def dropout_rate_per_period(data, rule, window_start=None, window_end=None):
"""
Parameters
----------
data : pandas.DataFrame or Series or DatetimeIndex
rule : pandas Offset string (or what ever the `rule` parameter in
pd.Series.resample accepts)
window_start, window_end : pd.Timestamp
The start and end of the window of interest. If this window
is larger than the duration of `data` then gaps will be
appended to the front / back as necessary. If this window
is shorter than the duration of `data` data will be cropped.
Returns
-------
pd.Series
Index is a regular DatetimeIndex with freq=rule and
timezone=data.index.tzinfo
Values are the number of dropped in that time period.
"""
# TODO: this might be a rather nasty hack to fix the circular dependency
from nilmtk.preprocessing.electricity.single import reframe_index
try:
data = data.dropna()
except AttributeError:
# if data is DatetimeIndex then it has no `dropna()` method
pass
sample_period_secs = get_sample_period(data)
n_expected_samples_per_period = (secs_per_period_alias(rule) /
sample_period_secs)
if n_expected_samples_per_period < 1.0:
raise ValueError('Date period specified by rule is shorter than'
' sample period!')
index = _get_index(data)
index = reframe_index(index, window_start, window_end)
n_samples_per_period = (pd.Series(1, index=index)
.resample(rule=rule, how='sum')
.fillna(0))
dropout_rate_per_period_ = 1 - (n_samples_per_period /
n_expected_samples_per_period)
return dropout_rate_per_period_
def _indicies_of_periods(datetime_index, freq, use_local_time=True):
"""Find which elements of `datetime_index` fall into each period
of a regular periods with frequency `freq`. Uses some tricks to do
this more efficiently that appears possible with native Pandas tools.
Parameters
----------
datetime_index : pd.tseries.index.DatetimeIndex
freq : str
one of the following:
'A' for yearly
'M' for monthly
'D' for daily
'H' for hourly
'T' for minutely
use_local_time : boolean, optional, default=True
If True then start and end each time period at appropriate local times.
e.g. if `freq='D'` and:
`use_local_time=True` then divide at midnight *local time* or if
`use_local_time=False` then divide at midnight UTC
Returns
-------
periods : pd.tseries.period.PeriodIndex
boundaries : dict
Each key is a pd.tseries.period.Period
Each value is a tuple of ints:
(<start index into `datetime_index` for period>, <end index>)
Periods for which no data exists will not have a key.
Examples
--------
Say you have a pd.Series with data covering a month:
>>> series.index
<class 'pandas.tseries.index.DatetimeIndex'>
[2011-04-18 09:22:13, ..., 2011-05-24 15:56:34]
Length: 745878, Freq: None, Timezone: US/Eastern
You want to divide it up into day-sized chunks, starting and ending each
chunk at midnight local time:
>>> periods, boundaries = _indicies_of_periods(series.index, freq='D')
>>> periods
<class 'pandas.tseries.period.PeriodIndex'>
freq: D
[2011-04-18, ..., 2011-05-24]
length: 37
>>> boundaries
{Period('2011-04-18', 'D'): (0, 13652),
Period('2011-04-19', 'D'): (13652, 34926),
Period('2011-04-20', 'D'): (34926, 57310),
...
Period('2011-05-23', 'D'): (710750, 732360),
Period('2011-05-24', 'D'): (732360, 745878)}
Now, say that we want chomp though our data a day at a time:
>>> for period in periods:
>>> start_i, end_i = boundaries[period]
>>> data_for_day = series.iloc[start_i:end_i]
>>> # do something with data_for_day
"""
if use_local_time:
datetime_index = _tz_to_naive(datetime_index)
periods = pd.period_range(datetime_index[0], datetime_index[-1], freq=freq)
# Declare and initialise some constants and variables used
# during the loop...
# Find the minimum sample period.
MIN_SAMPLE_PERIOD = int(get_sample_period(datetime_index))
MAX_SAMPLES_PER_PERIOD = int(
secs_per_period_alias(freq) / MIN_SAMPLE_PERIOD)
MAX_SAMPLES_PER_2_PERIODS = MAX_SAMPLES_PER_PERIOD * 2
n_rows_processed = 0
boundaries = {}
for period in periods:
