From 099114cd743b4460a46e73c5dcb84e3f02e84f82 Mon Sep 17 00:00:00 2001
From: Gaurav Kumar Biswas <2025sl93041@wilp.bits-pilani.ac.in>
Date: Mon, 9 Nov 2026 22:43:28 +0530
Subject: [PATCH] fix: support fractional values in dehumanize()
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`dehumanize()` used `re.compile(r"\d+")` to extract numbers from the
input string. This pattern only matches whole integers, so a decimal
like "1.5" was never matched as a unit — each digit ran independently,
producing a wildly wrong result (e.g. "1.5 hours ago" shifted by -5 h
instead of -1.5 h).

Fix: change the number regex to `r"\d+(?:\.\d+)?"` everywhere it is
used (the standalone `num_pattern` and the per-timeframe format call),
and switch storage and parsing to `float` so that fractional values
propagate correctly to `shift()`.

Closes #1341
---
 arrow/arrow.py      | 12 ++++++------
 tests/test_arrow.py |  7 +++++++
 2 files changed, 13 insertions(+), 6 deletions(-)

diff --git a/arrow/arrow.py b/arrow/arrow.py
index eecf23266..abb390756 100644
--- a/arrow/arrow.py
+++ b/arrow/arrow.py
@@ -1382,7 +1382,7 @@ def dehumanize(self, input_string: str, locale: str = "en_us") -> "Arrow":
 
         # Create an object containing the relative time info
         time_object_info = dict.fromkeys(
-            ["seconds", "minutes", "hours", "days", "weeks", "months", "years"], 0
+            ["seconds", "minutes", "hours", "days", "weeks", "months", "years"], 0.0
         )
 
         # Create an object representing if unit has been seen
@@ -1391,8 +1391,8 @@ def dehumanize(self, input_string: str, locale: str = "en_us") -> "Arrow":
             False,
         )
 
-        # Create a regex pattern object for numbers
-        num_pattern = re.compile(r"\d+")
+        # Create a regex pattern object for numbers (integers and decimals like "1.5")
+        num_pattern = re.compile(r"\d+(?:\.\d+)?")
 
         # Search input string for each time unit within locale
         for unit, unit_object in locale_obj.timeframes.items():
@@ -1408,7 +1408,7 @@ def dehumanize(self, input_string: str, locale: str = "en_us") -> "Arrow":
             for time_delta, time_string in strings_to_search.items():
                 # Replace {0} with regex \d representing digits
                 search_string = str(time_string)
-                search_string = search_string.format(r"\d+")
+                search_string = search_string.format(r"\d+(?:\.\d+)?")
 
                 # Create search pattern and find within string
                 pattern = re.compile(rf"(^|\b|\d){search_string}")
@@ -1425,10 +1425,10 @@ def dehumanize(self, input_string: str, locale: str = "en_us") -> "Arrow":
                 # Need for absolute value as some locales have signs included in their objects
                 if not num_match:
                     change_value = (
-                        1 if not time_delta.isnumeric() else abs(int(time_delta))
+                        1.0 if not time_delta.isnumeric() else abs(float(time_delta))
                     )
                 else:
-                    change_value = int(num_match.group())
+                    change_value = float(num_match.group())
 
                 # No time to update if now is the unit
                 if unit == "now":
diff --git a/tests/test_arrow.py b/tests/test_arrow.py
index b595e4e21..fa9faa953 100644
--- a/tests/test_arrow.py
+++ b/tests/test_arrow.py
@@ -2987,6 +2987,13 @@ def test_czech_slovak(self):
                 assert arw.dehumanize(past_string, locale=lang) == past
                 assert arw.dehumanize(future_string, locale=lang) == future
 
+    def test_fractional_units(self):
+        arw = arrow.Arrow(2026, 1, 1, tzinfo="UTC")
+        assert arw.dehumanize("1.5 hours ago") == arw.shift(hours=-1.5)
+        assert arw.dehumanize("0.5 days ago") == arw.shift(days=-0.5)
+        assert arw.dehumanize("in 1.5 hours") == arw.shift(hours=1.5)
+        assert arw.dehumanize("2.5 weeks ago") == arw.shift(weeks=-2.5)
+
 
 class TestArrowIsBetween:
     def test_start_before_end(self):