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weewx/bin/weeplot/utilities.py
Tom Keffer 16c0d225f4 Use attribute self.stn_info for lat/lon information. 
Changed function parameter ordering to lat/lon.
Added doctests for function tobool(). Moved it to weeutil.weeutil
Presently crashes if sunset is after midnight UTC.
2013-01-18 19:27:04 +00:00

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#
# Copyright (c) 2009 Tom Keffer <tkeffer@gmail.com>
#
# See the file LICENSE.txt for your full rights.
#
# $Revision$
# $Author$
# $Date$
#
"""Various utilities used by the plot package.
"""
import ImageFont
import ImageColor
import datetime
import time
import math
import weeplot
def scale(fmn, fmx, prescale = (None, None, None), nsteps = 10):
"""Calculates an appropriate min, max, and step size for scaling axes on a plot.
The origin (zero) is guaranteed to be on an interval boundary.
fmn: The minimum data value
fmx: The maximum data value. Must be greater than or equal to fmn.
prescale: A 3-way tuple. A non-None min or max value (positions 0 and 1,
respectively) will be fixed to that value. A non-None interval (position 2)
be at least as big as that value. Default = (None, None, None)
nsteps: The nominal number of desired steps. Default = 10
Returns: a three-way tuple. First value is the lowest scale value, second the highest.
The third value is the step (increment) between them.
Examples:
>>> print scale(1.1, 12.3)
(0.0, 14.0, 2.0)
>>> print scale(-1.1, 12.3)
(-2.0, 14.0, 2.0)
>>> print scale(-12.1, -5.3)
(-13.0, -5.0, 1.0)
>>> print scale(10.0, 10.0)
(10.0, 10.1, 0.01)
>>> print "(%.4f, %.4f, %.5f)" % scale(10.0, 10.001)
(10.0000, 10.0010, 0.00010)
>>> print scale(10.0, 10.0+1e-8)
(10.0, 10.1, 0.01)
>>> print scale(0.0, 0.05, (None, None, .1), 10)
(0.0, 1.0, 0.1)
>>> print scale(0.0, 0.21, (None, None, .02))
(0.0, 0.22, 0.02)
"""
if all(x is not None for x in prescale):
return prescale
(minscale, maxscale, min_interval) = prescale
# Make sure fmn and fmx are float values, in case a user passed
# in integers:
fmn = float(fmn)
fmx = float(fmx)
if fmx < fmn :
raise weeplot.ViolatedPrecondition, "scale() called with max value less than min value"
if _rel_approx_equal(fmn, fmx) :
if fmn == 0.0 :
fmx = 1.0
else :
fmx = fmn + .01*abs(fmn)
frange = fmx - fmn
steps = frange / nsteps
mag = math.floor(math.log10(steps))
magPow = math.pow(10.0, mag)
magMsd = math.floor(steps/magPow + 0.5)
if magMsd > 5.0:
magMsd = 10.0
elif magMsd > 2.0:
magMsd = 5.0
else : # magMsd > 1.0
magMsd = 2
# This will be the nominal interval size
interval = magMsd * magPow
# Test it against the desired minimum, if any
if min_interval is None or interval >= min_interval:
# Either no min interval was specified, or its safely
# less than the chosen interval.
if minscale is None:
minscale = interval * math.floor(fmn / interval)
if maxscale is None:
maxscale = interval * math.ceil(fmx / interval)
else:
# The request for a minimum interval has kicked in.
# Sometimes this can make for a plot with just one or
# two intervals in it. Adjust the min and max values
# to get a nice plot
interval = min_interval
if minscale is None:
if maxscale is None:
# Both can float. Pick values so the range is near the bottom
# of the scale:
minscale = interval * math.floor(fmn / interval)
maxscale = minscale + interval * nsteps
else:
# Only minscale can float
minscale = maxscale - interval * nsteps
else:
if maxscale is None:
# Only maxscale can float
maxscale = minscale + interval * nsteps
else:
# Both are fixed --- nothing to be done
pass
return (minscale, maxscale, interval)
def scaletime(tmin_ts, tmax_ts) :
"""Picks a time scaling suitable for a time plot.
tmin_ts, tmax_ts: The time stamps in epoch time around which the times will be picked.
