[Kimchi-devel] [PATCH 1/2] Add function to convert data sizes
Paulo Ricardo Paz Vital
pvital at gmail.com
Tue Mar 3 08:16:12 UTC 2015
On Mon, 2015-03-02 at 13:45 -0300, Crístian Viana wrote:
> The new function "kimchi.utils.convert_data_size" can be used to convert
> values from different units, e.g. converting 5 GiB to MiB, 1 GiB to B.
>
> Signed-off-by: Crístian Viana <vianac at linux.vnet.ibm.com>
> ---
> src/kimchi/i18n.py | 2 +
> src/kimchi/utils.py | 145 ++++++++++++++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 147 insertions(+)
>
> diff --git a/src/kimchi/i18n.py b/src/kimchi/i18n.py
> index 2af0be6..df5422f 100644
> --- a/src/kimchi/i18n.py
> +++ b/src/kimchi/i18n.py
> @@ -267,6 +267,8 @@ messages = {
> "KCHUTILS0001E": _("Invalid URI %(uri)s"),
> "KCHUTILS0002E": _("Timeout while running command '%(cmd)s' after %(seconds)s seconds"),
> "KCHUTILS0003E": _("Unable to choose a virtual machine name"),
> + "KCHUTILS0004E": _("Invalid data value '%(value)s'"),
> + "KCHUTILS0005E": _("Invalid data unit '%(unit)s'"),
>
> "KCHVMSTOR0002E": _("Invalid storage type. Types supported: 'cdrom', 'disk'"),
> "KCHVMSTOR0003E": _("The path '%(value)s' is not a valid local/remote path for the device"),
> diff --git a/src/kimchi/utils.py b/src/kimchi/utils.py
> index fc5245f..a04d3cf 100644
> --- a/src/kimchi/utils.py
> +++ b/src/kimchi/utils.py
> @@ -388,3 +388,148 @@ def get_unique_file_name(all_names, name):
> max_num = max(max_num, int(match.group(re_group_num)))
>
> return u'%s (%d)' % (name, max_num + 1)
> +
> +
> +def convert_data_size(value, src_unit, dst_unit=None):
s/src_unit/src_unit=None
As explained below, both second and third arguments can be None and then
automatically converted to use DEFAULT_UNIT.
I tried "convert_data_size(4)" and got the error:
TypeError: convert_data_size() takes at least 2 arguments (1 given)
> + """Convert a data value from one unit to another unit
> + (e.g. 'MiB' -> 'GiB').
> +
> + The data units supported by this function are made up of one prefix and one
> + suffix, both optional. The valid prefixes are those defined in the SI
> + (i.e. metric system) and those defined by the IEC, and the valid suffixes
> + indicate if the base unit is bit or byte. Take a look at the tables below
> + for the possible values:
> +
> + Prefixes:
> +
> + ================================== ===================================
> + PREFIX (SI) | DESCRIPTION | VALUE PREFIX (IEC) | DESCRIPTION | VALUE
> + ================================== ===================================
> + k | kilo | 1000 Ki | kibi | 1024
> + ---------------------------------- -----------------------------------
> + M | mega | 1000^2 Mi | mebi | 1024^2
> + ---------------------------------- -----------------------------------
> + G | giga | 1000^3 Gi | gibi | 1024^3
> + ---------------------------------- -----------------------------------
> + T | tera | 1000^4 Ti | tebi | 1024^4
> + ---------------------------------- -----------------------------------
> + P | peta | 1000^5 Pi | pebi | 1024^5
> + ---------------------------------- -----------------------------------
> + E | exa | 1000^6 Ei | exbi | 1024^6
> + ---------------------------------- -----------------------------------
> + Z | zetta | 1000^7 Zi | zebi | 1024^7
> + ---------------------------------- -----------------------------------
> + Y | yotta | 1000^8 Yi | yobi | 1024^8
> + ================================== ===================================
> +
> + Suffixes:
> +
> + ====================
> + SUFFIX | DESCRIPTION
> + ====================
> + b | bit
> + --------------------
> + B | byte
> + ====================
> +
> + See http://en.wikipedia.org/wiki/Binary_prefix for more details on
> + those units.
> +
> + If a wrong prefix or suffix is provided, an error will be raised.
