Initial shitty commit of skew-T chart rendering
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XANTRONIX Industrial
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1 changed files with 194 additions and 0 deletions
194
lib/xmet/skew_t.py
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194
lib/xmet/skew_t.py
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#! /usr/bin/env python3
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import math
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import cairo
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IMAGE_WIDTH = 1366
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IMAGE_HEIGHT = 768
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GRAPH_HEIGHT = IMAGE_HEIGHT - 64
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GRAPH_WIDTH = (GRAPH_HEIGHT / 10.0) * 18
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GRAPH_OFFSET_X = (IMAGE_WIDTH - GRAPH_WIDTH) / 2
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GRAPH_OFFSET_Y = 32
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PRESSURE_MAX = 1050
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PRESSURE_MIN = 100
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PRESSURE_STEP = 50
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PRESSURE_LOG_MAX = math.log(PRESSURE_MAX)
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PRESSURE_LOG_MIN = math.log(PRESSURE_MIN)
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PRESSURE_LOG_RANGE = PRESSURE_LOG_MAX - PRESSURE_LOG_MIN
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TEMP_CENTER = 0 # degrees C
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TEMP_STEP = 5
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TEMP_STEP_WIDTH = GRAPH_HEIGHT / 10.0
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ADIABATIC_LAPSE_RATE_DRY = 9.8 / 1000 # degrees C per 1000m
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ADIABATIC_LAPSE_RATE_MOIST = 4.0 / 1000
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def clamp(value, lowest, highest):
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if value < lowest:
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return lowest
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elif value > highest:
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return highest
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return value
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def pressure_y(pressure: float) -> float:
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if pressure < PRESSURE_MIN:
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pressure = PRESSURE_MIN
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elif pressure > PRESSURE_MAX:
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pressure = PRESSURE_MAX
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log_p = math.log(pressure)
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factor = (PRESSURE_LOG_MAX - log_p) / PRESSURE_LOG_RANGE
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return factor * GRAPH_HEIGHT
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def graph_to_screen(x, y) -> tuple:
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return (
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GRAPH_OFFSET_X + x,
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IMAGE_HEIGHT - GRAPH_OFFSET_Y - y
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)
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def draw_pressure_lines(cr: cairo.Context):
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for pressure in range(PRESSURE_MIN, PRESSURE_MAX+1, PRESSURE_STEP):
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(x, y) = graph_to_screen(0, pressure_y(pressure))
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cr.set_source_rgba(0.0, 0.0, 0.0, 0.5)
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cr.move_to(x, y)
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cr.rel_line_to(GRAPH_WIDTH, 0)
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cr.stroke()
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def draw_graph_line(cr: cairo.Context, x1, y1, x2, y2):
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(screen_x1, screen_y1) = graph_to_screen(x1, y1)
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(screen_x2, screen_y2) = graph_to_screen(x2, y2)
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cr.move_to(screen_x1, screen_y1)
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cr.line_to(screen_x2, screen_y2)
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cr.stroke()
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ISOTHERM_LINES = (
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(0, 0, 9, 9), (1, 0, 9, 8), (2, 0, 9, 7), (3, 0, 9, 6),
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(4, 0, 9, 5), (5, 0, 9, 4), (6, 0, 9, 3), (7, 0, 9, 2),
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(8, 0, 9, 1), (9, 0, 9, 0),
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(-1, 0, 9, 10), (-2, 0, 8, 10), (-3, 0, 7, 10), (-4, 0, 6, 10),
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(-5, 0, 5, 10), (-6, 0, 4, 10), (-7, 0, 3, 10), (-8, 0, 2, 10),
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(-9, 0, 1, 10),
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(-9, 1, 0, 10), (-9, 2, -1, 10), (-9, 3, -2, 10),
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(-9, 4, -3, 10), (-9, 5, -4, 10), (-9, 6, -5, 10),
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(-9, 7, -6, 10), (-9, 8, -7, 10), (-9, 9, -8, 10),
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)
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def isotherm_to_graph(x, y) -> tuple:
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return (
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GRAPH_WIDTH / 2 + x,
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y
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)
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def draw_isotherms(cr: cairo.Context):
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cr.set_source_rgba(0.1, 0.5, 0.1, 0.8)
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for line in ISOTHERM_LINES:
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x1 = line[0] * TEMP_STEP_WIDTH
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y1 = line[1] * TEMP_STEP_WIDTH
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x2 = line[2] * TEMP_STEP_WIDTH
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y2 = line[3] * TEMP_STEP_WIDTH
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graph_1 = isotherm_to_graph(x1, y1)
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graph_2 = isotherm_to_graph(x2, y2)
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draw_graph_line(cr, graph_1[0], graph_1[1], graph_2[0], graph_2[1])
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def sample_to_graph(temp: float, pressure: float):
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x = (temp / TEMP_STEP) * TEMP_STEP_WIDTH
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y = pressure_y(pressure)
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return (
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GRAPH_WIDTH / 2 + x + y,
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y
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)
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SAMPLES = (
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( 101200, -6),
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( 101200, -6),
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( 100000, -12),
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( 99300, -22),
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( 98700, -29),
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( 97500, -39),
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( 95700, -50),
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( 95100, -47),
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( 93900, -43),
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( 92000, -34),
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( 90400, -34),
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( 90000, -34),
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( 89200, -34),
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( 85000, -34),
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( 83700, -34),
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( 82100, -34),
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( 80000, -42),
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( 78600, -46),
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( 77600, -50),
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( 70000, -77),
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( 69100, -80),
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( 60700, -128),
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( 60000, -133),
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( 53100, -186),
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( 50000, -215),
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( 46300, -255),
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( 40200, -337),
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( 40000, -340),
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( 35000, -412),
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( 34900, -413),
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( 30100, -496),
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( 30000, -496),
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( 25700, -565),
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( 25000, -577),
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( 24400, -585),
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( 22100, -510),
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( 21900, -510),
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( 20000, -497),
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( 15000, -466),
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( 10000, -438),
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( 7000, -414),
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( 5000, -393),
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( 3000, -368),
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( 2000, -344),
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( 1500, -337),
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( 1000, -305),
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( 500, -210),
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( 400, -198)
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)
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with cairo.SVGSurface('test.svg', IMAGE_WIDTH, IMAGE_HEIGHT) as surface:
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cr = cairo.Context(surface)
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cr.rectangle(GRAPH_OFFSET_X, GRAPH_OFFSET_Y, GRAPH_WIDTH, GRAPH_HEIGHT)
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cr.stroke()
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draw_pressure_lines(cr)
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draw_isotherms(cr)
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cr.set_source_rgb(0, 0, 1)
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first = True
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for sample in SAMPLES:
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pressure = sample[0] / 100.0
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temp = sample[1] * 0.1
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gx, gy = sample_to_graph(temp, pressure)
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x, y = graph_to_screen(gx, gy)
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print(f"x {x} y {y} pressure {pressure} temp {temp}")
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if first:
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cr.move_to(x, y)
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first = False
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else:
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cr.line_to(x, y)
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cr.stroke()
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