65 lines
2.2 KiB
Python
65 lines
2.2 KiB
Python
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#!/usr/bin/env python3
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import os
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import re
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from datetime import datetime
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import numpy as np
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class Spectrogram:
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"""Spectrogram class"""
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def __init__(self, path, prefix, ifile, nsub, siteid):
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"""Define a spectrogram"""
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# Read first file to get number of channels
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fname = os.path.join(path, "{:s}_{:06d}.bin".format(prefix, ifile))
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with open(fname, "rb") as fp:
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header = parse_header(fp.read(256))
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# Set frequencies
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freq = np.linspace(-0.5*header["bw"], 0.5*header["bw"], header["nchan"], endpoint=False)+header["freq"]+0.5*header["bw"]/header["nchan"]
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# Loop over subints and files
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zs = []
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mjds = []
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isub = 0;
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while isub<nsub:
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# File name of file
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fname = os.path.join(path, "{:s}_{:06d}.bin".format(prefix, ifile))
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with open(fname, "rb") as fp:
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next_header = fp.read(256)
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while next_header:
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header = parse_header(next_header)
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# mjds.append(Time(header["utc_start"], format="datetime", scale="utc").mjd+0.5*header["length"]/86400.0)
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zs.append(np.fromfile(fp, dtype=np.float32, count=header["nchan"]))
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next_header = fp.read(256)
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isub += 1
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ifile += 1
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self.z = np.transpose(np.vstack(zs))
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self.mjd = np.array(mjds)
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self.freq = freq
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self.siteid = siteid
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self.nchan = self.z.shape[0]
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self.nsub = self.z.shape[1]
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def parse_header(header_b):
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header_s = header_b.decode('ASCII').strip('\x00')
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regex = r"^HEADER\nUTC_START (.*)\nFREQ (.*) Hz\nBW (.*) Hz\nLENGTH (.*) s\nNCHAN (.*)\nNSUB (.*)\nEND\n$"
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try:
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match = re.fullmatch(regex, header_s, re.MULTILINE)
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except AttributeError:
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match = re.match(regex, header_s, flags=re.MULTILINE)
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utc_start = datetime.strptime(match.group(1), '%Y-%m-%dT%H:%M:%S.%f')
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return {'utc_start': utc_start,
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'freq': float(match.group(2)),
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'bw': float(match.group(3)),
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'length': float(match.group(4)),
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'nchan': int(match.group(5)),
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'nsub': int(match.group(6))}
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