source: trunk/python/asapmath.py@ 364

Last change on this file since 364 was 359, checked in by kil064, 20 years ago

change interface to convert_flux

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File size: 15.8 KB
Line 
1from scantable import scantable
2from asap import rcParams
3
4def average_time(*args, **kwargs):
5 """
6 Return the (time) average of a scan or list of scans. [in channels only]
7 The cursor of the output scan is set to 0
8 Parameters:
9 one scan or comma separated scans
10 mask: an optional mask (only used for 'var' and 'tsys' weighting)
11 scanav: False (default) averages all scans together,
12 True averages each scan separately
13 weight: Weighting scheme. 'none' (default), 'var' (variance
14 weighted), 'tsys'
15 Example:
16 # return a time averaged scan from scana and scanb
17 # without using a mask
18 scanav = average_time(scana,scanb)
19 # return the (time) averaged scan, i.e. the average of
20 # all correlator cycles
21 scanav = average_time(scan)
22
23 """
24 scanAv = False
25 if kwargs.has_key('scanav'):
26 scanAv = kwargs.get('scanav')
27
28 weight = 'none'
29 if kwargs.has_key('weight'):
30 weight = kwargs.get('weight')
31
32 mask = ()
33 if kwargs.has_key('mask'):
34 mask = kwargs.get('mask')
35
36 lst = tuple(args)
37 from asap._asap import average as _av
38 for s in lst:
39 if not isinstance(s,scantable):
40 print "Please give a list of scantables"
41 return
42 return scantable(_av(lst, mask, scanAv, weight))
43
44def quotient(source, reference, preserve=True):
45 """
46 Return the quotient of a 'source' (signal) scan and a 'reference' scan.
47 The reference can have just one row, even if the signal has many. Otherwise
48 they must have the same number of rows.
49 The cursor of the output scan is set to 0
50 Parameters:
51 source: the 'on' scan
52 reference: the 'off' scan
53 preserve: you can preserve (default) the continuum or
54 remove it. The equations used are
55 preserve - Output = Tref * (sig/ref) - Tref
56 remove - Output = Tref * (sig/ref) - Tsig
57 """
58 from asap._asap import quotient as _quot
59 return scantable(_quot(source, reference, preserve))
60
61def simple_math(left, right, op='add', tsys=True):
62 """
63 Apply simple mathematical binary operations to two
64 scan tables, returning the result in a new scan table.
65 The operation is applied to both the correlations and the TSys data
66 The cursor of the output scan is set to 0
67 Parameters:
68 left: the 'left' scan
69 right: the 'right' scan
70 op: the operation: 'add' (default), 'sub', 'mul', 'div'
71 tsys: if True (default) then apply the operation to Tsys
72 as well as the data
73 """
74 if not isinstance(left,scantable) and not isinstance(right,scantable):
75 print "Please provide two scantables as input"
76 return
77 from asap._asap import b_operate as _bop
78 return scantable(_bop(left, right, op, tsys))
79
80def scale(scan, factor, insitu=None, allaxes=None, tsys=True):
81 """
82 Return a scan where all spectra are scaled by the give 'factor'
83 Parameters:
84 scan: a scantable
85 factor: the scaling factor
86 insitu: if False a new scantable is returned.
87 Otherwise, the scaling is done in-situ
88 The default is taken from .asaprc (False)
89 allaxes: if True apply to all spectra. Otherwise
90 apply only to the selected (beam/pol/if)spectra only.
91 The default is taken from .asaprc (True)
92 tsys: if True (default) then apply the operation to Tsys
93 as well as the data
94 """
95 if allaxes is None: allaxes = rcParams['scantable.allaxes']
96 if insitu is None: insitu = rcParams['insitu']
97 if not insitu:
98 from asap._asap import scale as _scale
99 return scantable(_scale(scan, factor, allaxes, tsys))
100 else:
101 from asap._asap import scale_insitu as _scale
102 _scale(scan, factor, allaxes, tsys)
103 return
104
105
106def add(scan, offset, insitu=None, allaxes=None):
107 """
108 Return a scan where all spectra have the offset added
109 Parameters:
110 scan: a scantable
111 offset: the offset
112 insitu: if False a new scantable is returned.
113 Otherwise, the scaling is done in-situ
114 The default is taken from .asaprc (False)
115 allaxes: if True apply to all spectra. Otherwise
116 apply only to the selected (beam/pol/if)spectra only
117 The default is taken from .asaprc (True)
118 """
119 if allaxes is None: allaxes = rcParams['scantable.allaxes']
120 if insitu is None: insitu = rcParams['insitu']
121 if not insitu:
122 from asap._asap import add as _add
123 return scantable(_add(scan, offset, allaxes))
124 else:
125 from asap._asap import add_insitu as _add
126 _add(scan, offset, allaxes)
127 return
128
129def convert_flux(scan, jyperk=None, eta=None, d=None, insitu=None, allaxes=None):
130 """
131 Return a scan where all spectra are converted to either Jansky or Kelvin
132 depending upon the flux units of the scan table. By default the
133 function tries to look the values up internally. If it can't find
134 them (or if you want to over-ride), you must specify EITHER jyperk
135 OR eta (and D which it will try to look up also if you don't
136 set it). jyperk takes precedence if you set both.
