Register LaTeX reader for Cosmology

@Mubin17

What is the problem this feature will solve?

A reader for the Cosmology -> LaTeX (-> Cosmology)

Describe the desired outcome

No response

Additional context

Following up on #14701, thanks @Mubin17!

@Mubin17

@Mubin17, right of refusal is yours 😆.

We usually don't milestone issues. Will this block 6.0 release or something?

Not strictly, but it should be in by then. I want read/write for LaTeX by 6.0.

@nstarman

@nstarman Before I create a PR. While working on write_latex(), I came up with the following code for read_latex() based on the structure of read_html_table():

def read_latex(filename, index=None, *, move_to_meta=False, cosmology=None,**kwargs):
    format = kwargs.pop("format", "latex")
    if format != "latex":
        raise ValueError(f"format must be 'latex', not {format}")
    
    with u.add_enabled_units(cu):
        table = QTable.read(filename, format="latex", **kwargs)

    table_columns = set(table.colnames)
    for name, latex in _FORMAT_TABLE.items():
        if latex in table_columns:
            table.rename_column(latex, name)
            
    # Build the cosmology from table, using the private backend.
    return from_table(table, index=index, move_to_meta=move_to_meta, cosmology=cosmology)

However, upon execution, it throws this error:

ValueError: '.. 0.06' did not parse as unit: Syntax error parsing unit '.. 0.06' 
If this is meant to be a custom unit, define it with 'u.def_unit'. 
To have it recognized inside a file reader or other code, enable it with 'u.add_enabled_units'. 
For details, see https://docs.astropy.org/en/latest/units/combining_and_defining.html

Do you have any suggestions on how can I tackle this error?

Do you recall which line is throwing this error? Is it table = QTable.read(filename, format="latex", **kwargs)?

@nstarman

@nstarman I believe it is the following line return from_table(table, index=index, move_to_meta=move_to_meta, cosmology=cosmology). For further clarification I have put the entire error message below:

ValueError                                Traceback (most recent call last)
File ~/opt/anaconda3/envs/Astropy_Playground/lib/python3.10/site-packages/astropy/units/format/generic.py:613, in Generic._do_parse(cls, s, debug)
    610 try:
    611     # This is a short circuit for the case where the string
    612     # is just a single unit name
--> 613     return cls._parse_unit(s, detailed_exception=False)
    614 except ValueError as e:

File ~/opt/anaconda3/envs/Astropy_Playground/lib/python3.10/site-packages/astropy/units/format/generic.py:512, in 
Generic._parse_unit(cls, s, detailed_exception)
    511 else:
--> 512     raise ValueError()

ValueError: 

During handling of the above exception, another exception occurred:

ValueError                                Traceback (most recent call last)
File ~/opt/anaconda3/envs/Astropy_Playground/lib/python3.10/site-packages/astropy/units/format/generic.py:616, in 
Generic._do_parse(cls, s, debug)
    615 try:
--> 616     return cls._parser.parse(s, lexer=cls._lexer, debug=debug)
    617 except ValueError as e:

File ~/opt/anaconda3/envs/Astropy_Playground/lib/python3.10/site-packages/astropy/utils/parsing.py:115, in 
ThreadSafeParser.parse(self, *args, **kwargs)
    114 with self._lock:
--> 115     return self.parser.parse(*args, **kwargs)

File ~/opt/anaconda3/envs/Astropy_Playground/lib/python3.10/site-packages/astropy/extern/ply/yacc.py:333, in 
LRParser.parse(self, input, lexer, debug, tracking, tokenfunc)
    332 else:
--> 333     return self.parseopt_notrack(input, lexer, debug, tracking, tokenfunc)

File ~/opt/anaconda3/envs/Astropy_Playground/lib/python3.10/site-packages/astropy/extern/ply/yacc.py:1201, in 
LRParser.parseopt_notrack(self, input, lexer, debug, tracking, tokenfunc)
   1200 self.state = state
-> 1201 tok = call_errorfunc(self.errorfunc, errtoken, self)
   1202 if self.errorok:
   1203     # User must have done some kind of panic
   1204     # mode recovery on their own.  The
   1205     # returned token is the next lookahead

File ~/opt/anaconda3/envs/Astropy_Playground/lib/python3.10/site-packages/astropy/extern/ply/yacc.py:192, in 
call_errorfunc(errorfunc, token, parser)
    191 _restart = parser.restart
--> 192 r = errorfunc(token)
    193 try:

