", 8.0e-5, dimensions.length, 0.0, r"$\lambda_0$") default_unit_registry.add("omega_pe", 1.0e15, dimensions.rate, 0.0, r"$\omega_\text{pe}$") ``` The arguments in .add are the name of the symbol, the conversion to CGS+Ampere, the dimensions of the unit, the unit offset (only used for temperature and angle units), and the last is the LaTeX representation. Note that I defined omega_pe as a rate, so you’d have to use its inverse when creating your unit system to define the base time units. And yes, as I mentioned above the internal base by which all yt units reference is cgs units + Amperes for current (for historical reasons, mostly). Best, John [1] http://yt-project.org/doc/reference/configuration.html#the-plugin-file http://yt-project.org/doc/reference/configuration.html#the-plugin-file

On Jan 5, 2017, at 8:24 AM, Axel Huebl wrote:

Ha, I oversaw a link in [1] linking to [2].

Ok, so I can just specify my own unit system in user-code with that. But anyhow, I can't assign it new symbols. Also, do all conversion factors need to go through CGS?

Also, microns turns out to be .in_units("um") :)

Axel

[2] http://yt-project.org/docs/dev/analyzing/units/unit_systems.html

On 05.01.2017 13:59, Axel Huebl wrote:

...

Hi yt-devs!

I have a quick user-question (sorry) and a devel question:

First, how to convert to a unit like microns (10^-6 meters) or pico-seconds? I can't find an example here [1]. I tried

.in_units("mum") .in_units("mu m) .in_units("1.e-6 m") .in_units("microns") .in_units("micro meter") .in_units("micro meters") .in_units("micro m") .in_units("μm")

and only .in_units("1.e-6 * m")

does not fail but looks ugly.

An orthogonal question: in our domain (laser-plasma physics) unit systems are scaled by something like the applied laser wavelength or the plasma density (and more to make a full set).

Following again [1] I would implement something like .in_base('plasma') or .in_base('laserplasma') but those are not scaled to "fixed" reference quantities as the other base systems but are depending on either user input [ length = ("$\lambda_0$", "800 nm"), time = ("$\omega_\text{pe}^{-1}$", "1.e-15 s"), ...] or alternatively scalings the data file already provided. (Ok, the symbol is always fixed per "in_base" but the value to scale with needs to be provided.)

Is that already possible or any ideas how we could implement that?

Thanks, Axel

[1] http://yt-project.org/docs/dev/analyzing/units/fields_and_unit_conversion.ht...

--

Axel Huebl Phone +49 351 260 3582 https://www.hzdr.de/crp Computational Radiation Physics Laser Particle Acceleration Division Helmholtz-Zentrum Dresden - Rossendorf e.V.

Bautzner Landstrasse 400, 01328 Dresden POB 510119, D-01314 Dresden Vorstand: Prof. Dr.Dr.h.c. R. Sauerbrey Prof. Dr.Dr.h.c. P. Joehnk VR 1693 beim Amtsgericht Dresden _______________________________________________ yt-dev mailing list yt-dev@lists.spacepope.org http://lists.spacepope.org/listinfo.cgi/yt-dev-spacepope.org

Yeah, I was thinking that as I was writing it.

On Jan 5, 2017, at 8:57 AM, Nathan Goldbaum wrote:

We should have a nicer API for this. Something like astropy's def_unit:

http://docs.astropy.org/en/stable/api/astropy.units.def_unit.html#astropy.un... http://docs.astropy.org/en/stable/api/astropy.units.def_unit.html#astropy.un...