Returns a scaling 3-tuple. First element is the start time, second the stop
time, third the increment. All are in seconds (epoch time in the case of the
first two). """
if tmax_ts <= tmin_ts :
raise weeplot.ViolatedPrecondition, "scaletime called with tmax <= tmin"
tdelta = tmax_ts - tmin_ts
tmin_dt = datetime.datetime.fromtimestamp(tmin_ts)
tmax_dt = datetime.datetime.fromtimestamp(tmax_ts)
# How big a time delta are we talking about?
if tdelta <= 27 * 3600 :
# A day plot is wanted. A time increment of 3 hours is appropriate
# h is the hour of tmin_dt
h = tmin_dt.timetuple()[3]
# Subtract off enough to get to the lower 3-hour boundary,
# zeroing out everything else
start_dt = tmin_dt.replace(minute=0, second=0, microsecond=0) - datetime.timedelta(hours = h % 3)
# Now figure the upper time boundary, which is a bit more complicated if tmax_dt lies
# near the 3-hour boundary
tmax_tt = tmax_dt.timetuple()
# stop_dt is the lower 3-hour boundary from tmax_dt
stop_dt = tmax_dt.replace(minute=0, second=0, microsecond=0)
# If the tmax_dt was close to the 3-hour boundary, we're done. Otherwise, go up to
# the next 3-hour boundary.
if tmax_tt[3] % 3 != 0 or tmax_tt[4] != 0 :
stop_dt += datetime.timedelta(hours = 3 - tmax_tt[3] % 3)
interval = 3 * 3600
elif tdelta > 27 * 3600 and tdelta <= 31 * 24 * 3600 :
# The time scale is between a day and a month. A time increment of one day is appropriate
start_dt = tmin_dt.replace(hour=0, minute=0, second=0, microsecond=0)
stop_dt = tmax_dt.replace(hour=0, minute=0, second=0, microsecond=0)
tmax_tt = tmax_dt.timetuple()
if tmax_tt[3]!=0 or tmax_tt[4]!=0 :
stop_dt += datetime.timedelta(days=1)
interval = 24 * 3600
else :
# The time scale is more than a month. A time increment of a month is appropriate
start_dt = tmin_dt.replace(day=1, hour=0, minute=0, second=0, microsecond=0)
(year , mon, day) = tmax_dt.timetuple()[0:3]
if day != 1 :
mon += 1
if mon==13 :
mon = 1
year += 1
stop_dt = datetime.datetime(year, mon, 1)
# Average month length:
interval = 365.25/12 * 24 * 3600
# Convert to epoch time stamps
start_ts = int(time.mktime(start_dt.timetuple()))
stop_ts = int(time.mktime(stop_dt.timetuple()))
return (start_ts, stop_ts, interval)
class ScaledDraw(object):
"""Like an ImageDraw object, but lines are scaled.
"""
def __init__(self, draw, imagebox, scaledbox):
"""Initialize a ScaledDraw object.
Example:
scaledraw = ScaledDraw(draw, ((10, 10), (118, 246)), ((0.0, 0.0), (10.0, 1.0)))
would create a scaled drawing where the upper-left image coordinate (10, 10) would
correspond to the scaled coordinate( 0.0, 1.0). The lower-left image coordinate
would correspond to the scaled coordinate (10.0, 0.0).
draw: an instance of ImageDraw
imagebox: a 2-tuple of the box coordinates on the image ((ulx, uly), (lrx, lry))
scaledbox: a 2-tuple of the box coordinates of the scaled plot ((llx, lly), (urx, ury))
"""
uli = imagebox[0]
lri = imagebox[1]
lls = scaledbox[0]
urs = scaledbox[1]
if urs[1] == lls[1]:
pass
self.xscale = float(lri[0] - uli[0]) / float(urs[0] - lls[0])
self.yscale = -float(lri[1] - uli[1]) / float(urs[1] - lls[1])
self.xoffset = int(lri[0] - urs[0] * self.xscale + 0.5)
self.yoffset = int(uli[1] - urs[1] * self.yscale + 0.5)
self.draw = draw
def line(self, x, y, line_type='solid', marker_type=None, marker_size=8, maxdx=None, **options) :
"""Draw a scaled line on the instance's ImageDraw object.
x: sequence of x coordinates
y: sequence of y coordinates, some of which are possibly null (value of None)
line_type: 'solid' for line that connect the coordinates
None for no line
marker_type: None or 'none' for no marker.