File ~/opt/anaconda3/envs/Astropy_Playground/lib/python3.10/site-packages/astropy/units/format/generic.py:473, in 
Generic._make_parser.<locals>.p_error(p)
    472 def p_error(p):
--> 473     raise ValueError()

ValueError: 

During handling of the above exception, another exception occurred:

ValueError                                Traceback (most recent call last)
File ~/opt/anaconda3/envs/Astropy_Playground/lib/python3.10/site-packages/astropy/units/core.py:2018, in 
_UnitMetaClass.__call__(self, s, represents, format, namespace, doc, parse_strict)
   2017 try:
-> 2018     return f.parse(s)
   2019 except NotImplementedError:

File ~/opt/anaconda3/envs/Astropy_Playground/lib/python3.10/site-packages/astropy/units/format/generic.py:598, in 
Generic.parse(cls, s, debug)
    596     s = cls._regex_deg.sub(cls._convert_deg, s)
--> 598 result = cls._do_parse(s, debug=debug)
    599 # Check for excess solidi, but exclude fractional exponents (accepted)

File ~/opt/anaconda3/envs/Astropy_Playground/lib/python3.10/site-packages/astropy/units/format/generic.py:621, in 
Generic._do_parse(cls, s, debug)
    620 else:
--> 621     raise ValueError(f"Syntax error parsing unit '{s}'")

ValueError: Syntax error parsing unit '.. 0.06'

During handling of the above exception, another exception occurred:

ValueError                                Traceback (most recent call last)
Cell In[4], line 1
----> 1 Cosmology.read("example_cosmology.tex",index=1, format="latex")

File ~/opt/anaconda3/envs/Astropy_Playground/lib/python3.10/site-packages/astropy/cosmology/connect.py:81, in 
CosmologyRead.__call__(self, *args, **kwargs)
     76         raise ValueError(
     77             "keyword argument `cosmology` must be either the class "
     78             f"{valid[0]} or its qualified name '{valid[1]}'")
     80 with add_enabled_units(cu):
---> 81     cosmo = self.registry.read(self._cls, *args, **kwargs)
     83 return cosmo

File ~/opt/anaconda3/envs/Astropy_Playground/lib/python3.10/site-packages/astropy/io/registry/core.py:212, in 
UnifiedInputRegistry.read(self, cls, format, cache, *args, **kwargs)
    208     format = self._get_valid_format(
    209         'read', cls, path, fileobj, args, kwargs)
    211 reader = self.get_reader(format, cls)
--> 212 data = reader(*args, **kwargs)
    214 if not isinstance(data, cls):
    215     # User has read with a subclass where only the parent class is
    216     # registered.  This returns the parent class, so try coercing
    217     # to desired subclass.
    218     try:

File ~/opt/anaconda3/envs/Astropy_Playground/lib/python3.10/site-packages/astropy/cosmology/io/latex.py:41, in 
read_latex(filename, index, move_to_meta, cosmology, **kwargs)
     38         table.rename_column(latex, name)
     40 # Build the cosmology from table, using the private backend.
---> 41 return from_table(table, index=index, move_to_meta=move_to_meta, cosmology=cosmology)

File ~/opt/anaconda3/envs/Astropy_Playground/lib/python3.10/site-packages/astropy/cosmology/io/table.py:136, in 
from_table(table, index, move_to_meta, cosmology)
    133 row = table[index]  # index is now the row index (int)
    135 # parse row to cosmo
--> 136 return from_row(row, move_to_meta=move_to_meta, cosmology=cosmology)

File ~/opt/anaconda3/envs/Astropy_Playground/lib/python3.10/site-packages/astropy/cosmology/io/row.py:80, in 
from_row(row, move_to_meta, cosmology)
     77 mapping["meta"] = dict(meta)
     79 # build cosmology from map
---> 80 return from_mapping(mapping, move_to_meta=move_to_meta, cosmology=cosmology)

File ~/opt/anaconda3/envs/Astropy_Playground/lib/python3.10/site-packages/astropy/cosmology/io/mapping.py:114, in 
from_mapping(map, move_to_meta, cosmology)
    111     raise TypeError(f"there are unused parameters {params}.")
    112 # else: pass  # no kwargs, no move-to-meta, and all the params are used
--> 114 return cosmology(*ba.args, **ba.kwargs)

