Simple properties¶

Contents

Property functions
Basic properties
Basic selectors
Basic mathematical functions
Basic statistical functions
SGChem properties
Sink particle properties
Sink particle selectors

Property functions ¶

Simple properties are directly taken or derived from the snapshot properties.

Every property called <NAME> is defined as:

prop_<NAME>(ids, ptype, **prop)

Parameters

ids (list[bool]) – Particle IDs selectors
ptype (int) – Particle type
prop (dict) – Dictionary with additional properties

In the class descriptions below we will list only additional parameters included in the prop dictionary.

Basic properties ¶

class arepy.files.prop.simple¶

Simple properties

Properties in this class can be extracted directly from the Arepo snapshot.

prop_ParticleIDs(ids, ptype, **prop)¶

Get cell IDs

Returns: Array with particle IDs
Return type: list[int]

prop_Masses(ids, ptype, **prop)¶

Get cell masses

Returns: Array of particle masses
Return type: list[float]

prop_Density(ids, ptype, **prop)¶

Get cell densities

Returns: Array of particle densities
Return type: list[float]

prop_InternalEnergy(ids, ptype, **prop)¶

Get cell internal energies

Returns: Array of particle internal energies
Return type: list[float]

prop_Coordinates(ids, ptype, **prop)¶

Get cell coordinates

Returns: Array of particle coordinates
Return type: list[[float]*3]

prop_PosX(ids, ptype, **prop)¶

Get cell x coordinates

Returns: Array of particle x coordinates
Return type: list[float]

prop_PosY(ids, ptype, **prop)¶

Get cell y coordinates

Returns: Array of particle y coordinates
Return type: list[float]

prop_PosZ(ids, ptype, **prop)¶

Get cell z coordinates

Returns: Array of particle z coordinates
Return type: list[float]

prop_Velocities(ids, ptype, **prop)¶

Get cell velocities

Returns: Array of particle velocities
Return type: list[[float]*3]

prop_VelX(ids, ptype, **prop)¶

Get cell x velocities

Returns: Array of particle x velocities
Return type: list[float]

prop_VelY(ids, ptype, **prop)¶

Get cell y velocities

Returns: Array of particle y velocities
Return type: list[float]

prop_VelZ(ids, ptype, **prop)¶

Get cell z velocities

Returns: Array of particle z velocities
Return type: list[float]

prop_FileIndex(ids, ptype, **prop)¶: Index of a file where the particle is saved

prop_ParticleIndex(ids, ptype, **prop)¶: Index of a particle within the dataset

prop_Radius(ids, ptype, **prop)¶

Get radius distances from a given center point

Parameters: center ([int,int,int]) – Center point coordinates
Returns: Cell distances from the center
Return type: list[int]

prop_Radius2(ids, ptype, **prop)¶

Square of a particle radius from a given center

Parameters: center ([int,int,int]) – Center point coordinates
Returns: Square of a radius from the center
Return type: list[int]

prop_VelocityRadial(ids, ptype, **prop)¶

Radial component of the velocities

Parameters: center ([float]*3) – Point from which the velocity component is calculated
Return [float]*3: Radial velocity component size

Calculation of the component is taken from Wikipedia.

\[v_\perp = v . \hat{n}\]

prop_VelocitySphere(ids, ptype, **prop)¶

Cell velocitie vectors in spherical coordinates with respect to a center

Parameters: center ([float]*3) – Point from which the velocity components are calculated
Return [float]*2: Radial and tangential velocity components

Calculation of the components is take from Wikipedia.

prop_CellVolume(ids, ptype, **prop)¶

Particle cell Volume

Return float: Cell volume

Volume of the cell is calculated from its mass and density:

\[V = \frac{M}{\rho}\]

prop_CellRadius(ids, ptype, **prop)¶

Particle cell mean radius

Return float: Mean cell radius

Cell radius is only approximated from the cell volume:

\[r = \left( \frac{3V}{4\pi} \right)^{1/3}\]

Basic selectors ¶

class arepy.files.prop.simpleSelect¶

Simple selections

These function return selection indexes according to different selection criteria.

Examples:

Return selection together with other properties:

>>> particleIDs = [20234939, 42394849, 2384784,...]
>>> snap.getProperty([
>>>      'ParticleIDs',
>>>      {'name':'SelectIds', 'pids': particleIDs}
>>> ])

{'ParticleIDs': [20234939, 5234234, 94588239,...],
 'SelectIds': [True, False, False, ...]}

Return selection only:

>>> particleIDs = [20234939, 42394849, 2384784,...]
>>> snap.getProperty({'name':'SelectIds', 'pids': particleIDs})

[True, False, False, ...]

prop_SelectIds(ids, ptype, **prop)¶

Select cells with particular IDs

Parameters: pids (list[int]) – Particle IDs
Returns: Selection indexes of the selected particles
Return type: list[int]

