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[sensor] Fix delta filter percentage mode regression#14302

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swoboda1337 merged 1 commit intoesphome:devfrom
swoboda1337:fix-delta-percentage
Feb 26, 2026
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[sensor] Fix delta filter percentage mode regression#14302
swoboda1337 merged 1 commit intoesphome:devfrom
swoboda1337:fix-delta-percentage

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@swoboda1337 swoboda1337 commented Feb 25, 2026 •
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What does this implement/fix?

Fixes a regression introduced in #12605 where the _get_delta() helper does not divide percentage values by 100 when converting to the linear coefficient used by DeltaFilter.

The old code used cv.percentage() which correctly converts "5%" → 0.05. The new code replaced this with manual string parsing (float(value[:-1])) but forgot the division, so "5%" → 5.0. This means delta: 5% actually requires a 500% change instead of 5%, effectively filtering out all values after the first one.

The fix: divide by 100 in _get_delta():

# Before (broken):
return 0.0, float(value[:-1])        # "5%" → 5.0 (500%)

# After (fixed):
return 0.0, float(value[:-1]) / 100.0  # "5%" → 0.05 (5%)

An integration test for percentage mode is added to catch this regression.

Types of changes

  • Bugfix (non-breaking change which fixes an issue)
  • New feature (non-breaking change which adds functionality)
  • Breaking change (fix or feature that would cause existing functionality to not work as expected)
  • Developer breaking change (an API change that could break external components)
  • Code quality improvements to existing code or addition of tests
  • Other

Related issue or feature (if applicable):

Pull request in esphome-docs with documentation (if applicable):

  • N/A

Test Environment

  • ESP32
  • ESP32 IDF
  • ESP8266
  • RP2040
  • BK72xx
  • RTL87xx
  • LN882x
  • nRF52840

Example entry for config.yaml:

sensor:
  - platform: adc
    pin: GPIO36
    name: "ADC Voltage"
    filters:
      - delta: 5%

Checklist:

  • The code change is tested and works locally.
  • Tests have been added to verify that the new code works (under tests/ folder).

If user exposed functionality or configuration variables are added/changed:

@swoboda1337
[sensor] Fix delta filter percentage values not divided by 100
b3a8ab4 
The _get_delta() helper introduced in esphome#12605 converts percentage strings
like "5%" to float but doesn't divide by 100. This means delta: 5%
actually requires a 500% change instead of 5%, effectively filtering
out all values after the first one.

Fixes esphome#14301

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
@swoboda1337 swoboda1337 requested a review from a team as a code owner February 25, 2026 23:21
Copilot AI review requested due to automatic review settings February 25, 2026 23:21
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github-actions bot commented Feb 25, 2026

👋 Hi there! This PR modifies 1 file(s) with codeowners.

@esphome/core - As codeowner(s) of the affected files, your review would be appreciated! 🙏

Note: Automatic review request may have failed, but you're still welcome to review.

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github-actions bot commented Feb 25, 2026

To use the changes from this PR as an external component, add the following to your ESPHome configuration YAML file:

external_components:
  - source: github://pr#14302
    components: [sensor]
    refresh: 1h

(Added by the PR bot)

@swoboda1337 swoboda1337 added this to the 2026.2.2 milestone Feb 25, 2026
Copilot AI reviewed Feb 25, 2026
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Pull request overview

This PR fixes a critical regression introduced in PR #12605 where percentage-based delta filters (e.g., delta: 5%) were incorrectly converted to their linear coefficients. The bug caused the filter to require a 500% change instead of 5%, effectively filtering out all values after the first one. The fix adds the missing division by 100 when converting percentage strings to decimal coefficients.

Changes:

  • Fixed _get_delta() helper in esphome/components/sensor/__init__.py to divide percentage values by 100
  • Added integration test for percentage mode delta filter to prevent future regressions

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File Description
esphome/components/sensor/init.py Fixed percentage conversion in _get_delta() by adding division by 100
tests/integration/test_sensor_filters_delta.py Added Test 5 for percentage mode delta filter with proper assertions
tests/integration/fixtures/sensor_filters_delta.yaml Added source sensor 5, filter_percentage sensor, test script, and button for percentage mode testing

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codecov-commenter commented Feb 25, 2026 •
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Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 74.25%. Comparing base (534857d) to head (b3a8ab4).

Additional details and impacted files 
@@            Coverage Diff             @@
##              dev   #14302      +/-   ##
==========================================
- Coverage   74.28%   74.25%   -0.03%     
==========================================
  Files          55       55              
  Lines       11595    11595              
  Branches     1583     1583              
==========================================
- Hits         8613     8610       -3     
- Misses       2578     2580       +2     
- Partials      404      405       +1

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:
  • ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

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github-actions bot commented Feb 26, 2026

Memory Impact Analysis

Components: sensor
Platform: esp8266-ard

Metric Target Branch This PR Change
RAM 29,344 bytes 29,344 bytes ➡️ +0 bytes (0.00%)
Flash 289,323 bytes 289,323 bytes ➡️ +0 bytes (0.00%)

Note: This analysis measures static RAM and Flash usage only (compile-time allocation).
Dynamic memory (heap) cannot be measured automatically.
⚠️ You must test this PR on a real device to measure free heap and ensure no runtime memory issues.

This analysis runs automatically when components change. Memory usage is measured from a representative test configuration.

@swoboda1337 swoboda1337 merged commit 0d5b7df into esphome:dev Feb 26, 2026
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swoboda1337 commented Feb 26, 2026

Thanks

jesserockz pushed a commit that referenced this pull request Feb 26, 2026
@swoboda1337 @jesserockz
[sensor] Fix delta filter percentage mode regression (#14302)
8479664 
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
@jesserockz jesserockz mentioned this pull request Feb 26, 2026
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@neilmartin83 neilmartin83 mentioned this pull request Feb 26, 2026
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@bdraco bdraco bdraco approved these changes

@clydebarrow clydebarrow Awaiting requested review from clydebarrow

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bugfix cherry-picked component: sensor has-tests

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2026.2.2

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Successfully merging this pull request may close these issues.

"Delta" sensor filter stopped working starting from ESPHome 2026.2.0

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