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make volume tracker robust against floating point inaccuracies #733

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Merged
merged 3 commits into from
Nov 10, 2025
Merged

make volume tracker robust against floating point inaccuracies #733

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dc6d81e
vols
fderop Oct 25, 2025
154ec72
add
fderop Oct 25, 2025
962ab55
fix it
rickwierenga Nov 10, 2025
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8 changes: 4 additions & 4 deletions pylabrobot/resources/volume_tracker.py
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Original file line number Diff line number Diff line change
Expand Up @@ -124,7 +124,7 @@ def remove_liquid(self, volume: float) -> List[Tuple[Optional["Liquid"], float]]
"""Remove liquid from the container. Top to bottom."""

available_volume = self.get_used_volume()
if volume > available_volume and abs(volume - available_volume) > 1e-6:
if (volume - available_volume) > 1e-6:
raise TooLittleLiquidError(
f"Container {self.thing} has too little liquid: {volume}uL > {available_volume}uL."
)
Expand All @@ -136,7 +136,7 @@ def remove_liquid(self, volume: float) -> List[Tuple[Optional["Liquid"], float]]
removed_volume += liquid_volume

# If we have more liquid than we need, put the excess back.
if removed_volume > volume and abs(removed_volume - volume) > 1e-6:
if removed_volume > volume:
self.pending_liquids.append((liquid, removed_volume - volume))
removed_liquids.append((liquid, liquid_volume - (removed_volume - volume)))
else:
Expand All @@ -150,7 +150,7 @@ def remove_liquid(self, volume: float) -> List[Tuple[Optional["Liquid"], float]]
def add_liquid(self, liquid: Optional["Liquid"], volume: float) -> None:
"""Add liquid to the container."""

if volume > self.get_free_volume():
if (volume - self.get_free_volume()) > 1e-6:
raise TooLittleVolumeError(
f"Container {self.thing} has too little volume: {volume}uL > {self.get_free_volume()}uL."
)
Expand Down Expand Up @@ -188,7 +188,7 @@ def get_free_volume(self) -> float:
def get_liquids(self, top_volume: float) -> List[Tuple[Optional[Liquid], float]]:
"""Get the liquids in the top `top_volume` uL"""

if top_volume > self.get_used_volume():
if (top_volume - self.get_used_volume()) > 1e-6:
raise TooLittleLiquidError(f"Tracker only has {self.get_used_volume()}uL")

liquids = []
Expand Down