'cross' for a cross
'circle' for a circle
'box' for a box
'x' for an X
maxdx: defines what constitutes a gap in samples. if two data points
are more than maxdx apart they are treated as separate segments.
For a scatter plot, set line_type to None and marker_type to something other than None.
"""
# Break the line up around any nulls or gaps between samples
for xy_seq in xy_seq_line(x, y, maxdx):
# Create a list with the scaled coordinates...
xy_seq_scaled = [(self.xtranslate(xc), self.ytranslate(yc)) for (xc,yc) in xy_seq]
if line_type == 'solid':
# Now pick the appropriate drawing function, depending on the length of the line:
if len(xy_seq) == 1 :
self.draw.point(xy_seq_scaled, fill=options['fill'])
else :
self.draw.line(xy_seq_scaled, **options)
if marker_type and marker_type.lower().strip() not in ['none', '']:
self.marker(xy_seq_scaled, marker_type, marker_size=marker_size, **options)
def marker(self, xy_seq, marker_type, marker_size=10, **options):
half_size = marker_size/2
marker=marker_type.lower()
for x, y in xy_seq:
if marker == 'cross':
self.draw.line([(x-half_size, y), (x+half_size, y)], **options)
self.draw.line([(x, y-half_size), (x, y+half_size)], **options)
elif marker == 'x':
self.draw.line([(x-half_size, y-half_size), (x+half_size, y+half_size)], **options)
self.draw.line([(x-half_size, y+half_size), (x+half_size, y-half_size)], **options)
elif marker == 'circle':
self.draw.ellipse([(x-half_size, y-half_size),
(x+half_size, y+half_size)], outline=options['fill'])
elif marker == 'box':
self.draw.line([(x-half_size, y-half_size),
(x+half_size, y-half_size),
(x+half_size, y+half_size),
(x-half_size, y+half_size),
(x-half_size, y-half_size)], **options)
def rectangle(self, box, **options) :
"""Draw a scaled rectangle.
box: A pair of 2-way tuples, containing coordinates of opposing corners
of the box.
options: passed on to draw.rectangle. Usually contains 'fill' (the color)
"""
box_scaled = [(coord[0]*self.xscale + self.xoffset + 0.5, coord[1]*self.yscale + self.yoffset + 0.5) for coord in box]
self.draw.rectangle(box_scaled, **options)
def vector(self, x, vec, vector_rotate, **options):
if vec is None:
return
xstart_scaled = self.xtranslate(x)
ystart_scaled = self.ytranslate(0)
vecinc_scaled = vec * self.yscale
if vector_rotate:
vecinc_scaled *= complex(math.cos(math.radians(vector_rotate)),
math.sin(math.radians(vector_rotate)))
# Subtract off the x increment because the x-axis
# *increases* to the right, unlike y, which increases
# downwards
xend_scaled = xstart_scaled - vecinc_scaled.real
yend_scaled = ystart_scaled + vecinc_scaled.imag
self.draw.line(((xstart_scaled, ystart_scaled), (xend_scaled, yend_scaled)), **options)
def xtranslate(self, x):
return int(x * self.xscale + self.xoffset + 0.5)
def ytranslate(self, y):
return int(y * self.yscale + self.yoffset + 0.5)
def xy_seq_line(x, y, maxdx=None):
"""Generator function that breaks a line up into individual segments around
any nulls held in y or any gaps in x greater than maxdx.