File ~/opt/anaconda3/envs/Astropy_Playground/lib/python3.10/site-packages/astropy/cosmology/flrw/lambdacdm.py:616, in
 FlatLambdaCDM.__init__(self, H0, Om0, Tcmb0, Neff, m_nu, Ob0, name, meta)
    614 def __init__(self, H0, Om0, Tcmb0=0.0*u.K, Neff=3.04, m_nu=0.0*u.eV,
    615              Ob0=None, *, name=None, meta=None):
--> 616     super().__init__(H0=H0, Om0=Om0, Ode0=0.0, Tcmb0=Tcmb0, Neff=Neff,
    617                      m_nu=m_nu, Ob0=Ob0, name=name, meta=meta)
    619     # Please see :ref:`astropy-cosmology-fast-integrals` for discussion
    620     # about what is being done here.
    621     if self._Tcmb0.value == 0:

File ~/opt/anaconda3/envs/Astropy_Playground/lib/python3.10/site-packages/astropy/cosmology/flrw/base.py:1434, in 
FlatFLRWMixin.__init__(self, *args, **kw)
   1433 def __init__(self, *args, **kw):
-> 1434     super().__init__(*args, **kw)  # guaranteed not to have `Ode0`
   1435     # Do some twiddling after the fact to get flatness
   1436     self._Ok0 = 0.0

File ~/opt/anaconda3/envs/Astropy_Playground/lib/python3.10/site-packages/astropy/cosmology/flrw/lambdacdm.py:91, in LambdaCDM.__init__(self, H0, Om0, Ode0, Tcmb0, Neff, m_nu, Ob0, name, meta)
     89 def __init__(self, H0, Om0, Ode0, Tcmb0=0.0*u.K, Neff=3.04, m_nu=0.0*u.eV,
     90              Ob0=None, *, name=None, meta=None):
---> 91     super().__init__(H0=H0, Om0=Om0, Ode0=Ode0, Tcmb0=Tcmb0, Neff=Neff,
     92                      m_nu=m_nu, Ob0=Ob0, name=name, meta=meta)
     94     # Please see :ref:`astropy-cosmology-fast-integrals` for discussion
     95     # about what is being done here.
     96     if self._Tcmb0.value == 0:

File ~/opt/anaconda3/envs/Astropy_Playground/lib/python3.10/site-packages/astropy/cosmology/flrw/base.py:144, in FLRW.__init__(self, H0, Om0, Ode0, Tcmb0, Neff, m_nu, Ob0, name, meta)
    142 self.Tcmb0 = Tcmb0
    143 self.Neff = Neff
--> 144 self.m_nu = m_nu  # (reset later, this is just for unit validation)
    145 self.Ob0 = Ob0  # (must be after Om0)
    147 # Derived quantities:
    148 # Dark matter density; matter - baryons, if latter is not None.

File ~/opt/anaconda3/envs/Astropy_Playground/lib/python3.10/site-packages/astropy/cosmology/parameter.py:128, in Parameter.__set__(self, cosmology, value)
    125     raise AttributeError(f"can't set attribute {self._attr_name} again")
    127 # Validate value, generally setting units if present
--> 128 value = self.validate(cosmology, copy.deepcopy(value))
    130 # Make the value read-only, if ndarray-like
    131 if hasattr(value, "setflags"):

File ~/opt/anaconda3/envs/Astropy_Playground/lib/python3.10/site-packages/astropy/cosmology/parameter.py:176, in Parameter.validate(self, cosmology, value)
    161 def validate(self, cosmology, value):
    162     """Run the validator on this Parameter.
    163 
    164     Parameters
   (...)
    174         (yes, that parameter order).
    175     """
--> 176     return self.fvalidate(cosmology, self, value)

File ~/opt/anaconda3/envs/Astropy_Playground/lib/python3.10/site-packages/astropy/cosmology/flrw/base.py:251, in FLRW.m_nu(self, param, value)
    248     return None  # None, regardless of input
    250 # Validate / set units
--> 251 value = _validate_with_unit(self, param, value)
    253 # Check values and data shapes
    254 if value.shape not in ((), (nneutrinos,)):

File ~/opt/anaconda3/envs/Astropy_Playground/lib/python3.10/site-packages/astropy/cosmology/parameter.py:334, in _validate_with_unit(cosmology, param, value)
    332 if param.unit is not None:
    333     with u.add_enabled_equivalencies(param.equivalencies):
--> 334         value = u.Quantity(value, param.unit)
    335 return value

File ~/opt/anaconda3/envs/Astropy_Playground/lib/python3.10/site-packages/astropy/units/quantity.py:457, in Quantity.__new__(cls, value, unit, dtype, copy, order, subok, ndmin)
    455 unit_string = v.string[v.end():].strip()
    456 if unit_string:
--> 457     value_unit = Unit(unit_string)
    458     if unit is None:
    459         unit = value_unit  # signal no conversion needed below.

