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+# Copyright (c) 2016 Weitian LI <liweitianux@live.com>
+# MIT license
+
+
+"""
+Retrieve the Galactic SNRs catalog data by parsing the web by /D. A. Green/:
+
+ http://www.mrao.cam.ac.uk/surveys/snrs/
+ http://www.mrao.cam.ac.uk/surveys/snrs/snrs.data.html
+"""
+
+
+import os
+import re
+import logging
+from collections import OrderedDict
+
+import requests
+import bs4
+
+
+logger = logging.getLogger(__name__)
+
+
+class SNRDataGreen:
+ """Class for Green's Galactic SNRs catalog data parse and manipulation.
+
+ The available SNR data:
+ - glon, glat : Galactic longitude, latitude (rounded to 0.1deg) [degree]
+ - ra, dec : Right ascension, Declination (J2000) [degree]
+ - size : angular size [degree]: (diameter, diameter) or (major, minor)
+ - type : shape type: (shape, flag) with shapes of "S" (shell),
+ "F" (filled-center), "C" (composite), and flag "?" if uncertain.
+ - flux : flux density at 1 GHz [Jy]
+ - specindex : Spectral index of the integrated radio emission
+ - other_names : other name(s) commonly used for the SNR
+
+ For more detailed description about the SNR catalog, refer to:
+ http://www.mrao.cam.ac.uk/surveys/snrs/snrs.info.html
+ """
+ def __init__(self, dstr):
+ self.data = self.parse(dstr)
+
+ @classmethod
+ def parse(cls, dstr):
+ """Parse the SNR data string, for one SNR object.
+
+ Parameters
+ ----------
+ dstr : str
+ String containing the SNR data
+
+ Returns
+ -------
+ data : dict
+ A data dictionary containing the parsed SNR data
+ """
+ pattern = re.compile((
+ r"^\s*(?P<glon>\d+\.\d+)\s+(?P<glat>[-+]?\d+\.\d+)\s+"
+ r"(?P<ra>\d{2}\s+\d{2}\s+\d{2})\s+(?P<dec>[-+]?\d{2}\s+\d{2})\s+"
+ r"(?P<size>[0-9.]+\??|[0-9.]+x[0-9.]+\??|\?)\s+"
+ r"(?P<shape>[SCF?]{1,2})\s+"
+ r"(?P<flux>\>?\d+\.\d+\??|\>?\d+\??|\?)\s+"
+ r"(?P<specindex>\d+\.\d+\??|\d+\??|\?|varies)\s*"
+ r"(?P<othernames>.*)$"))
+ match = pattern.match(dstr)
+ data = OrderedDict([
+ ("glon", float(match.group("glon"))),
+ ("glat", float(match.group("glat"))),
+ ("ra", cls._parse_ra(match.group("ra"))),
+ ("dec", cls._parse_dec(match.group("dec"))),
+ ("size", cls._parse_size(match.group("size"))),
+ ("shape", cls._parse_shape(match.group("shape"))),
+ ("flux", cls._parse_flux(match.group("flux"))),
+ ("specindex", cls._parse_specindex(match.group("specindex"))),
+ ("othernames", cls._parse_othernames(match.group("othernames"))),
+ ])
+ return data
+
+ @staticmethod
+ def _parse_ra(s):
+ """Parse the R.A. string "hh mm ss" to degree [0, 360)"""
+ pattern = re.compile(r"(?P<hh>\d+)\s+(?P<mm>\d+)\s+(?P<ss>\d+)")
+ match = pattern.match(s)
+ hh = float(match.group("hh"))
+ mm = float(match.group("mm"))
+ ss = float(match.group("ss"))
+ return (hh*15.0 + mm*15.0/60.0 + ss*15.0/3600.0)
+
+ @staticmethod
+ def _parse_dec(s):
+ """Parse the Dec. string "dd mm" to degree [-90, 90]"""
+ pattern = re.compile(r"(?P<sign>[-+]?)(?P<dd>\d+)\s+(?P<mm>\d+)")
+ match = pattern.match(s)
+ if match.group("sign") == "-":
+ sign = -1.0
+ else:
+ sign = 1.0
+ dd = float(match.group("dd"))
+ mm = float(match.group("mm"))
+ return sign * (dd + mm/60.0)
+
+ @staticmethod
+ def _parse_size(s):
+ """Parse the SNR angular size string.
+
+ Returns
+ -------
+ major : float
+ minor : float
+ flag : str
+ (diameter, diameter) of the SNR if approximately circular;
+ (major axis, minor axis) if SNR is elongated.
+ All values are in unit [ degree ].
+ Possible flag: "", "?" (uncertain)
+ """
+ if s.endswith("?"):
+ flag = "?"
+ s = s.rstrip("?")
+ else:
+ flag = ""
+ try:
+ major, minor = map(float, s.split("x"))
+ except ValueError:
+ major = minor = float(s)
+ return (major, minor, flag)
+
+ @staticmethod
+ def _parse_shape(s):
+ """Parse the SNR shape (a.k.a. type) string.
+
+ Returns
+ -------
+ shape : str
+ flag : str
+ Possible shapes are "S" (shell), "F" (filled-center),
+ "C" (composite), or None (very uncertain);
+ Possible flag: "", "?" (uncertain)
+ """
+ flag = ""
+ if s.endswith("?"):
+ flag += "?"
+ s = s.rstrip("?")
+ if s != "":
+ shape = s
+ else:
+ shape = None
+ return (shape, flag)
+
+ @staticmethod
+ def _parse_flux(s):
+ """Parse the flux density string.