137 Parameters:
138 scan: a scantable
139 jyperk: the Jy / K conversion factor
140 eta: the aperture efficiency
141 d: the geomtric diameter (metres)
142 insitu: if False a new scantable is returned.
143 Otherwise, the scaling is done in-situ
144 The default is taken from .asaprc (False)
145 allaxes: if True apply to all spectra. Otherwise
146 apply only to the selected (beam/pol/if)spectra only
147 The default is taken from .asaprc (True)
148 """
149 if allaxes is None: allaxes = rcParams['scantable.allaxes']
150 if insitu is None: insitu = rcParams['insitu']
151 if jyperk is None: jyperk = -1.0
152 if d is None: d = -1.0
153 if eta is None: eta = -1.0
154 if not insitu:
155 from asap._asap import convertflux as _convert
156 return scantable(_convert(scan, d, eta, jyperk, allaxes))
157 else:
158 from asap._asap import convertflux_insitu as _convert
159 _convert(scan, d, eta, jyperk, allaxes)
160 return
161
162def gain_el(scan, poly=None, filename="", method="linear", insitu=None, allaxes=None):
163 """
164 Return a scan after applying a gain-elevation correction. The correction
165 can be made via either a polynomial or a table-based interpolation
166 (and extrapolation if necessary).
167 You specify polynomial coefficients, an ascii table or neither.
168 If you specify neither, then a polynomial correction will be made
169 with built in coefficients known for certain telescopes (an error will
170 occur if the instrument is not known).
171 Parameters:
172 scan: a scantable
173 poly: Polynomial coefficients (default None) to compute a
174 gain-elevation correction as a function of
175 elevation (in degrees).
176 filename: The name of an ascii file holding correction factors.
177 The first row of the ascii file must give the column
178 names and these MUST include columns
179 "ELEVATION" (degrees) and "FACTOR" (multiply data by this)
180 somewhere.
181 The second row must give the data type of the column. Use
182 'R' for Real and 'I' for Integer. An example file
183 would be:
184
185 TIME ELEVATION FACTOR
186 R R R
187 0.1 0 1.5
188 0.2 20 1.4
189 0.3 40 1.3
190 0.4 60 1.2
191 0.5 80 1.1
192 0.6 90 1.0
193 method: Interpolation method when correcting from a table. Values
194 are "nearest", "linear" (default), "cubic" and "spline"
195 insitu: if False a new scantable is returned.
196 Otherwise, the scaling is done in-situ
197 The default is taken from .asaprc (False)
198 allaxes: if True apply to all spectra. Otherwise
199 apply only to the selected (beam/pol/if) spectra only
200 The default is taken from .asaprc (True)
201 """
202 if allaxes is None: allaxes = rcParams['scantable.allaxes']
203 if poly is None:
204 poly = ()
205 if insitu is None: insitu = rcParams['insitu']
206 if not insitu:
207 from asap._asap import gainel as _gainEl
208 return scantable(_gainEl(scan, poly, filename, method, allaxes))
209 else:
210 from asap._asap import gainel_insitu as _gainEl
211 _gainEl(scan, poly, filename, method, allaxes)
212 return
213
214def freq_align(scan, reftime=None, method='cubic', insitu=None):
215 """
216 Return a scan where all rows have been aligned in frequency. The
217 alignment frequency frame (e.g. LSRK) is that set by function
218 set_freqframe.
219 scan: a scantable
220 reftime: reference time to align at. By default, the time of
221 the first row of data is used.
222 method: Interpolation method for regridding the spectra. Choose
223 from "nearest", "linear", "cubic" (default) and "spline"
224 insitu: if False a new scantable is returned.
225 Otherwise, the scaling is done in-situ
226 The default is taken from .asaprc (False)
227 """
228 if reftime is None: reftime = ''
229 if insitu is None: insitu = rcParams['insitu']
230 if not insitu:
231 from asap._asap import freq_align as _align
232 return scantable(_align(scan, reftime, method))
233 else:
234 from asap._asap import freq_align_insitu as _align
235 _align(scan, reftime, method)
236 return
237
238def opacity(scan, tau, insitu=None, allaxes=None):
239 """
240 Return a scan after applying an opacity correction.
241 Parameters:
242 scan: a scantable
243 tau: Opacity from which the correction factor is exp(tau*ZD)
244 where ZD is the zenith-distance
245 insitu: if False a new scantable is returned.
