| 1 | from scantable import scantable
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| 2 |
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| 3 | def average_time(*args, **kwargs):
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| 4 | """
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| 5 | Return the (time) average of a scan or list of scans. [in channels only]
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| 6 | Parameters:
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| 7 | one scan or comma separated scans
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| 8 | mask: an optional mask (only used for 'var' and 'tsys' weighting)
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| 9 | scanav: False (default) averages all scans together,
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| 10 | True averages each scan separately
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| 11 | weight: Weighting scheme. 'none' (default), 'var' (variance
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| 12 | weighted), 'tsys'
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| 13 | Example:
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| 14 | # return a time averaged scan from scana and scanb
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| 15 | # without using a mask
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| 16 | scanav = average_time(scana,scanb)
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| 17 | # return the (time) averaged scan, i.e. the average of
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| 18 | # all correlator cycles
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| 19 | scanav = average_time(scan)
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| 20 |
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| 21 | """
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| 22 | scanAv = False
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| 23 | if kwargs.has_key('scanav'):
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| 24 | scanAv = kwargs.get('scanav')
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| 25 | #
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| 26 | weight = 'none'
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| 27 | if kwargs.has_key('weight'):
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| 28 | weight = kwargs.get('weight')
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| 29 | #
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| 30 | mask = ()
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| 31 | if kwargs.has_key('mask'):
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| 32 | mask = kwargs.get('mask')
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| 33 | #
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| 34 | lst = tuple(args)
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| 35 | from asap._asap import average as _av
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| 36 | for s in lst:
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| 37 | if not isinstance(s,scantable):
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| 38 | print "Please give a list of scantables"
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| 39 | return
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| 40 | return scantable(_av(lst, mask, scanAv, weight))
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| 41 |
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| 42 | def quotient(source, reference, preserve=True):
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| 43 | """
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| 44 | Return the quotient of a 'source' (signal) scan and a 'reference' scan.
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| 45 | The reference can have just one row, even if the signal has many. Otherwise
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| 46 | they must have the same number of rows.
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| 47 | Parameters:
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| 48 | source: the 'on' scan
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| 49 | reference: the 'off' scan
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| 50 | preserve: you can preserve (default) the continuum or
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| 51 | remove it. The equations used are
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| 52 | preserve - Output = Tref * (sig/ref) - Tref
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| 53 | remove - Output = Tref * (sig/ref) - Tsig
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| 54 | """
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| 55 | from asap._asap import quotient as _quot
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| 56 | return scantable(_quot(source, reference, preserve))
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| 57 |
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| 58 | def b_operate(left, right, op='add'):
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| 59 | """
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| 60 | Apply simple mathematical binary operations to two
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| 61 | scan tables, returning the result in a new scan table.
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| 62 | The operation is applied to both the correlations and the TSys data
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| 63 | Parameters:
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| 64 | left: the 'left' scan
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| 65 | right: the 'right' scan
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| 66 | op: the operation: 'add' (default), 'sub', 'mul', 'div'
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| 67 | """
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| 68 | from asap._asap import b_operate as _bop
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| 69 | return scantable(_bop(left, right, op))
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| 70 |
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| 71 | def scale(scan, factor, insitu=False, all=True):
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| 72 | """
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| 73 | Return a scan where all spectra are scaled by the give 'factor'
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| 74 | Parameters:
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| 75 | scan: a scantable
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| 76 | factor: the scaling factor
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| 77 | insitu: if False (default) a new scantable is returned.
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| 78 | Otherwise, the scaling is done in-situ
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| 79 | all: if True (default) apply to all spectra. Otherwise
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| 80 | apply only to the selected (beam/pol/if)spectra only
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| 81 | """
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| 82 | if not insitu:
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| 83 | from asap._asap import scale as _scale
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| 84 | return scantable(_scale(scan, factor, all))
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| 85 | else:
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| 86 | from asap._asap import scale_insitu as _scale
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| 87 | _scale(scan, factor, all)
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| 88 | return
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| 89 |
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| 90 |
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| 91 | def add(scan, offset, insitu=False, all=True):
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| 92 | """
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| 93 | Return a scan where all spectra have the offset added
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| 94 | Parameters:
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| 95 | scan: a scantable
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| 96 | offset: the offset
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| 97 | insitu: if False (default) a new scantable is returned.
