DOC: Add example for Polynomial.degree(). (#23530)

Include additional example about 0-coefficients and the trim method.

Co-authored-by: Ross Barnowski <rossbar@berkeley.edu>

1 files changed, 22 insertions, 0 deletions

diff --git a/numpy/polynomial/_polybase.py b/numpy/polynomial/_polybase.py
index a5c7c6415..9730574cf 100644
--- a/numpy/polynomial/_polybase.py
+++ b/numpy/polynomial/_polybase.py
@@ -682,6 +682,28 @@ class ABCPolyBase(abc.ABC):
         degree : int
             Degree of the series, one less than the number of coefficients.
 
+        Examples
+        --------
+
+        Create a polynomial object for ``1 + 7*x + 4*x**2``:
+
+        >>> poly = np.polynomial.Polynomial([1, 7, 4])
+        >>> print(poly)
+        1.0 + 7.0·x + 4.0·x²
+        >>> poly.degree()
+        2
+
+        Note that this method does not check for non-zero coefficients.
+        You must trim the polynomial to remove any trailing zeroes:
+
+        >>> poly = np.polynomial.Polynomial([1, 7, 0])
+        >>> print(poly)
+        1.0 + 7.0·x + 0.0·x²
+        >>> poly.degree()
+        2
+        >>> poly.trim().degree()
+        1
+
         """
         return len(self) - 1