On Thu, Jan 5, 2017 at 7:48 AM John ZuHone mailto:jzuhone@gmail.com> wrote: Hi Axel,

You can assign new symbols as well. It sounds like you want to do this for a number of datasets, so you could define new symbols and add them to yt’s unit registry (though you could also add them to a specific dataset’s unit registry). To do the former, you could do something like this in your plugins [1] file (which would ensure they got loaded every time you used yt):

```python from yt.units.unit_object import default_unit_registry from yt.units import dimensions

default_unit_registry.add("lambda_0", 8.0e-5, dimensions.length, 0.0, r"$\lambda_0$") default_unit_registry.add("omega_pe", 1.0e15, dimensions.rate, 0.0, r"$\omega_\text{pe}$") ```

The arguments in .add are the name of the symbol, the conversion to CGS+Ampere, the dimensions of the unit, the unit offset (only used for temperature and angle units), and the last is the LaTeX representation.

Note that I defined omega_pe as a rate, so you’d have to use its inverse when creating your unit system to define the base time units.

And yes, as I mentioned above the internal base by which all yt units reference is cgs units + Amperes for current (for historical reasons, mostly).

Best,

John

[1] http://yt-project.org/doc/reference/configuration.html#the-plugin-file http://yt-project.org/doc/reference/configuration.html#the-plugin-file

...

On Jan 5, 2017, at 8:24 AM, Axel Huebl mailto:a.huebl@hzdr.de> wrote:

Ha, I oversaw a link in [1] linking to [2].

Ok, so I can just specify my own unit system in user-code with that. But anyhow, I can't assign it new symbols. Also, do all conversion factors need to go through CGS?

Also, microns turns out to be .in_units("um") :)

Axel

[2] http://yt-project.org/docs/dev/analyzing/units/unit_systems.html http://yt-project.org/docs/dev/analyzing/units/unit_systems.html

On 05.01.2017 13:59, Axel Huebl wrote:

...

Hi yt-devs!

I have a quick user-question (sorry) and a devel question:

First, how to convert to a unit like microns (10^-6 meters) or pico-seconds? I can't find an example here [1]. I tried

.in_units("mum") .in_units("mu m) .in_units("1.e-6 m") .in_units("microns") .in_units("micro meter") .in_units("micro meters") .in_units("micro m") .in_units("μm")

and only .in_units("1.e-6 * m")

does not fail but looks ugly.

An orthogonal question: in our domain (laser-plasma physics) unit systems are scaled by something like the applied laser wavelength or the plasma density (and more to make a full set).

Following again [1] I would implement something like .in_base('plasma') or .in_base('laserplasma') but those are not scaled to "fixed" reference quantities as the other base systems but are depending on either user input [ length = ("$\lambda_0$", "800 nm"), time = ("$\omega_\text{pe}^{-1}$", "1.e-15 s"), ...] or alternatively scalings the data file already provided. (Ok, the symbol is always fixed per "in_base" but the value to scale with needs to be provided.)

Is that already possible or any ideas how we could implement that?

Thanks, Axel

[1] http://yt-project.org/docs/dev/analyzing/units/fields_and_unit_conversion.ht... http://yt-project.org/docs/dev/analyzing/units/fields_and_unit_conversion.ht...

--

Axel Huebl Phone +49 351 260 3582 https://www.hzdr.de/crp https://www.hzdr.de/crp Computational Radiation Physics Laser Particle Acceleration Division Helmholtz-Zentrum Dresden - Rossendorf e.V.

Bautzner Landstrasse 400, 01328 Dresden POB 510119, D-01314 Dresden Vorstand: Prof. Dr.Dr.h.c. R. Sauerbrey Prof. Dr.Dr.h.c. P. Joehnk VR 1693 beim Amtsgericht Dresden _______________________________________________ yt-dev mailing list yt-dev@lists.spacepope.org mailto:yt-dev@lists.spacepope.org http://lists.spacepope.org/listinfo.cgi/yt-dev-spacepope.org http://lists.spacepope.org/listinfo.cgi/yt-dev-spacepope.org

_______________________________________________

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yt-dev@lists.spacepope.org mailto:yt-dev@lists.spacepope.org

http://lists.spacepope.org/listinfo.cgi/yt-dev-spacepope.org http://lists.spacepope.org/listinfo.cgi/yt-dev-spacepope.org

_______________________________________________ yt-dev mailing list yt-dev@lists.spacepope.org http://lists.spacepope.org/listinfo.cgi/yt-dev-spacepope.org

John went ahead and implemented this: https://bitbucket.org/yt_analysis/yt/pull-requests/2485/ Thanks John! On Thu, Jan 5, 2017 at 9:47 AM Axel Huebl wrote:

Thanks for the quick responses, I will try that tomorrow! :)

On 05.01.2017 15:23, John ZuHone wrote:

...

Yeah, I was thinking that as I was writing it.

...

...

...

On Jan 5, 2017, at 8:57 AM, Nathan Goldbaum

...

...

mailto:nathan12343@gmail.com> wrote:

...

...

...

...

We should have a nicer API for this. Something like astropy's def_unit:

...

...

...

...

http://docs.astropy.org/en/stable/api/astropy.units.def_unit.html#astropy.un...

...

...

...

...

On Thu, Jan 5, 2017 at 7:48 AM John ZuHone

...

...

mailto:jzuhone@gmail.com> wrote:

...

...

...

...

Hi Axel,

...

...

...

...

You can assign new symbols as well. It sounds like you want to do

...

...

this for a number of datasets, so you could define new symbols and

...

...

add them to yt’s unit registry (though you could also add them to

...

...

a specific dataset’s unit registry). To do the former, you could

...

...

do something like this in your plugins [1] file (which would

...

...

ensure they got loaded every time you used yt):

...

...

...

...