Note

For large numbers of IDs this can get quite slow, because it uses numpy.in1d() function.

prop_SelectSphere(ids, ptype, **prop)¶

Select cells from a spherical region

Parameters

radius (float) – Sphere radius
center ([float]*3) – Sphere center

Returns

Selection indexes of the selected particles

Return type

list[int]

prop_SelectBox(ids, ptype, **prop)¶

Select cells from a box

Parameters: center ([float]*6) – Box limits (xmin,xmax,ymin,ymax,zmin,zmax)
Returns: Selection indexes of the selected particles
Return type: list[int]

prop_SelectPoints(ids, ptype, **prop)¶

Select cells closest to the given points

Parameters: coord (list[[float]*3]) – List of coordinates
Returns: Selection indexes of the selected particles
Return type: list[int]

prop_Indexes(ids, ptype, **prop)¶

Get current selector indexes

Returns: Array with selector indexes
Return type: list[bool]

Basic mathematical functions ¶

class arepy.files.prop.simpleMath¶

Simple mathematical operation

The properties in this class perform simple mathematical operations with the snapshot data

prop_MathPlus(ids, ptype, **prop)¶: Addition of two datasets

prop_MathMinus(ids, ptype, **prop)¶: Substraction of two datasets

prop_MathMultiply(ids, ptype, **prop)¶: Multiplication of two datasets

prop_MathDivide(ids, ptype, **prop)¶: Division of two datasets

prop_MathModulo(ids, ptype, **prop)¶: Modulo of two datasets

Basic statistical functions ¶

class arepy.files.prop.simpleStat¶

Simple statistics

The properties in this class perform simple statistical operations on the snapshot data.

prop_StatMinimum(ids, ptype, **prop)¶: Minimum value of a property

prop_StatMinPos(ids, ptype, **prop)¶: Minimum positive value of a property

prop_StatMaximum(ids, ptype, **prop)¶: Maximum value of a property

prop_StatMean(ids, ptype, **prop)¶: Mean value of a property

prop_StatSum(ids, ptype, **prop)¶: Sum of values of a property

prop_Hist1D(ids, ptype, **prop)¶: Histogram of a single property

prop_Hist2D(ids, ptype, **prop)¶: Histogram of two properties

SGChem properties ¶

class arepy.files.prop.sgchem1¶

SGChem properties

Chemistry specific properties that can be used only with the primordial chemistry module SGChem.

prop_ChemicalAbundances(ids, ptype, **prop)¶

Chemical abundances

Returns: List of chemical abundances
Return type: list[float]*9

prop_x_H2(ids, ptype, **prop)¶

Abundance of a molecular Hydrogen

Returns: List of H2 abundances
Return type: list[float]

prop_x_HP(ids, ptype, **prop)¶

Abundance of a ionized Hydrogen

Returns: List of H+ abundances
Return type: list[float]

prop_x_DP(ids, ptype, **prop)¶

Abundance of a ionized Deuterium

Returns: List of D+ abundances
Return type: list[float]

prop_Gamma(ids, ptype, **prop)¶

Polytropic index

Returns: If value of Gamma is not present in a snapshot this returns a standard value of Gamma=5/3

Sink particle properties ¶

class arepy.files.prop.sink¶

Properties of the sink particle file

Propertis in this class are extracted from the sink particle snapshot files. Therefore, they are accessible only if the sink particle snapshot are available. It is possible to call sink snapshot properties when particle type is set to ptype=5.

prop_SinkFormationOrder(ids, ptype, **prop)¶

Returns value of the sink formation order

Returns: Formation order of sink particles
Return type: list[int]

prop_SinkFormationTime(ids, ptype, **prop)¶

Returns value of the sink formation time

Returns: Formation time of sink particles
Return type: list[float]

prop_SinkID(ids, ptype, **prop)¶

Returns value of the sink IDs

Returns: Particle IDs of sink particles
Return type: list[int]

prop_SinkMass(ids, ptype, **prop)¶

Returns value of the sink masses

Returns: Masses of sink particles
Return type: list[float]

prop_SinkAccretionRate(ids, ptype, **prop)¶

Returns value of the sink accretion rate

Returns: Accretion rate of sink particles
Return type: list[float]

Sink particle selectors ¶

class arepy.files.prop.sinkSelect¶

Sink particle selectors

Selector function specific for the sink particle properties only accessible in the sink particle snapshot.

prop_SelectFormationOrder(ids, ptype, **prop)¶

Selecting particles with a given formation order values

Parameters: forder (list[int]) – List of formation order values
Returns: Particle selection indexes
Return type: list[bool]

Simple properties¶

Property functions ¶

Basic properties ¶

Basic selectors ¶

Basic mathematical functions ¶

Basic statistical functions ¶

SGChem properties ¶

Sink particle properties ¶

Sink particle selectors ¶

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