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#
# Copyright 2003 Free Software Foundation, Inc.
#
# This file is part of GNU Radio
#
# GNU Radio is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 3, or (at your option)
# any later version.
#
# GNU Radio is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with GNU Radio; see the file COPYING. If not, write to
# the Free Software Foundation, Inc., 51 Franklin Street,
# Boston, MA 02110-1301, USA.
#
"""
Display numbers as strings using engineering notation.
"""
from __future__ import unicode_literals
import six
scale_factor = {}
scale_factor['E'] = 1e18
scale_factor['P'] = 1e15
scale_factor['T'] = 1e12
scale_factor['G'] = 1e9
scale_factor['M'] = 1e6
scale_factor['k'] = 1e3
scale_factor['m'] = 1e-3
scale_factor['u'] = 1e-6
scale_factor['n'] = 1e-9
scale_factor['p'] = 1e-12
scale_factor['f'] = 1e-15
scale_factor['a'] = 1e-18
def num_to_str (n, precision=6):
'''Convert a number to a string in engineering notation. E.g., 5e-9 -> 5n'''
m = abs(n)
format_spec = '%.' + repr(int(precision)) + 'g'
if m >= 1e9:
return '%sG' % float(format_spec % (n * 1e-9))
elif m >= 1e6:
return '%sM' % float(format_spec % (n * 1e-6))
elif m >= 1e3:
return '%sk' % float(format_spec % (n * 1e-3))
elif m >= 1:
return '%s' % float(format_spec % (n))
elif m >= 1e-3:
return '%sm' % float(format_spec % (n * 1e3))
elif m >= 1e-6:
return '%su' % float(format_spec % (n * 1e6))
elif m >= 1e-9:
return '%sn' % float(format_spec % (n * 1e9))
elif m >= 1e-12:
return '%sp' % float(format_spec % (n * 1e12))
elif m >= 1e-15:
return '%sf' % float(format_spec % (n * 1e15))
else:
return '%s' % float(format_spec % (n))
def str_to_num (value):
'''Convert a string in engineering notation to a number. E.g., '15m' -> 15e-3'''
try:
if not isinstance(value, six.string_types):
raise TypeError("Value must be a string")
scale = 1.0
suffix = value[-1]
if suffix in scale_factor:
return float (value[0:-1]) * scale_factor[suffix]
return float (value)
except (TypeError, KeyError, ValueError):
raise ValueError (
"Invalid engineering notation value: %r" % (value,))
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