```python

...

...

from yt.units.unit_object import default_unit_registry

...

...

from yt.units import dimensions

...

...

...

...

default_unit_registry.add("lambda_0", 8.0e-5, dimensions.length,

...

...

0.0, r"$\lambda_0$")

...

...

default_unit_registry.add("omega_pe", 1.0e15, dimensions.rate,

...

...

0.0, r"$\omega_\text{pe}$")

...

...

```

...

...

...

...

The arguments in .add are the name of the symbol, the conversion

...

...

to CGS+Ampere, the dimensions of the unit, the unit offset (only

...

...

used for temperature and angle units), and the last is the LaTeX

...

...

representation.

...

...

...

...

Note that I defined omega_pe as a rate, so you’d have to use its

...

...

inverse when creating your unit system to define the base time

units.

...

...

...

...

And yes, as I mentioned above the internal base by which all yt

...

...

units reference is cgs units + Amperes for current (for historical

...

...

reasons, mostly).

...

...

...

...

Best,

...

...

...

...

John

...

...

...

...

[1]

http://yt-project.org/doc/reference/configuration.html#the-plugin-file

...

...

...

...

...

On Jan 5, 2017, at 8:24 AM, Axel Huebl

...

...

...

mailto:a.huebl@hzdr.de> wrote:

...

...

...

...

...

...

Ha, I oversaw a link in [1] linking to [2].

...

...

...

...

...

...

Ok, so I can just specify my own unit system in user-code with

that.

...

...

...

But anyhow, I can't assign it new symbols. Also, do all conversion

...

...

...

factors need to go through CGS?

...

...

...

...

...

...

Also, microns turns out to be

...

...

...

.in_units("um")

...

...

...

:)

...

...

...

...

...

...

...

...

...

Axel

...

...

...

...

...

...

[2]

http://yt-project.org/docs/dev/analyzing/units/unit_systems.html

...

...

...

...

...

...

On 05.01.2017 13:59, Axel Huebl wrote:

...

...

...

...

Hi yt-devs!

...

...

...

...

...

...

...

...

I have a quick user-question (sorry) and a devel question:

...

...

...

...

...

...

...

...

First, how to convert to a unit like microns (10^-6 meters) or

...

...

...

...

pico-seconds? I can't find an example here [1]. I tried

...

...

...

...

...

...

...

...

.in_units("mum")

...

...

...

...

.in_units("mu m)

...

...

...

...

.in_units("1.e-6 m")

...

...

...

...

.in_units("microns")

...

...

...

...

.in_units("micro meter")

...

...

...

...

.in_units("micro meters")

...

...

...

...

.in_units("micro m")

...

...

...

...

.in_units("μm")

...

...

...

...

...

...

...

...

and only

...

...

...

...

.in_units("1.e-6 * m")

...

...

...

...

...

...

...

...

does not fail but looks ugly.

...

...

...

...

...

...

...

...

An orthogonal question: in our domain (laser-plasma physics) unit

...

...

...

...

systems are scaled by something like the applied laser

...

...

...

...

wavelength or the

...

...

...

...

plasma density (and more to make a full set).

...

...

...

...

...

...

...

...

Following again [1] I would implement something like

