Source code for astroML.datasets.rrlyrae_mags
import os
import numpy as np
from . import get_data_home
from . import fetch_sdss_S82standards
from .tools import download_with_progress_bar
DATA_URL = ("https://github.com/astroML/astroML-data/raw/master/datasets/"
"RRLyrae.fit")
[docs]def fetch_rrlyrae_mags(data_home=None, download_if_missing=True):
"""Loader for RR-Lyrae data
Parameters
----------
data_home : optional, default=None
Specify another download and cache folder for the datasets. By default
all astroML data is stored in '~/astroML_data'.
download_if_missing : optional, default=True
If False, raise a IOError if the data is not locally available
instead of trying to download the data from the source site.
Returns
-------
data : recarray, shape = (483,)
record array containing imaging data
Examples
--------
>>> from astroML.datasets import fetch_rrlyrae_mags
>>> data = fetch_rrlyrae_mags() # doctest: +IGNORE_OUTPUT +REMOTE_DATA
>>> # number of objects in dataset
>>> data.shape # doctest: +REMOTE_DATA
(483,)
Notes
-----
This data is from table 1 of Sesar et al 2010 ApJ 708:717
"""
# fits is an optional dependency: don't import globally
from astropy.io import fits
data_home = get_data_home(data_home)
archive_file = os.path.join(data_home, os.path.basename(DATA_URL))
if not os.path.exists(archive_file):
if not download_if_missing:
raise IOError('data not present on disk. '
'set download_if_missing=True to download')
fitsdata = download_with_progress_bar(DATA_URL)
open(archive_file, 'wb').write(fitsdata)
hdulist = fits.open(archive_file)
return np.asarray(hdulist[1].data)
[docs]def fetch_rrlyrae_combined(data_home=None, download_if_missing=True):
"""Loader for RR-Lyrae combined data
This returns the combined RR-Lyrae colors and SDSS standards colors.
The RR-Lyrae sample is confirmed through time-domain observations;
this result in a nice dataset for testing classification routines.
Parameters
----------
data_home : optional, default=None
Specify another download and cache folder for the datasets. By default
all astroML data is stored in '~/astroML_data'.
download_if_missing : optional, default=True
If False, raise a IOError if the data is not locally available
instead of trying to download the data from the source site.
Returns
-------
X : ndarray
a shape (n_samples, 4) array. Columns are u-g, g-r, r-i, i-z
y : ndarray
a shape (n_samples,) array of labels. 1 indicates an RR Lyrae,
0 indicates a background star.
"""
# ----------------------------------------------------------------------
# Load data
kwds = dict(data_home=data_home,
download_if_missing=download_if_missing)
rrlyrae = fetch_rrlyrae_mags(**kwds)
standards = fetch_sdss_S82standards(**kwds)
# ------------------------------------------------------------
# perform color cuts on standard stars
# these come from eqns 1-4 of Sesar et al 2010, ApJ 708:717
u_g = standards['mmu_u'] - standards['mmu_g']
g_r = standards['mmu_g'] - standards['mmu_r']
r_i = standards['mmu_r'] - standards['mmu_i']
i_z = standards['mmu_i'] - standards['mmu_z']
standards = standards[(u_g > 0.7) & (u_g < 1.35) &
(g_r > -0.15) & (g_r < 0.4) &
(r_i > -0.15) & (r_i < 0.22) &
(i_z > -0.21) & (i_z < 0.25)]
# ----------------------------------------------------------------------
# get magnitudes and colors; split into train and test sets
mags_rr = np.vstack([rrlyrae[f + 'mag'] for f in 'ugriz'])
colors_rr = mags_rr[:-1] - mags_rr[1:]
mags_st = np.vstack([standards['mmu_' + f] for f in 'ugriz'])
colors_st = mags_st[:-1] - mags_st[1:]
# stack the two sets of colors together
X = np.vstack((colors_st.T, colors_rr.T))
y = np.zeros(X.shape[0])
y[-colors_rr.shape[1]:] = 1
return X, y
