How to show a dictionary sorted on a value within its data?

cl at cl at
Wed Oct 1 11:58:36 CEST 2014

I have a dictionary as follows:-

u'StarterAmps1': Row(id=4, ain=u'AIN3', name=u'StarterAmps1', conv=6834.374834509803, Description=u'Starter Amps'), 
u'LeisureVolts': Row(id=1, ain=u'AIN0', name=u'LeisureVolts', conv=29.01374215995874, Description=u'Leisure Volts'),
u'RudderPos': Row(id=6, ain=u'AIN5', name=u'RudderPos', conv=0.028125, Description=u'Rudder Position'),
u'xx': Row(id=7, ain=u'AIN6', name=u'xx', conv=0.028125, Description=u''),
u'LeisureAmps1': Row(id=3, ain=u'AIN2', name=u'LeisureAmps1', conv=32.727273081945, Description=u'Leisure Amps'),
u'StarterVolts': Row(id=2, ain=u'AIN1', name=u'StarterVolts', conv=28.94469628911757, Description=u'Starter Volts')

I want to output a menu to a user comprising some parts of the
dictionary (ain and Description) sorted by ain.

Is there some incantation of sorted() that will do what I want?  I
can't quite fathom out the 'key=' parameter needed to sort it by the
tuple item.  Maybe I need a cmp= ?

E.g. I want to do something like:-

    for meas in sorted(adc.cfg, key=???):
        print(adc.cfg[meas].ain, adc.cfg[meas].Description)

What's needed in the ???

Chris Green

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