x: iterable sequence of x coordinates. All values must be non-null
y: iterable sequence of y coordinates, possibly with some embedded
nulls (that is, their value==None)
yields: Lists of (x,y) coordinates
Example 1
>>> x=[ 1, 2, 3]
>>> y=[10, 20, 30]
>>> for xy_seq in xy_seq_line(x,y):
... print xy_seq
[(1, 10), (2, 20), (3, 30)]
Example 2
>>> x=[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
>>> y=[0, 10, None, 30, None, None, 60, 70, 80, None]
>>> for xy_seq in xy_seq_line(x,y):
... print xy_seq
[(0, 0), (1, 10)]
[(3, 30)]
[(6, 60), (7, 70), (8, 80)]
Example 3
>>> x=[ 0 ]
>>> y=[None]
>>> for xy_seq in xy_seq_line(x,y):
... print xy_seq
Example 4
>>> x=[ 0, 1, 2]
>>> y=[None, None, None]
>>> for xy_seq in xy_seq_line(x,y):
... print xy_seq
Example 5 (using gap)
>>> x=[0, 1, 2, 3, 5.1, 6, 7, 8, 9]
>>> y=[0, 10, 20, 30, 50, 60, 70, 80, 90]
>>> for xy_seq in xy_seq_line(x,y,2):
... print xy_seq
[(0, 0), (1, 10), (2, 20), (3, 30)]
[(5.1, 50), (6, 60), (7, 70), (8, 80), (9, 90)]
"""
line = []
last_x = None
for xy in zip(x, y):
dx = xy[0] - last_x if last_x is not None else 0
last_x = xy[0]
# If the y coordinate is None or dx > maxdx, that marks a break
if xy[1] is None or (maxdx is not None and dx > maxdx):
# If the length of the line is non-zero, yield it
if len(line):
yield line
line = [] if xy[1] is None else [xy]
else:
line.append(xy)
if len(line):
yield line
def pickLabelFormat(increment):
"""Pick an appropriate label format for the given increment.
Examples:
>>> print pickLabelFormat(1)
%.0f
>>> print pickLabelFormat(20)
%.0f
>>> print pickLabelFormat(.2)
%.1f
>>> print pickLabelFormat(.01)
%.2f
"""
i_log = math.log10(increment)
if i_log < 0 :
i_log = abs(i_log)
decimal_places = int(i_log)
if i_log != decimal_places :
decimal_places += 1
else :
decimal_places = 0
return "%%.%df" % decimal_places
def get_font_handle(fontpath, *args):
font = None
if fontpath is not None :
try :
if fontpath.endswith('.ttf'):
font = ImageFont.truetype(fontpath, *args)
else :
font = ImageFont.load_path(fontpath)
except IOError :
pass
if font is None :
font = ImageFont.load_default()
return font
def _rel_approx_equal(x, y, rel=1e-7):
"""Relative test for equality.
Example
>>> _rel_approx_equal(1.23456, 1.23457)
False
>>> _rel_approx_equal(1.2345678, 1.2345679)
True
>>> _rel_approx_equal(0.0, 0.0)
True
>>> _rel_approx_equal(0.0, 0.1)
False
>>> _rel_approx_equal(0.0, 1e-9)
False
>>> _rel_approx_equal(1.0, 1.0+1e-9)
True
>>> _rel_approx_equal(1e8, 1e8+1e-3)
True
"""
return abs(x-y) <= rel*max(abs(x), abs(y))
def tobgr(x):
"""Convert a color to little-endian integer. The PIL wants either
a little-endian integer (0xBBGGRR) or a string (#RRGGBB). weewx expects
little-endian integer. Accept any standard color format that is known
by ImageColor for example #RGB, #RRGGBB, hslHSL as well as standard color
names from X11 and CSS3. See ImageColor for complete set of colors.
"""
if isinstance(x, basestring):
if x.startswith('0x'):
return int(x, 0)
try:
(r,g,b) = ImageColor.getrgb(x)
return r + g*256 + b*256*256
except :
pass
try:
return int(x)
except ValueError:
pass
raise ValueError("Unknown color specifier: '%s'. Colors must be specified as 0xBBGGRR, #RRGGBB, or standard color names." % x)
return x
if __name__ == "__main__":
import doctest
if not doctest.testmod().failed:
print "PASSED"
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