Python3 support

[telegraphic]

J. Wright got filterbank.py working in Python 3, but it required some changes due to how Py3 handles strings. Here's the diff:

151c151
<     f = open(filename, 'r')

---
>     f = open(filename, 'rb')
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<     header_str = ''

---
>     header_str = b""
159,160c159,160
<         if 'HEADER_START' in header_sub:
<             idx_start = header_sub.index('HEADER_START') + len('HEADER_START')

---
>         if b"HEADER_START" in header_sub:
>             idx_start = header_sub.index(b"HEADER_START") + len(b"HEADER_START")
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<         if 'HEADER_END' in header_sub:

---
>         if b"HEADER_END" in header_sub:
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<             idx_end = header_sub.index('HEADER_END')

---
>             idx_end = header_sub.index(b"HEADER_END")
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<     f = open(filename, 'r')

---
>     f = open(filename, 'rb')
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<         if 'HEADER_END' in header_sub:
<             idx_end = header_sub.index('HEADER_END') + len('HEADER_END')

---
>         if b"HEADER_END" in header_sub:
>             idx_end = header_sub.index(b"HEADER_END") + len(b"HEADER_END")
212c212,213
<     for keyword in header_keyword_types.keys():

---
>     for keyword_str in list(header_keyword_types.keys()):
>         keyword = keyword_str.encode("utf-8")
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<             dtype = header_keyword_types.get(keyword, 'str')

---
>             dtype = header_keyword_types.get(keyword_str, 'str')
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<             dtype = header_keyword_types[keyword]

---
>             dtype = header_keyword_types[keyword_str]
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<                 header_dict[keyword] = val

---
>                 header_dict[keyword_str] = val
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<                 header_dict[keyword] = val

---
>                 header_dict[keyword_str] = val
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<                 header_dict[keyword] = str_val

---
>                 header_dict[keyword_str] = str_val.decode("utf-8")
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<                 
<                 if keyword == 'src_raj':

---
>                 if keyword_str == 'src_raj':
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<                 header_dict[keyword] = val                

---
>                 header_dict[keyword_str] = val                
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<             print dd.shape
<             print n_ints, n_ifs, n_chans

---
>             print(dd.shape)
>             print(n_ints, n_ifs, n_chans)
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<         for key, val in self.header.items():

---
>         for key, val in list(self.header.items()):
339c339
<             print "%16s : %32s" % (key, val)

---
>             print("%16s : %32s" % (key, val))
431c431
<         print plot_data.shape, plot_f.shape

---
>         print(plot_data.shape, plot_f.shape)
487c487
<             print "Start freq: %2.2f" % args.f_start

---
>             print("Start freq: %2.2f" % args.f_start)
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<             print "Stop freq: %2.2f" % args.f_stop

---
>             print("Stop freq: %2.2f" % args.f_stop)
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<         print "Error: Start and stop frequencies must lie inside file's frequency range."
<         print "i.e. between %2.2f-%2.2f MHz." % (fil.freqs[0], fil.freqs[-1])

---
>         print("Error: Start and stop frequencies must lie inside file's frequency range.")
>         print("i.e. between %2.2f-%2.2f MHz." % (fil.freqs[0], fil.freqs[-1]))

Probably requires some Py2/Py3 conditionals in the code

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Note to self: We have almost certainly broken py3 support.

[telegraphic]

I think we fixed Py3 support so closing issue. Can open again if we break it again.