...

...

...

...

.in_base('plasma')

...

...

...

...

or .in_base('laserplasma') but those are not scaled to "fixed"

...

...

...

...

reference

...

...

...

...

quantities as the other base systems but are depending on either

...

...

...

...

user input

...

...

...

...

[ length = ("$\lambda_0$", "800 nm"),

...

...

...

...

time = ("$\omega_\text{pe}^{-1}$", "1.e-15 s"),

...

...

...

...

...]

...

...

...

...

or alternatively scalings the data file already provided. (Ok, the

...

...

...

...

symbol is always fixed per "in_base" but the value to scale with

...

...

...

...

needs

...

...

...

...

to be provided.)

...

...

...

...

...

...

...

...

Is that already possible or any ideas how we could implement that?

...

...

...

...

...

...

...

...

...

...

...

...

Thanks,

...

...

...

...

Axel

...

...

...

...

...

...

...

...

[1]

...

...

...

...

http://yt-project.org/docs/dev/analyzing/units/fields_and_unit_conversion.ht...

...

...

...

...

...

...

...

...

...

...

--

...

...

...

...

...

...

Axel Huebl

...

...

...

Phone +49 351 260 3582

...

...

...

https://www.hzdr.de/crp

...

...

...

Computational Radiation Physics

...

...

...

Laser Particle Acceleration Division

...

...

...

Helmholtz-Zentrum Dresden - Rossendorf e.V.

...

...

...

...

...

...

Bautzner Landstrasse 400, 01328 Dresden

...

...

...

POB 510119, D-01314 Dresden

...

...

...

Vorstand: Prof. Dr.Dr.h.c. R. Sauerbrey

...

...

...

Prof. Dr.Dr.h.c. P. Joehnk

...

...

...

VR 1693 beim Amtsgericht Dresden

...

...

...

_______________________________________________

...

...

...

yt-dev mailing list

...

...

...

yt-dev@lists.spacepope.org mailto:yt-dev@lists.spacepope.org

...

...

...

http://lists.spacepope.org/listinfo.cgi/yt-dev-spacepope.org

...

...

...

...

_______________________________________________

...

...

...

...

yt-dev mailing list

...

...

...

...

yt-dev@lists.spacepope.org mailto:yt-dev@lists.spacepope.org

...

...

...

...

http://lists.spacepope.org/listinfo.cgi/yt-dev-spacepope.org

...

...

...

...

_______________________________________________

...

...

yt-dev mailing list

...

...

yt-dev@lists.spacepope.org mailto:yt-dev@lists.spacepope.org

...

...

http://lists.spacepope.org/listinfo.cgi/yt-dev-spacepope.org

...

...

...

...

_______________________________________________

...

yt-dev mailing list

...

yt-dev@lists.spacepope.org

...

http://lists.spacepope.org/listinfo.cgi/yt-dev-spacepope.org

...

--

Axel Huebl

Phone +49 351 260 3582

https://www.hzdr.de/crp

Computational Radiation Physics

Laser Particle Acceleration Division

Helmholtz-Zentrum Dresden - Rossendorf e.V.

Bautzner Landstrasse 400, 01328 Dresden

POB 510119, D-01314 Dresden

Vorstand: Prof. Dr.Dr.h.c. R. Sauerbrey

Prof. Dr.Dr.h.c. P. Joehnk

VR 1693 beim Amtsgericht Dresden

_______________________________________________

yt-dev mailing list

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