optparse with numpy.array?

James Mills prologic at shortcircuit.net.au
Tue Jan 27 07:07:32 CET 2009

On Tue, Jan 27, 2009 at 4:01 PM, Johan Ekh <ekh.johan at gmail.com> wrote:
> Thank you James,
> but I just can't optparse to accept an array, only integers, floats ans
> strings.
> My code looks like this
> from optparse import OptionParser
> parser = OptionParser()
> parser.add_option('-t', '--dt', action='store', type='float', dest='dt_i',
> default=0.1, help='time increment where lsoda saves results')
> parser.add_option('-T', '--tstop', action='store', type='float',
> dest='tstop_i', default=1.0, help='duration of the solution')
> parser.add_option('-m', '--mass_vector', action='store', type='float',
> dest='m_i', default=[1.0, 1.0], help='vector with lumped masses')
> op, args = parser.parse_args(sys.argv[1:])
> I want this to work for m_i = array([1.0, 2.0, 3.0]) but the optparse
> complains that m_i is not a float.

What you want to do is accept a string as an
argument to -m/--mass_vector and parse
this string into a list.

For example:

parser.add_option('-m', '--mass_vector', action='store',dest='m_i',
default=None, help='vector with lumped masses')
op, args = parser.parse_args(sys.argv[1:])

if op.m_i is None:
   m_i = [1.0, 1.0]
   xs = m_i.split(",")
   m_i = [float(x.strip()) for x in xs]

Of course be aware that this code does no error
checking and if you pass in rubbish, it will likely
throw an exception.


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