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| 98 | Otherwise, the addition is done in-situ
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| 99 | all: if True (default) apply to all spectra. Otherwise
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| 100 | apply only to the selected (beam/pol/if)spectra only
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| 101 | """
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| 102 | if not insitu:
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| 103 | from asap._asap import add as _add
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| 104 | return scantable(_add(scan, offset, all))
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| 105 | else:
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| 106 | from asap._asap import add_insitu as _add
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| 107 | _add(scan, offset, all)
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| 108 | return
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| 109 |
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| 110 | def convert_flux(scan, area, eta=1.0, insitu=False, all=True):
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| 111 | """
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| 112 | Return a scan where all spectra are converted to either Jansky or Kelvin
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| 113 | depending upon the flux units of the scan table.
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| 114 | Parameters:
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| 115 | scan: a scantable
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| 116 | area: the illuminated area of the telescope (m**2)
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| 117 | eta: The efficiency of the telescope (default 1.0)
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| 118 | insitu: if False (default) a new scantable is returned.
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| 119 | Otherwise, the conversion is done in-situ
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| 120 | all: if True (default) apply to all spectra. Otherwise
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| 121 | apply only to the selected (beam/pol/if)spectra only
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| 122 | """
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| 123 | if not insitu:
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| 124 | from asap._asap import convertflux as _convert
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| 125 | return scantable(_convert(scan, area, eta, all))
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| 126 | else:
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| 127 | from asap._asap import convertflux_insitu as _convert
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| 128 | _convert(scan, area, eta, all)
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| 129 | return
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| 130 |
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| 131 | def gain_el(scan, poly=None, filename="", method="linear", insitu=False, all=True):
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| 132 | """
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| 133 | Return a scan after applying a gain-elevation correction. The correction
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| 134 | can be made via either a polynomial or a table-based interpolation
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| 135 | (and extrapolation if necessary).
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| 136 | You specify polynomial coefficients, an ascii table or neither.
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| 137 | If you specify neither, then a polynomial correction will be made
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| 138 | with built in coefficients known for certain telescopes (an error will
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| 139 | occur if the instrument is not known).
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| 140 | Parameters:
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| 141 | scan: a scantable
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| 142 | poly: Polynomial coefficients (default None) to compute a gain-elevation
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| 143 | correction as a function of elevation (in degrees).
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| 144 | filename: The name of an ascii file holding correction factors.
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| 145 | The first row of the ascii file must give the column
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| 146 | names and these MUST include columns
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| 147 | "ELEVATION" (degrees) and "FACTOR" (multiply data by this) somewhere.
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| 148 | The second row must give the data type of the column. Use 'R' for
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| 149 | Real and 'I' for Integer. An example file would be:
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| 150 |
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| 151 | TIME ELEVATION FACTOR
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| 152 | R R R
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| 153 | 0.1 0 1.5
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| 154 | 0.2 20 1.4
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| 155 | 0.3 40 1.3
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| 156 | 0.4 60 1.2
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| 157 | 0.5 80 1.1
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| 158 | 0.6 90 1.0
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| 159 | method: Interpolation method when correcting from a table. Values
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| 160 | are "nearest", "linear" (default), "cubic" and "spline"
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| 161 | insitu: if False (default) a new scantable is returned.
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| 162 | Otherwise, the conversion is done in-situ
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| 163 | all: if True (default) apply to all spectra. Otherwise
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| 164 | apply only to the selected (beam/pol/if)spectra only
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| 165 | """
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| 166 | if poly is None:
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| 167 | poly = ()
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| 168 | if not insitu:
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| 169 | from asap._asap import gainel as _gainEl
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| 170 | return scantable(_gainEl(scan, poly, filename, method, all))
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| 171 | else:
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| 172 | from asap._asap import gainel_insitu as _gainEl
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| 173 | _gainEl(scan, poly, filename, method, all)
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| 174 | return
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| 175 |
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| 176 | def opacity(scan, tau, insitu=False, all=True):
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| 177 | """
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| 178 | Return a scan after applying an opacity correction.
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| 179 | Parameters:
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| 180 | scan: a scantable
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| 181 | tau: Opacity from which the correction factor is exp(tau*ZD)
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| 182 | where ZD is the zenith-distance
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| 183 | insitu: if False (default) a new scantable is returned.
