Parameter File (`data.inp`)

emout reads the EMSES parameter file (plasma.inp or plasma.toml) and exposes it as a dictionary-like object with attribute access.

Accessing Parameters

import emout

data = emout.Emout("output_dir")

# Dictionary-style access with group name
data.inp["tmgrid"]["nx"]    # → e.g., 256
data.inp["plasma"]["wp"]    # → e.g., [1.0, 0.05]

# Group name can be omitted if the parameter name is unambiguous
data.inp["nx"]              # → same as data.inp["tmgrid"]["nx"]

# Attribute-style access
data.inp.tmgrid.nx
data.inp.nx                 # Group name omitted

Commonly Used Parameters

Grid

Parameter	Group	Description
`nx`, `ny`, `nz`	`tmgrid`	Grid dimensions
`dx`, `dy`, `dz`	`tmgrid`	Grid spacing (in EMSES units; see `data.unit.length` for SI)

nx, ny, nz = data.inp.nx, data.inp.ny, data.inp.nz

Time

Parameter	Group	Description
`dt`	`tmgrid`	Time step
`ifdiag`	`tmgrid`	Output interval (every `ifdiag` steps)
`nstep`	`tmgrid`	Total number of steps

dt = data.inp.dt
total_time_steps = data.inp.nstep
output_interval = data.inp.ifdiag

Plasma

Parameter	Group	Description
`nspec`	`plasma`	Number of particle species
`wp`	`plasma`	Plasma frequency per species
`qm`	`plasma`	Charge-to-mass ratio per species
`path`	`plasma`	Thermal velocity per species
`peth`	`plasma`	Thermal velocity (alternative)

nspec = data.inp.nspec
wp = data.inp.wp        # list of plasma frequencies
qm = data.inp.qm        # list of charge-to-mass ratios

Boundaries

Parameter	Group	Description
`mtd_vbnd`	`emissn`	Boundary type per axis (0=periodic, 1=Dirichlet, 2=Neumann)

btypes = data.inp.mtd_vbnd  # e.g., [0, 2, 0] for periodic-Neumann-periodic

TOML Format (`plasma.toml`)

When plasma.toml exists, emout automatically runs toml2inp to generate plasma.inp, then loads it. The toml2inp command is bundled with MPIEMSES3D.

data = emout.Emout("output_dir")
data.inp.nx          # Same interface regardless of file format

Accessing Raw TOML Structure

Use data.toml for direct access to the native TOML structure:

data.toml                        # TomlData wrapper (None if plasma.inp only)
data.toml.tmgrid.nx              # attribute access
data.toml["tmgrid"]["nx"]        # dict-style access
data.toml.species[0].wp          # nested structures

The TOML format uses section headers corresponding to namelist groups:

[tmgrid]
nx = 256
ny = 256
nz = 512
dt = 0.5

[[species]]
wp = 1.0
qm = -1.0

[[species]]
wp = 0.05
qm = 0.001

Separating Input and Output

data = emout.Emout(input_path="/path/to/plasma.toml", output_directory="output_dir")

Unit Conversion Key

The first line of plasma.inp may contain a unit conversion key:

!!key dx=[0.5],to_c=[10000.0]

dx: Grid spacing in meters [m]
to_c: Speed of light in EMSES internal units

This key enables SI unit conversion via data.unit. In plasma.toml, this is expressed as:

[meta.unit_conversion]
dx = 0.5
to_c = 10000.0

If no conversion key is present, data.unit will be None and SI features (val_si, use_si=True) will fall back to raw EMSES units.

Parameter File (data.inp)