246 Otherwise, the scaling is done in-situ
247 The default is taken from .asaprc (False)
248 allaxes: if True apply to all spectra. Otherwise
249 apply only to the selected (beam/pol/if)spectra only
250 The default is taken from .asaprc (True)
251 """
252 if allaxes is None: allaxes = rcParams['scantable.allaxes']
253 if insitu is None: insitu = rcParams['insitu']
254 if not insitu:
255 from asap._asap import opacity as _opacity
256 return scantable(_opacity(scan, tau, allaxes))
257 else:
258 from asap._asap import opacity_insitu as _opacity
259 _opacity(scan, tau, allaxes)
260 return
261
262def bin(scan, width=5, insitu=None):
263 """
264 Return a scan where all spectra have been binned up
265 width: The bin width (default=5) in pixels
266 insitu: if False a new scantable is returned.
267 Otherwise, the scaling is done in-situ
268 The default is taken from .asaprc (False)
269 """
270 if insitu is None: insitu = rcParams['insitu']
271 if not insitu:
272 from asap._asap import bin as _bin
273 return scantable(_bin(scan, width))
274 else:
275 from asap._asap import bin_insitu as _bin
276 _bin(scan, width)
277 return
278
279def resample(scan, width=5, method='cubic', insitu=None):
280 """
281 Return a scan where all spectra have been binned up
282 width: The bin width (default=5) in pixels
283 method: Interpolation method when correcting from a table. Values
284 are "nearest", "linear", "cubic" (default) and "spline"
285 insitu: if False a new scantable is returned.
286 Otherwise, the scaling is done in-situ
287 The default is taken from .asaprc (False)
288 """
289 if insitu is None: insitu = rcParams['insitu']
290 if not insitu:
291 from asap._asap import resample as _resample
292 return scantable(_resample(scan, method, width))
293 else:
294 from asap._asap import resample_insitu as _resample
295 _resample(scan, method, width)
296 return
297
298def average_pol(scan, mask=None, weight='none', insitu=None):
299 """
300 Average the Polarisations together.
301 The polarisation cursor of the output scan is set to 0
302 Parameters:
303 scan: The scantable
304 mask: An optional mask defining the region, where the
305 averaging will be applied. The output will have all
306 specified points masked.
307 weight: Weighting scheme. 'none' (default), or 'var' (variance
308 weighted)
309 insitu: if False a new scantable is returned.
310 Otherwise, the scaling is done in-situ
311 The default is taken from .asaprc (False)
312 Example:
313 polav = average_pols(myscan)
314 """
315 if mask is None:
316 mask = ()
317 if insitu is None: insitu = rcParams['insitu']
318 if not insitu:
319 from asap._asap import averagepol as _avpol
320 return scantable(_avpol(scan, mask, weight))
321 else:
322 from asap._asap import averagepol_insitu as _avpol
323 _avpol(scan, mask, weight)
324 return
325
326def smooth(scan, kernel="hanning", width=5.0, insitu=None, allaxes=None):
327 """
328 Smooth the spectrum by the specified kernel (conserving flux).
329 Parameters:
330 scan: The input scan
331 kernel: The type of smoothing kernel. Select from
332 'hanning' (default), 'gaussian' and 'boxcar'.
333 The first three characters are sufficient.
334 width: The width of the kernel in pixels. For hanning this is
335 ignored otherwise it defauls to 5 pixels.
336 For 'gaussian' it is the Full Width Half
337 Maximum. For 'boxcar' it is the full width.
338 insitu: if False a new scantable is returned.
339 Otherwise, the scaling is done in-situ
340 The default is taken from .asaprc (False)
341 allaxes: If True (default) apply to all spectra. Otherwise
342 apply only to the selected (beam/pol/if)spectra only
343 The default is taken from .asaprc (True)
344 Example:
345 none
346 """
347 if allaxes is None: allaxes = rcParams['scantable.allaxes']
348 if insitu is None: insitu = rcParams['insitu']
349 if not insitu:
350 from asap._asap import smooth as _smooth
351 return scantable(_smooth(scan,kernel,width,allaxes))
352 else:
353 from asap._asap import smooth_insitu as _smooth
354 _smooth(scan,kernel,width,allaxes)
355 return
356
357def poly_baseline(scan, mask=None, order=0, insitu=None):
358 """
359 Return a scan which has been baselined (all rows) by a polynomial.
360 Parameters:
361 scan: a scantable
362 mask: an optional mask
363 order: the order of the polynomial (default is 0)
364 insitu: if False a new scantable is returned.
365 Otherwise, the scaling is done in-situ
366 The default is taken from .asaprc (False)
367 Example:
368 # return a scan baselined by a third order polynomial,
369 # not using a mask
370 bscan = poly_baseline(scan, order=3)
371 """
372 from asap.asapfitter import fitter
373 if mask is None:
374 from numarray import ones
375 mask = tuple(ones(scan.nchan()))
376 f = fitter()
377 f._verbose(True)
378 f.set_scan(scan, mask)
379 f.set_function(poly=order)
380 sf = f.auto_fit(insitu)
381 return sf
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