fix: variances was missing sqrt (#150)

scikit-hep · Mar 16, 2021 · 62fdc1f · 62fdc1f
1 parent 4e1c461
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diff --git a/docs/changelog.rst b/docs/changelog.rst
@@ -4,6 +4,9 @@ Changelog
 Version 2.2.1
 --------------------
 
+* Fix bug with `plot_pull` missing a sqrt.
+  `#150 <https://github.com/scikit-hep/hist/pull/150>`_
+
 * Fix static typing with ellipses.
   `#145 <https://github.com/scikit-hep/hist/pull/145>`_
 

diff --git a/src/hist/plot.py b/src/hist/plot.py
@@ -170,7 +170,12 @@ def plot_pull(
 
     # Computation and Fit
     values = self.values()
-    yerr = self.variances()
+    variances = self.variances()
+    if variances is None:
+        raise RuntimeError(
+            "Cannot compute from a variance-less histogram, try a Weight storage"
+        )
+    yerr = np.sqrt(variances)
 
     # Compute fit values: using func as fit model
     popt, pcov = curve_fit(f=func, xdata=self.axes[0].centers, ydata=values)