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quanta.quantity - Function

1.5.1 make a quantity from a string or from a numeric value and a unit string

Description

quantity makes a quantity from a string, or from a value and a string. Note that a function unit exists which is a synonym for quantity. If only a string is given, it can be a scalar string. The result will be a scalar quantity.

If a numeric value and a unit string are given, the numeric value can be any numeric type, and can also be a vector of numeric values. print qa.map() to get a list of recognized units. ’d’ is usually days, but can be degrees (see example).

Arguments

 Inputs v quantity or numeric or string to convert to quantity allowed: variant Default: unitname unit string if v numeric allowed: string Default:
Returns
record

Example

"""
#
print "\t----\t quantity Ex 1 \t----"
tu = qa.quantity(’1Jy’) # make quantity
print tu
#{’value’: 1.0, ’unit’: ’Jy’}
print qa.quantity(tu) # also accepts a quantity
#{’value’: 1.0, ’unit’: ’Jy’}
tu = qa.unit(’1Jy’) # make quantity with synonym
print tu
#{’value’: 1.0, ’unit’: ’Jy’}
print qa.quantity(-1.3, ’Jy’) # make quantity with separate value
#{’value’: -1.3, ’unit’: ’Jy’}
q1 = qa.quantity([8.57132661e+09, 1.71426532e+10], ’km/s’) # Composite unit
print q1
#{’value’: array([  8.57132661e+09,   1.71426532e+10]), ’unit’: ’km/s’}
q = qa.quantity(’5d’); print q
#{’value’: 5.0, ’unit’: ’d’}            # d = days
q = qa.quantity(’5 d’); print q
#{’value’: 5.0, ’unit’: ’d’}            # even if there’s a space, as of 5/28/09
q = qa.quantity(’5d30m’); print q
#{’value’: 5.5, ’unit’: ’deg’}          # Unless followed by an m!
qa.quantity(’5d30s’)                    # WRONG
# {’unit’: ’d30s’, ’value’: 5.0}        # I told you...
qa.quantity(’5d0m30s’)                  # OK
# {’unit’: ’deg’, ’value’: 5.0083333333333337}
"""

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