tessl/pypi-astropy
Astronomy and astrophysics core library providing comprehensive tools for astronomical computations and data handling
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fits-io.mddocs/
FITS File I/O
Complete FITS (Flexible Image Transport System) file support for reading, writing, and manipulating astronomical data files with headers, image data, and binary tables.
Capabilities
Basic FITS Operations
High-level functions for common FITS file operations including reading data and headers, writing files, and updating existing files.
def open(name, mode='readonly', memmap=None, save_backup=False, cache=True, lazy_load_hdus=True, **kwargs):
"""
Open a FITS file and return an HDUList object.
Parameters:
- name: file name or file-like object
- mode: file access mode ('readonly', 'update', 'append', 'denywrite', 'ostream')
- memmap: use memory mapping for large files
- save_backup: save backup when updating files
- cache: cache file in memory
- lazy_load_hdus: load HDUs only when accessed
Returns:
HDUList: list of Header Data Units
"""
def getdata(filename, *args, header=False, lower=None, upper=None, view=None, **kwargs):
"""
Get data from FITS file.
Parameters:
- filename: FITS file name
- *args: HDU specification (ext, extname, extver)
- header: also return header
- lower, upper: data range bounds
- view: numpy slice for data subset
Returns:
ndarray or tuple: data array, optionally with header
"""
def getheader(filename, *args, **kwargs):
"""
Get header from FITS file.
Parameters:
- filename: FITS file name
- *args: HDU specification
Returns:
Header: FITS header object
"""
def writeto(filename, data, header=None, output_verify='exception', overwrite=False, checksum=False, **kwargs):
"""
Write data to FITS file.
Parameters:
- filename: output file name
- data: data array to write
- header: FITS header
- output_verify: verification level
- overwrite: overwrite existing file
- checksum: compute checksums
"""
def append(filename, data, header=None, checksum=False, verify=True, **kwargs):
"""Append HDU to existing FITS file."""
def update(filename, data, *args, header=None, verify=True, **kwargs):
"""Update HDU in existing FITS file."""
def info(filename, output=None, **kwargs):
"""
Print summary information about FITS file.
Parameters:
- filename: FITS file name
- output: output stream (default: stdout)
"""HDU Classes and Structure
HDU (Header Data Unit) classes representing different types of FITS extensions with headers and data.
class HDUList:
"""
List-like container for FITS Header Data Units.
Parameters:
- hdus: list of HDU objects
- file: associated file object
"""
def __init__(self, hdus=[], file=None): ...
def writeto(self, fileobj, output_verify='exception', overwrite=False, checksum=False):
"""Write HDUList to file."""
def append(self, hdu):
"""Append HDU to list."""
def insert(self, index, hdu):
"""Insert HDU at specified index."""
def info(self, output=None):
"""Print information about HDUs."""
def verify(self, option='warn'):
"""Verify FITS standard compliance."""
def close(self):
"""Close associated file."""
def __getitem__(self, key):
"""Get HDU by index, name, or (name, version)."""
class PrimaryHDU:
"""
Primary Header Data Unit (first HDU in FITS file).
Parameters:
- data: data array
- header: FITS header
- do_not_scale_image_data: disable automatic scaling
- uint: treat signed integers as unsigned
- scale_back: scale data when writing
"""
def __init__(self, data=None, header=None, do_not_scale_image_data=False, uint=False, scale_back=None): ...
@property
def data(self):
"""HDU data array."""
@property
def header(self):
"""HDU header."""
def writeto(self, name, output_verify='exception', overwrite=False, checksum=False): ...
class ImageHDU(PrimaryHDU):
"""Image extension HDU."""
def __init__(self, data=None, header=None, name=None, **kwargs): ...
class BinTableHDU:
"""
Binary table HDU.
Parameters:
- data: table data (structured array, Table, etc.)
- header: FITS header
- name: extension name
- uint: handle unsigned integers
- character_as_bytes: handle character columns
"""
def __init__(self, data=None, header=None, name=None, uint=False, character_as_bytes=False): ...
@classmethod
def from_columns(cls, columns, header=None, nrows=None, fill=False, **kwargs):
"""Create from Column objects."""
class TableHDU:
"""ASCII table HDU."""
def __init__(self, data=None, header=None, name=None): ...
class CompImageHDU:
"""Compressed image HDU."""
def __init__(self, data=None, header=None, name=None, compression_type='RICE_1', **kwargs): ...Header Manipulation
FITS header handling with keyword management, comments, and history records.
class Header:
"""
FITS header with ordered keyword-value pairs.
Parameters:
- cards: list of Card objects or keyword-value pairs
- txtfile: read from text file
- copy: copy input data
"""
def __init__(self, cards=[], txtfile=None, copy=True): ...
def __getitem__(self, key):
"""Get header value by keyword."""
def __setitem__(self, key, value):
"""Set header keyword value."""
def __delitem__(self, key):
"""Delete header keyword."""
def __contains__(self, key):
"""Check if keyword exists."""
def append(self, card=None, useblanks=True, bottom=False, end=False):
"""Append card to header."""
def insert(self, key, card, useblanks=True, after=False):
"""Insert card before/after specified keyword."""
def remove(self, keyword, ignore_missing=False, remove_all=False):
"""Remove keyword from header."""
def rename_keyword(self, oldkeyword, newkeyword, force=False):
"""Rename header keyword."""
def set(self, keyword, value=None, comment=None, before=None, after=None, savecomment=False):
"""Set keyword value with optional positioning."""
def update(self, *args, **kwargs):
"""Update header with new keywords."""
def add_history(self, value, before=None, after=None):
"""Add HISTORY record."""
def add_comment(self, value, before=None, after=None):
"""Add COMMENT record."""
def add_blank(self, value='', before=None, after=None):
"""Add blank card."""
def copy(self, strip=False):
"""Copy header."""
class Card:
"""
Individual FITS header card (keyword-value-comment).
Parameters:
- keyword: FITS keyword (8 characters max)
- value: keyword value
- comment: keyword comment
- image: create from raw 80-character string
"""
def __init__(self, keyword=None, value=None, comment=None, image=None): ...
@property
def keyword(self):
"""FITS keyword."""
@property
def value(self):
"""Keyword value."""
@property
def comment(self):
"""Keyword comment."""
@property
def image(self):
"""80-character card image."""Usage Examples
Basic FITS File Operations
from astropy.io import fits
import numpy as np
# Read FITS file
with fits.open('image.fits') as hdul:
fits.info('image.fits') # Print file info
header = hdul[0].header # Primary header
data = hdul[0].data # Primary data
# Access extension by name
if 'EVENTS' in hdul:
events = hdul['EVENTS'].data
# Quick data access
data = fits.getdata('image.fits')
header = fits.getheader('image.fits')
data, header = fits.getdata('image.fits', header=True)Creating and Writing FITS Files
# Create simple image
data = np.random.random((100, 100))
# Write with basic header
fits.writeto('output.fits', data, overwrite=True)
# Create custom header
hdr = fits.Header()
hdr['OBJECT'] = 'M31'
hdr['EXPTIME'] = 600.0
hdr['FILTER'] = 'V'
hdr.add_comment('This is a test image')
fits.writeto('output_with_header.fits', data, header=hdr, overwrite=True)