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| 184 | Otherwise, the conversion is done in-situ
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| 185 | all: if True (default) apply to all spectra. Otherwise
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| 186 | apply only to the selected (beam/pol/if)spectra only
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| 187 | """
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| 188 | if not insitu:
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| 189 | from asap._asap import opacity as _opacity
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| 190 | return scantable(_opacity(scan, tau, all))
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| 191 | else:
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| 192 | from asap._asap import opacity_insitu as _opacity
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| 193 | _opacity(scan, tau, all)
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| 194 | return
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| 195 |
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| 196 | def bin(scan, width=5, insitu=False):
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| 197 | """
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| 198 | Return a scan where all spectra have been binned up
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| 199 | width: The bin width (default=5) in pixels
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| 200 | insitu: if False (default) a new scantable is returned.
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| 201 | Otherwise, the addition is done in-situ
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| 202 | """
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| 203 | if not insitu:
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| 204 | from asap._asap import bin as _bin
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| 205 | return scantable(_bin(scan, width))
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| 206 | else:
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| 207 | from asap._asap import bin_insitu as _bin
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| 208 | _bin(scan, width)
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| 209 | return
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| 210 |
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| 211 | def average_pol(scan, mask=None, insitu=False):
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| 212 | """
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| 213 | Average the Polarisations together.
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| 214 | Parameters:
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| 215 | scan: The scantable
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| 216 | mask: An optional mask defining the region, where the
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| 217 | averaging will be applied. The output will have all
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| 218 | specified points masked.
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| 219 | insitu: If False (default) a new scantable is returned.
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| 220 | Otherwise, the averaging is done in-situ
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| 221 | Example:
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| 222 | polav = average_pols(myscan)
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| 223 | """
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| 224 | if mask is None:
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| 225 | mask = ()
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| 226 | if not insitu:
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| 227 | from asap._asap import averagepol as _avpol
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| 228 | return scantable(_avpol(scan, mask))
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| 229 | else:
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| 230 | from asap._asap import averagepol_insitu as _avpol
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| 231 | _avpol(scan, mask)
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| 232 | return
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| 233 |
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| 234 | def smooth(scan, kernel="hanning", width=5.0, insitu=False, all=True):
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| 235 | """
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| 236 | Smooth the spectrum by the specified kernel (conserving flux).
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| 237 | Parameters:
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| 238 | scan: The input scan
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| 239 | kernel: The type of smoothing kernel. Select from
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| 240 | 'hanning' (default), 'gaussian' and 'boxcar'.
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| 241 | The first three characters are sufficient.
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| 242 | width: The width of the kernel in pixels. For hanning this is
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| 243 | ignored otherwise it defauls to 5 pixels.
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| 244 | For 'gaussian' it is the Full Width Half
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| 245 | Maximum. For 'boxcar' it is the full width.
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| 246 | insitu: If False (default) a new scantable is returned.
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| 247 | Otherwise, the scaling is done in-situ
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| 248 | all: If True (default) apply to all spectra. Otherwise
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| 249 | apply only to the selected (beam/pol/if)spectra only
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| 250 | Example:
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| 251 | none
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| 252 | """
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| 253 | if not insitu:
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| 254 | from asap._asap import smooth as _smooth
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| 255 | return scantable(_smooth(scan,kernel,width,all))
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| 256 | else:
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| 257 | from asap._asap import smooth_insitu as _smooth
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| 258 | _smooth(scan,kernel,width,all)
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| 259 | return
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| 260 |
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| 261 | def poly_baseline(scan, mask=None, order=0):
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| 262 | """
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| 263 | Return a scan which has been baselined (all rows) by a polynomial.
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| 264 | Parameters:
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| 265 | scan: a scantable
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| 266 | mask: an optional mask
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| 267 | order: the order of the polynomial (default is 0)
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| 268 | Example:
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| 269 | # return a scan baselined by a third order polynomial,
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| 270 | # not using a mask
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| 271 | bscan = poly_baseline(scan, order=3)
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| 272 | """
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| 273 | from asap.asapfitter import fitter
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| 274 | if mask is None:
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| 275 | from numarray import ones
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| 276 | mask = tuple(ones(scan.nchan()))
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| 277 | f = fitter()
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| 278 | f._verbose(True)
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| 279 | f.set_scan(scan, mask)
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| 280 | f.set_function(poly=order)
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| 281 | sf = f.auto_fit()
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| 282 | return sf
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