source: trunk/python/scantable.py@ 110

Last change on this file since 110 was 102, checked in by mar637, 20 years ago

The main pyhton asap container class

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  • Property svn:keywords set to Author Date Id Revision
File size: 7.7 KB
Line 
1from asap._asap import sdtable
2from numarray import ones
3import sys
4
5class scantable(sdtable):
6 """
7 The ASAP container for scans
8 """
9 def functions(self):
10 return ['copy','get_scan','summary','rms','set_unit','create_mask']
11
12 def __init__(self, filename):
13 """
14 Create a scantable from a saved one or make a reference
15 Parameters:
16 filename: the name of an asap table on disk, or
17 [advanced] a refernce to an existing
18 scantable
19 """
20 sdtable.__init__(self, filename)
21 self._unit = 'channel'
22
23 def copy(self):
24 """
25 Return a copy of this scantable.
26 Parameters:
27
28 Example:
29 copiedscan = scan.copy()
30 """
31 sd = sdtable._copy(self)
32 return scantable(sd)
33 def get_scan(self, scanid=None):
34 """
35 Return a specific scan (by scanno) or collection of scans (by
36 source name) in a new scantable.
37 Parameters:
38 scanid: a scanno or a source name
39 Example:
40 scan.getscan('323p459')
41 # gets all scans containing the source '323p459'
42 """
43 if scanid is None:
44 print "Please specify a scan no or name to retrieve from the scantable"
45 try:
46 if type(scanid) is str:
47 s = sdtable.getsource(self,scanid)
48 return scantable(s)
49 elif type(scanid) is int:
50 s = sdtable.getscan(self,scanid)
51 return scantable(s)
52 except RuntimeError:
53 print "Couldn't find any match."
54
55 def __str__(self):
56 return sdtable.summary(self)
57
58 def summary(self,filename=None):
59 """
60 Print a summary of the contents of this scantable.
61 Parameters:
62 filename: the name of a file to write the putput to
63 Default - no file output
64 """
65 info = sdtable.summary(self)
66 if filename is not None:
67 data = open(filename, 'w')
68 data.write(info)
69 data.close()
70 print info
71
72 def set_selection(self, thebeam=0,theif=0,thepol=0):
73 """
74 Set the spectrum for individual operations.
75 Parameters:
76 thebeam,theif,thepol: a number
77 Example:
78 scan.set_selection(0,0,1)
79 pol1rms = scan.rms(all=False) # returns rms for beam=0
80 # if=0, pol=1
81 """
82 self.setbeam(thebeam)
83 self.setpol(thepol)
84 self.setif(theif)
85 return
86
87 def get_selection(self):
88 i = self.getbeam()
89 j = self.getif()
90 k = self.getpol()
91 out = 'Beam=%d IF=%d Pol=%d '% (i,j,k)
92 print out
93 return i,j,k
94
95 def rms(self,mask=None, all=True):
96 """
97 Determine the root mean square of the current beam/if/pol
98 Takes a 'mask' as an optional parameter to specify which
99 channels should be excluded.
100 Parameters:
101 mask: an optional mask specifying where the rms
102 should be determined.
103 all: optional flag to show all or a selected
104 spectrum of Beam/IF/Pol
105
106 Example:
107 scan.setuint('channel')
108 msk = scan.create_mask([100,200],[500,600])
109 scan.rms(mask=m)
110 """
111 from asap._asap import rms as _rms
112 if mask == None:
113 mask = ones(self.nchan())
114 if all:
115 out = ''
116 tmp = []
117 for i in range(self.nbeam()):
118 self.setbeam(i)
119 for j in range(self.nif()):
120 self.setif(j)
121 for k in range(self.npol()):
122 self.setpol(k)
123 rmsval = _rms(self,mask)
124 tmp.append(rmsval)
125 out += 'Beam[%d], IF[%d], Pol[%d] = %3.3f\n' % (i,j,k,rmsval)
126 print out
127 return tmp
128
129 else:
130 i = self.getbeam()
131 j = self.getif()
132 k = self.getpol()
133 rmsval = _rms(self,mask)
134 out = 'Beam[%d], IF[%d], Pol[%d] = %3.3f' % (i,j,k,rmsval)
135 print out
136 return rmsval
137
138 def get_tsys(self, all=True):
139 if all:
140 tmp = []
141 out = ''
142 for i in range(self.nbeam()):
143 self.setbeam(i)
144 for j in range(self.nif()):
145 self.setif(j)
146 for k in range(self.npol()):
147 self.setpol(k)
148 ts = self.gettsys()
149 tmp.append(ts)
150 out += 'TSys: Beam[%d], IF[%d], Pol[%d] = %3.3f\n' % (i,j,k,ts)
151 print out
152 return tmp
153 else:
154 i = self.getbeam()
155 j = self.getif()
156 k = self.getpol()
157 ts = self.gettsys()
158 out = 'TSys: Beam[%d], IF[%d], Pol[%d] = %3.3f' % (i,j,k,ts)
159 print out
160 return ts
161
162 def set_unit(self, unit='channel'):
163 """
164 Set the unit for all following operations on this scantable
165 Parameters:
166 unit: optional unit, default is 'channel'
167 one of 'GHz','MHz','km/s','channel'
168 """
169 units = ['GHz','MHz','km/s','channel','pixel','']
170 if unit in units:
171 if unit in ['','pixel']:
172 unit = 'channel'
173 self._unit = unit
174 else:
175 print "Invalid unit given, please use one of:"
176 print units
177
178 def create_mask(self, *args):
179 """
180 Compute and return a mask based on [min,max] windows.
181 Parameters:
182 [min,max],[min2,max2],...
183 Pairs of start/end points specifying the regions
184 to be masked
185 Example:
186 scan.setunit('channel')
187 msk = scan.set_mask([400,500],[800,900])
188 masks the regions between 400 and 500
189 and 800 and 900 in the unit 'channel'
190 """
191 print "The current mask window unit is", self._unit
192 n = self.nchan()
193 if self._unit == 'channel':
194 data = range(n)
195 else:
196 data = self.getabscissa(unit=self._unit)
197 msk = ones(n)
198 for window in args:
199 if (len(window) != 2 or window[0] > window[1] ):
200 print "A window needs to be defined as [min,max]"
201 return
202 for i in range(n):
203 if data[i] > window[0] and data[i] < window[1]:
204 msk[i] = 0
205 return msk
206 def set_restfrequencies(self, freqs, unit='Hz'):
207 """
208 Set the restfrequency(s) for this scantable.
209 Parameters:
210 freqs: one or more frequencies
211 unit: optional 'unit', default 'Hz'
212 Example:
213 scan.set_restfrequencies([1000000000.0])
214 """
215 self.setrestfreqs(freqs, unit)
216 return
217
218 def flag_spectrum(self, thebeam, theif, thepol):
219 """
220 This flags a selected spectrum in the scan 'for good'.
221 USE WITH CARE - not reversible.
222 Use masks for non-permanent exclusion of channels.
223 Parameters:
224 thebeam,theif,thepol: all have to be explicitly
225 specified
226 Example:
227 scan.flag_spectrum(0,0,1)
228 flags the spectrum for Beam=0, IF=0, Pol=1
229 """
230 if (thebeam < self.nbeam() and theif < self.nif() and thepol < self.npol()):
231 stable.setbeam(thebeam)
232 stable.setif(theif)
233 stable.setpol(thepol)
234 stable._flag(self)
235 else:
236 print "Please specify a valid (Beam/IF/Pol)"
237 return
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