> +
> + Examples:
> + convert_data_size(5, 'MiB', 'KiB') -> 5120.0
> + convert_data_size(5, 'MiB', 'M') -> 5.24288
> + convert_data_size(5, 'MiB', 'GiB') -> 0.0048828125
> + convert_data_size(5, 'MiB', 'Tb') -> 4.194304e-05
> + convert_data_size(5, 'MiB') -> 5242880.0
> + convert_data_size(5, 'mib') -> #ERROR# (invalid src_unit)
> +
> + Parameters:
> + value -- the value to be converted, in the unit specified by 'src_unit'.
> + this parameter can be of any type which can be cast to float
> + (e.g. int, float, str).
> + src_unit -- the unit of 'value', as described above.
> + if 'src_unit' is empty, the unit 'B' (byte) will be used.
> + dst_unit -- the unit of the return value.
> + if 'dst_unit' is empty, the unit 'B' (byte) will be used.
> +
> + Return:
> + A float number representing 'value' ('src_unit') converted to 'dst_unit'.
> + """
> + SI_PREFIXES = ['k', 'M', 'G', 'T', 'P', 'E', 'Z', 'Y']
I guess you can add a new line here, as you did between
SUFFIXES_WITH_MULT and DEFAULT_SUFFIX.
> + # The IEC prefixes are the equivalent SI prefixes + 'i'
> + # but, exceptionally, 'k' becomes 'Ki' instead of 'ki'.
> + IEC_PREFIXES = map(lambda p: 'Ki' if p == 'k' else p + 'i', SI_PREFIXES)
New line here.
> + PREFIXES_BY_BASE = {1000: SI_PREFIXES,
> + 1024: IEC_PREFIXES}
> +
> + SUFFIXES_WITH_MULT = {'b': 1,
> + 'B': 8}
> + DEFAULT_SUFFIX = 'B'
> +
> + DEFAULT_UNIT = 'B'
> +
> + # set the default units
> + if not src_unit:
> + src_unit = DEFAULT_UNIT
> + if not dst_unit:
> + dst_unit = DEFAULT_UNIT
> +
> + # set the default suffix
> + if src_unit[-1] not in SUFFIXES_WITH_MULT:
> + src_unit += DEFAULT_SUFFIX
> + if dst_unit[-1] not in SUFFIXES_WITH_MULT:
> + dst_unit += DEFAULT_SUFFIX
> +
> + # split prefix and suffix for better parsing
> + src_p = src_unit[:-1]
> + src_s = src_unit[-1]
> + dst_p = dst_unit[:-1]
> + dst_s = dst_unit[-1]
> +
> + # validate parameters
> + try:
> + value = float(value)
> + except TypeError:
> + raise InvalidParameter('KCHUTILS0004E', {'value': value})
> + if src_p != '' and src_p not in (SI_PREFIXES + IEC_PREFIXES):
> + raise InvalidParameter('KCHUTILS0005E', {'unit': src_unit})
> + if src_s not in SUFFIXES_WITH_MULT:
> + raise InvalidParameter('KCHUTILS0005E', {'unit': src_unit})
> + if dst_p != '' and dst_p not in (SI_PREFIXES + IEC_PREFIXES):
> + raise InvalidParameter('KCHUTILS0005E', {'unit': dst_unit})
> + if dst_s not in SUFFIXES_WITH_MULT:
> + raise InvalidParameter('KCHUTILS0005E', {'unit': dst_unit})
> +
> + # convert 'value' to the most basic unit (bits)...
> + bits = value
> +
> + for suffix, mult in SUFFIXES_WITH_MULT.iteritems():
> + if src_s == suffix:
> + bits *= mult
> + break
> +
> + if src_p != '':
> + for base, prefixes in PREFIXES_BY_BASE.iteritems():
> + for i, p in enumerate(prefixes):
> + if src_p == p:
> + bits *= base**(i + 1)
> + break
> +
> + # ...then convert the value in bits to the destination unit
> + ret = bits
> +
> + for suffix, mult in SUFFIXES_WITH_MULT.iteritems():
> + if dst_s == suffix:
> + ret /= float(mult)
> + break
> +
> + if dst_p != '':
> + for base, prefixes in PREFIXES_BY_BASE.iteritems():
> + for i, p in enumerate(prefixes):
> + if dst_p == p:
> + ret /= float(base)**(i + 1)
> + break
> +
> + return ret
--
Paulo Ricardo Paz Vital <pvital at gmail.com>
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