# The simplest way to get data for just a single period is to use
# data_for_day = datetime_index[period.strftime('%Y-%m-%d')]
# but this takes about 300ms per call on my machine.
# So we take advantage of several features of the data to achieve
# a 300x speedup:
# 1. We use the fact that the data is sorted in order, hence
# we can chomp through it in order.
# 2. MAX_SAMPLES_PER_PERIOD sets an upper bound on the number of
# datapoints per period. The code is conservative and uses
# MAX_SAMPLES_PER_2_PERIODS. We only search through a small subset
# of the available data.
end_index = n_rows_processed + MAX_SAMPLES_PER_2_PERIODS
rows_to_process = datetime_index[n_rows_processed:end_index]
indicies_for_period = np.where(rows_to_process < period.end_time)[0]
if indicies_for_period.size > 0:
first_i_for_period = indicies_for_period[0] + n_rows_processed
last_i_for_period = indicies_for_period[-1] + n_rows_processed + 1
boundaries[period] = (first_i_for_period, last_i_for_period)
n_rows_processed += last_i_for_period - first_i_for_period
return periods, boundaries
def activity_distribution(series, on_power_threshold=DEFAULT_ON_POWER_THRESHOLD,
bin_size='T', timespan='D'):
"""Returns a distribution describing when this appliance was turned
on over repeating timespans. For example, if you want to see
which times of day this appliance was used, on average, then use
bin_size='T' (minutely) or bin_size='H' (hourly) and
timespan='D' (daily).
Parameters
----------
series : pandas.Series
on_power_threshold : float, optional, default=5
Threshold which defines the difference between 'on' and 'off'. Watts.
bin_size, timespan : str
offset alias (e.g. 'T' or 'D')
For valid offset aliases, see:
http://pandas.pydata.org/pandas-docs/dev/timeseries.html#offset-aliases
Returns
-------
pandas.Series
One row for each bin in a timespan.
The values count the number of times this appliance has been on at
that particular time of the timespan.
Times are handled in local time.
The index uses specific dates. For example, if `timespan='D'` then
the index might be from '2012/1/1 00:00' to '2012/1/1 59:59'. In this
example, ignore the '2012/1/1'.
"""
# TODO: replace this evil hack to handle dataframes(!)
if isinstance(series, pd.DataFrame):
series = series.icol(0)
# Create a pd.Series with PeriodIndex
binned_data = series.resample(bin_size, how='max').to_period()
binned_data = binned_data > on_power_threshold
timespans, boundaries = _indicies_of_periods(
binned_data.index.to_timestamp(),
freq=timespan)
first_timespan = timespans[0]
bins = pd.period_range(first_timespan.start_time,
first_timespan.end_time,
freq=bin_size)
distribution = pd.Series(0, index=bins)
bins_per_timespan = int(round(secs_per_period_alias(timespan) /
secs_per_period_alias(bin_size)))
for span in timespans:
try:
start_index, end_index = boundaries[span]
except KeyError:
print("No data for", span)
continue
else:
data_for_timespan = binned_data[start_index:end_index]
bins_since_first_timespan = (first_timespan - span) * bins_per_timespan
data_shifted = data_for_timespan.shift(bins_since_first_timespan,
bin_size)
distribution = distribution.add(data_shifted, fill_value=0)
return distribution
def usage_per_period(series, freq,
on_power_threshold=DEFAULT_ON_POWER_THRESHOLD,
max_dropout_rate=DEFAULT_MAX_DROPOUT_RATE,
verbose=False,
energy_unit='kwh'):
"""Calculate the usage (hours on and kwh) per time period.
If input data has gaps then pre-process data with `insert_zeros`
before sending it to this function.
Parameters
----------
series : pd.Series
freq : str
see _indicies_of_periods() for acceptable values.
on_power_threshold : float or int, optional, default = 5
Threshold which defines the distinction between "on" and "off". Watts.
max_dropout_rate : float (0,1), optional, default = 0.4
Remove any row which has a worse (larger) dropout rate.
verbose : boolean, optional, default = False
if True then print more information
energy_unit : {'kwh', 'joules'}, optional
Returns
-------
usage : pd.DataFrame
One row per period (as defined by `freq`).
Index is PeriodIndex (UTC).
Columns:
hours_on
<`energy_unit`>
Examples
--------
Say we have loaded fridge data from house_1 in REDD into `fridge` and we
want to see how it was used each day:
>>> usage_per_period(fridge, 'D')
hours_on kwh
2011-04-18 NaN NaN
2011-04-19 23.999444 1.104083
2011-04-20 23.998889 1.293223
2011-04-21 23.998889 1.138540
...
2011-05-22 23.832500 2.042271
2011-05-23 23.931111 1.394619
2011-05-24 NaN NaN
Hmmm... why does the fridge appear to be on for 24 hours per day?