File ~/opt/anaconda3/envs/Astropy_Playground/lib/python3.10/site-packages/astropy/units/core.py:2040, in _UnitMetaClass.__call__(self, s, represents, format, namespace, doc, parse_strict)
   2031 msg = ("'{}' did not parse as {}unit: {} "
   2032        "If this is meant to be a custom unit, "
   2033        "define it with 'u.def_unit'. To have it "
   (...)
   2037        "https://docs.astropy.org/en/latest/units/combining_and_defining.html"
   2038        .format(s, format_clause, str(e)))
   2039 if parse_strict == 'raise':
-> 2040     raise ValueError(msg)
   2041 elif parse_strict == 'warn':
   2042     warnings.warn(msg, UnitsWarning)

ValueError: '.. 0.06' did not parse as unit: Syntax error parsing unit '.. 0.06' If this is meant to be a custom unit, define it with 'u.def_unit'. To have it recognized inside a file reader or other code, enable it with 'u.add_enabled_units'. For details, see https://docs.astropy.org/en/latest/units/combining_and_defining.html

I figured out the issue. It turns out Astropy's LaTeX reader doesn't work correctly...
The units don't round-trip, causing the whole column to be read as a string.
We'll have to get that fixed first!

@nstarman

@nstarman Could you please guide me on how to fix this problem? Will I have to make changes in the read() method here

astropy/astropy/io/ascii/core.py

Line 1101 in 9910521

def read(self, table):

or in latex class over here

astropy/astropy/io/ascii/latex.py

Line 179 in 9910521

class Latex(core.BaseReader):

@taldcroft

Oh, don't tackle that in the PR! way beyond scope 😆. I've opened #14853 to try to address this issue. I've asked @taldcroft for his opinion on how to fix this.

Sounds good I will wait for the issue to get fixed.

@Mubin17

@Mubin17 If you're interested in contributing a read & write method, the AAS MRT (https://docs.astropy.org/en/stable/io/unified.html#built-in-table-readers-writers) one would be a good one. That already has unit support when reading, so its should be very similar to the LaTeX PR you just did.

I have a code that can turn a latex file into a txt (almost done) and I can add a word extra feature to be able to handle images and text formatting is that what you want or the desired output?

I think this Issue is more focused on getting the Cosmology writer/reader to work with Astropy Table I/O to write / read in a latex table. It was decided in #14853 that reading in units is too challenging, but the broader issue of writing to a latex and reading from that latex are still available, if you are interesting in contributing!

I’d like to take this “good first issue” and add a LaTeX reader/writer for astropy.cosmology. My plan is to create read_latex and write_latex functions in a new latex.py module (with accompanying tests) and expose them in init.py. I’ve already sketched out the code locally and will open a draft PR soon. Let me know if that sounds good, or if there’s any additional guidance before I begin! Thanks.

Add LaTex reader/writer for astropy.cosmology (issue astropy#14837)

@nstarman

@nstarman Hi, Nathaniel I recently tried to contribute to this issue. Can you please take a look at code and tell me if some improvement needs to be done...?

Hello, I would like to contribute to this issue. Would it be possible to assign it to me?

@Pittu-Sharma

@Pittu-Sharma thanks for your interest in this issue. Someone is already working on this issue. If youre still interested I can suggest other Issues!

Hello, I would like to contribute to this issue. Would it be possible to assign it to me? OR can you please suggest me other issues to work upon?

hey ,can i work on this issue

Is this issue still relevant? I would like to work on it if it is still open.

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Register LaTeX reader for Cosmology #14837

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Register LaTeX reader for Cosmology #14837

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nstarman commented on May 17, 2023

pllim commented on May 17, 2023

nstarman commented on May 17, 2023

Mubin17 commented on May 17, 2023

nstarman commented on May 18, 2023

Mubin17 commented on May 18, 2023

nstarman commented on May 19, 2023

Mubin17 commented on May 22, 2023

nstarman commented on May 23, 2023

Mubin17 commented on May 25, 2023

nstarman commented on May 25, 2023

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abdelrahman-hosam commented on Mar 21, 2025

nstarman commented on Mar 25, 2025

anishgkr21 commented on Jun 8, 2025

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Pittu-Sharma commented on Feb 13, 2026

nstarman commented on Mar 1, 2026

molly22-byte commented on Mar 16, 2026

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