+
+ Returns
+ -------
+ flux : float
+ flag : str
+ Flux density [ Jy ] at 1GHz, None if the value is uncertain.
+ Possible flag: "", "?", ">", ">?"
+ """
+ flag = ""
+ if s.startswith(">"):
+ flag += ">"
+ s = s.lstrip(">")
+ if s.endswith("?"):
+ flag += "?"
+ s = s.rstrip("?")
+ try:
+ flux = float(s)
+ except ValueError:
+ flux = None
+ return (flux, flag)
+
+ @staticmethod
+ def _parse_specindex(s):
+ """Parse the spectral index string.
+
+ Returns
+ -------
+ specindex : float
+ flag : str
+ Spectral index, None if the value is uncertain.
+ Possible flag: "", "?", "varies"
+ """
+ if s == "varies":
+ specindex = None
+ flag = "varies"
+ elif s.endswith("?"):
+ flag = "?"
+ s = s.rstrip("?")
+ try:
+ specindex = float(s)
+ except ValueError:
+ specindex = None
+ else:
+ specindex = float(s)
+ flag = ""
+ return (specindex, flag)
+
+ @staticmethod
+ def _parse_othernames(s):
+ """Parse the other names string to a list of names."""
+ s = s.strip()
+ if s:
+ return s.split(",")
+ else:
+ return []
+
+ @property
+ def name(self):
+ pattern = "G{glon:05.1f}{glat:+05.1f}"
+ return pattern.format(**self.data)
+
+ @property
+ def othernames(self):
+ return self.data["othernames"]
+
+ @property
+ def glon(self):
+ return self.data["glon"]
+
+ @property
+ def glat(self):
+ return self.data["glat"]
+
+ @property
+ def ra(self):
+ return self.data["ra"]
+
+ @property
+ def dec(self):
+ return self.data["dec"]
+
+ @property
+ def size(self):
+ return self.data["size"]
+
+ @property
+ def shape(self):
+ return self.data["shape"]
+
+ @property
+ def flux(self):
+ return self.data["flux"]
+
+ @property
+ def specindex(self):
+ return self.data["specindex"]
+
+ @property
+ def data_flat(self):
+ """Get the data with tuple items flattened for easier CSV process"""
+ data = OrderedDict([
+ ("name", self.name),
+ ("glon", self.glon),
+ ("glat", self.glat),
+ ("ra", self.ra),
+ ("dec", self.dec),
+ ("size_major", self.size[0]),
+ ("size_minor", self.size[1]),
+ ("size_flag", self.size[2]),
+ ("shape", self.shape[0]),
+ ("shape_flag", self.shape[1]),
+ ("flux", self.flux[0]),
+ ("flux_flag", self.flux[1]),
+ ("specindex", self.specindex[0]),
+ ("specindex_flag", self.specindex[1]),
+ ("othernames", self.othernames),
+ ])
+ return data
+
+
+def retrieve_snr_data_green(url):
+ """Retrieve D. A. Green's Galactic SNRs catalog and parse the HTML
+ contents to extract the catalog data.
+
+ Parameters
+ ----------
+ url : str
+ URL to the D. A. Green's SNRs catalog summary data page,
+ can also be the path to the local HTML file.
+
+ Returns
+ -------
+ snrdata : list[str]
+ A string list with each line representing the information of
+ one SNR object.
+
+ Data string format:
+ - Column 1, 2: Galactic longitude (l) and latitude (b)
+ - Column 3-5: R.A. J2000 (hh mm ss)
+ - Column 6, 7: Dec. J2000 (dd mm)
+ - Column 8: Size [ arcmin ], `r` if circular, `Mxm` if elliptical;
+ may also contains a "?"
+ - Column 9: Type (e.g., S, C, S?, C?)
+ - Column 10: Flux density at 1 GHz [ Jy ]
+ - Column 11: Spectral index (may contains "?" or be "varies")
+ - Column 12: Other name(s), separated by ","
+ """
+ # Strip the beginning "file://" if presents
+ url = re.sub(r"^file://", "", url)
+ logger.info("Retrieve Galactic SNRs catalog from: {0}".format(url))
+ if os.path.exists(url):
+ # A local HTML file
+ html = open(url).read()
+ else:
+ # Remote web page
+ r = requests.get(url)
+ r.raise_for_status()
+ html = r.text
+ logger.info("Parse the HTML contents ...")
+ soup = bs4.BeautifulSoup(html, "html.parser")
+ snrdata_tag = soup.body.pre
+ snrdata_str = [ch.strip() if isinstance(ch, bs4.element.NavigableString)
+ else ch.string.strip()
+ for ch in snrdata_tag.children]
+ # Remove the header row
+ del snrdata_str[0]
+ # Strip the last data row
+ snrdata_str[-1] = re.sub(r"[-\s]*$", "", snrdata_str[-1])
+ # The remaining SNR data string list should be even-length, since
+ # every two items are the Galactic coordinate and other information.
+ if len(snrdata_str) % 2 != 0:
+ raise ValueError("length of the parsed SNR data str list is ODD")
+ # Concatenate every two items corresponding to the same SNR object
+ snrdata_str2 = [" ".join(x) for x in zip(snrdata_str[0::2],
+ snrdata_str[1::2])]
+ logger.info("Done parse the HTML contents: "
+ "got {0} SNR objects".format(len(snrdata_str2)))
+ return snrdata_str2
Copyright © 2017-2018 Aaron LI. All Rights Reserved.