Inspecting the fridge.plot(), we find that the fridge rarely ever
gets below this function's default on_power_threshold of 5 Watts,
so let's specify a larger threshold:
>>> usage_per_period(fridge, 'D', on_power_threshold=100)
hours_on kwh
2011-04-18 NaN NaN
2011-04-19 5.036111 1.104083
2011-04-20 5.756667 1.293223
2011-04-21 4.931667 1.138540
2011-04-22 4.926111 1.076958
2011-04-23 6.099167 1.357812
2011-04-24 6.373056 1.361579
2011-04-25 6.496667 1.441966
2011-04-26 6.381389 1.404637
2011-04-27 5.558611 1.196464
2011-04-28 6.668611 1.478141
2011-04-29 6.493056 1.446713
2011-04-30 5.885278 1.263918
2011-05-01 5.983611 1.351419
2011-05-02 5.398333 1.167111
2011-05-03 NaN NaN
2011-05-04 NaN NaN
2011-05-05 NaN NaN
2011-05-06 NaN NaN
2011-05-07 5.112222 1.120848
2011-05-08 6.349722 1.413897
2011-05-09 7.270833 1.573199
2011-05-10 5.997778 1.249120
2011-05-11 5.685556 1.264841
2011-05-12 7.153333 1.478244
2011-05-13 5.949444 1.306350
2011-05-14 6.446944 1.415302
2011-05-15 5.958333 1.275853
2011-05-16 6.801944 1.501816
2011-05-17 5.836389 1.342787
2011-05-18 5.254444 1.164683
2011-05-19 6.234444 1.397851
2011-05-20 5.814444 1.265143
2011-05-21 6.738333 1.498687
2011-05-22 9.308056 2.042271
2011-05-23 6.127778 1.394619
2011-05-24 NaN NaN
That looks sensible! Now, let's find out why the cause of the NaNs by
setting verbose=True:
>>> usage_per_period(fridge, 'D', on_power_threshold=100, verbose=True)
Insufficient samples for 2011-04-18; n samples = 13652; dropout_rate = 52.60%
start = 2011-04-18 09:22:13-04:00
end = 2011-04-18 23:59:57-04:00
Insufficient samples for 2011-05-03; n samples = 16502; dropout_rate = 42.70%
start = 2011-05-03 00:00:03-04:00
end = 2011-05-03 17:33:17-04:00
No data available for 2011-05-04
No data available for 2011-05-05
Insufficient samples for 2011-05-06; n samples = 12465; dropout_rate = 56.72%
start = 2011-05-06 10:51:50-04:00
end = 2011-05-06 23:59:58-04:00
Insufficient samples for 2011-05-24; n samples = 13518; dropout_rate = 53.06%
start = 2011-05-24 00:00:02-04:00
end = 2011-05-24 15:56:34-04:00
Out[209]:
hours_on kwh
2011-04-18 NaN NaN
2011-04-19 5.036111 1.104083
2011-04-20 5.756667 1.293223
...
Ah, OK, there are insufficient samples for the periods with NaNs. We could
set max_dropout_rate to a number closer to 1, but that would give us data
for days where there isn't much data for that day.
"""
# TODO: replace this evil hack to handle dataframes(!)
if isinstance(series, pd.DataFrame):
series = series.icol(0)
assert(0 <= max_dropout_rate <= 1)
period_range, boundaries = _indicies_of_periods(series.index, freq)
name = str(series.name)
hours_on_series = pd.Series(index=period_range, dtype=np.float,
name=name + ' hours on')
energy_series = pd.Series(index=period_range, dtype=np.float,
name=name + ' ' + energy_unit)
MAX_SAMPLES_PER_PERIOD = (secs_per_period_alias(freq) /
get_sample_period(series))
MIN_SAMPLES_PER_PERIOD = (MAX_SAMPLES_PER_PERIOD *
(1 - max_dropout_rate))
for period in period_range:
try:
period_start_i, period_end_i = boundaries[period]
except KeyError:
if verbose:
print("No data available for ",
period.strftime('%Y-%m-%d'))
continue
data_for_period = series[period_start_i:period_end_i]
if data_for_period.size < MIN_SAMPLES_PER_PERIOD:
if verbose:
dropout_rate = (1 - (data_for_period.size /
MAX_SAMPLES_PER_PERIOD))
print("Insufficient samples for ",
period.strftime('%Y-%m-%d'),
"; n samples = ", data_for_period.size,
"; dropout_rate = {:.2%}".format(dropout_rate), sep='')
print(" start =", data_for_period.index[0])
print(" end =", data_for_period.index[-1])
continue
hours_on_series[period] = hours_on(data_for_period,
on_power_threshold=on_power_threshold)
energy_series[period] = energy(data_for_period, unit=energy_unit)
return pd.DataFrame({'hours_on': hours_on_series,
energy_unit: energy_series})
