Create Simulated Catalog

This module provides functionality to create a simulated catalog using data from the Roman Space Telescope. It leverages the LePhare photometric redshift estimation tool and other utilities to generate simulated data, process it, and save it in a structured format.

Module API

class roman_photoz.create_simulated_catalog.SimulatedCatalog(nobj: int = 1000, mag_noise: float = 0.1)

Bases: object

A class to create a simulated catalog using the Roman telescope data.

data

A dictionary to store the data.

Type:: OrderedDict

lephare_config

Configuration for LePhare.

Type:: dict

flux_cols

List of flux columns.

Type:: list

flux_err_cols

List of flux error columns.

Type:: list

inform_stage

Placeholder for inform stage.

Type:: None

estimated

Holds all the results from roman_photoz.

Type:: None

filter_lib

Placeholder for filter library.

Type:: None

simulated_data_filename

Filename for the simulated data.

Type:: str

simulated_data

Placeholder for simulated data.

Type:: None

abmag_to_njy(abmag)

add_error(catalog, mag_noise: float = 0.1, seed: int = 42)

Add a Gaussian error to each magnitude column in the catalog.

For each magnitude column, this method adds: + a Gaussian noise with a mean equal to the original value and a standard deviation of mag_noise + an error column (<magnitude_column>_err) with values set to mag_noise.

Parameters:

catalog (np.ndarray) – The catalog data.
mag_noise (float, optional) – The standard deviation of the Gaussian noise to be added to the observed magnitudes (default: 0.1).
seed (int, optional) – The seed for the random number generator.

Returns:

The catalog data with error columns added.

Return type:

np.ndarray

add_ids(catalog)

Add an ID column to the catalog.

Parameters:: catalog (np.ndarray) – The catalog data.
Returns:: The catalog data with an ID column added.
Return type:: np.ndarray

create_column_names()

create_filter_files()

Create filter files for the Roman telescope.

This method checks if the required filter files are present in the specified directory. If not, it generates them using the create_roman_filters module.

Raises:: FileNotFoundError – If the filter files cannot be created or found.

create_header(catalog_name: str)

Create the header for the catalog.

Parameters:: catalog_name (str) – The name of the catalog file.
Returns:: The list of column names for the catalog.
Return type:: list

create_simulated_data()

Generate simulated data using the LePhare configuration.

This method prepares the LePhare environment and generates simulated data for galaxies, stars, and quasars based on the provided configuration.

Raises:: RuntimeError – If the LePhare preparation fails or the configuration is invalid.

create_simulated_input_catalog(output_filename: str = 'roman_simulated_catalog.parquet', output_path: str = '')

Create a simulated input catalog from the simulated data.

read the ROMAN_SIMULATED_MAGS.dat produced by LePhare’s
prepare method in create_simulated_input_catalog. The columns name are defined by LePhare.
format the columns name to match Roman catalog’s specifications

create_simulated_roman_catalog(catalog)

Update the Roman catalog template with the simulated data.

Parameters:: catalog (np.ndarray) – The catalog data to update the Roman catalog template with.

is_folder_not_empty(folder_path: str, partial_text: str) → bool

Check if a folder exists and contains files with the specified partial text.

Parameters:

folder_path (str) – The path to the folder.
partial_text (str) – The partial text to look for in filenames.

Returns:

True if the folder exists and contains files with the partial text, False otherwise.

Return type:

bool

pick_random_lines(num_lines: int)

Pick random lines from the data array.

Parameters:: num_lines (int) – The number of random lines to pick.
Returns:: An array containing the randomly picked lines.
Return type:: np.ndarray

process(output_path: str = '', output_filename: str = 'roman_simulated_catalog.parquet'): Run the process to create the simulated catalog.

read_roman_template_catalog()

roman_photoz.create_simulated_catalog.main()

Command-Line Usage

The module can also be executed as a standalone script to create a simulated catalog. It provides command-line arguments for specifying the output path and filename.

Arguments

--output_path (str) Path to save the output catalog (default: LEPHAREWORK).
--output_filename (str) Filename for the output catalog (default: roman_simulated_catalog.asdf).

Example

python -m roman_photoz.create_simulated_catalog --output_path=/path/to/output/ --output_filename=simulated_catalog.asdf

Usage Examples

The following example demonstrates how to programmatically create a simulated catalog:

from roman_photoz.create_simulated_catalog import CreateSimulatedCatalog

# Initialize the catalog creator with default parameters
creator = CreateSimulatedCatalog()

# Create a simulated catalog with 100 sources
catalog = creator.create_catalog(n_sources=100)

# Save the catalog to a file
creator.save_catalog(
    catalog,
    output_path="/path/to/output/",
    output_filename="simulated_catalog.asdf"
)

print(f"Simulated catalog with {len(catalog)} sources created successfully")