Repository: PlasmaPy/PlasmaPy

Issue:
Remove deprecated `T_i` argument from `gyroradius`
In #1170, we deprecated the `T_i` argument to `plasmapy.formulary.lengths.gyroradius`.  We've had a few releases since then, so it's probably safe to remove this, update the docstring and tests, and add a `breaking` changelog entry.  


Discussion:
Hello, I would like to work on this as my first contribution. 
@tranqver — That would be great!  Please feel free to do so!

Resolving patch:
diff --git a/plasmapy/formulary/lengths.py b/plasmapy/formulary/lengths.py
--- a/plasmapy/formulary/lengths.py
+++ b/plasmapy/formulary/lengths.py
@@ -92,11 +92,6 @@ def Debye_length(T_e: u.K, n_e: u.m**-3) -> u.m:
 
 @validate_quantities(
     Vperp={"can_be_nan": True},
-    T_i={
-        "can_be_nan": True,
-        "equivalencies": u.temperature_energy(),
-        "none_shall_pass": True,
-    },
     T={
         "can_be_nan": True,
         "equivalencies": u.temperature_energy(),
@@ -110,7 +105,6 @@ def gyroradius(
     particle: ParticleLike,
     *,
     Vperp: u.m / u.s = np.nan * u.m / u.s,
-    T_i: u.K = None,
     T: u.K = None,
     lorentzfactor=np.nan,
     relativistic: bool = True,
@@ -137,10 +131,6 @@ def gyroradius(
     T : `~astropy.units.Quantity`, optional, |keyword-only|
         The particle temperature in units convertible to kelvin.
 
-    T_i : `~astropy.units.Quantity`, optional, |keyword-only|
-        The particle temperature in units convertible to kelvin.
-        Note: Deprecated. Use ``T`` instead.
-
     lorentzfactor : `float` or `~numpy.ndarray`, optional, |keyword-only|
         The Lorentz factor for the particles, use for high precision.
 
@@ -226,20 +216,6 @@ def gyroradius(
     <Quantity 0.001421... m>
     """
 
-    # Backwards Compatibility and Deprecation check for keyword T_i
-    if T_i is not None:
-        warnings.warn(
-            "Keyword T_i is deprecated, use T instead.",
-            PlasmaPyFutureWarning,
-        )
-        if T is None:
-            T = T_i
-        else:
-            raise ValueError(
-                "Keywords T_i and T are both given.  T_i is deprecated, "
-                "please use T only."
-            )
-
     if not relativistic:
         if not np.isnan(lorentzfactor):
             raise ValueError(


Test patch:
diff --git a/plasmapy/formulary/tests/test_lengths.py b/plasmapy/formulary/tests/test_lengths.py
--- a/plasmapy/formulary/tests/test_lengths.py
+++ b/plasmapy/formulary/tests/test_lengths.py
@@ -111,7 +111,6 @@ class TestGyroradius:
             ((B_arr, "e-"), {"Vperp": V_arr, "T": T_i}, ValueError),
             ((B_arr, "e-"), {"Vperp": V, "T": T_nanarr}, ValueError),
             ((B_arr, "e-"), {"Vperp": V_nanarr, "T": T_i}, ValueError),
-            ((0.4 * u.T, "e-"), {"T": 5 * u.eV, "T_i": 7 * u.eV}, ValueError),
             ((B_arr, "e-"), {"lorentzfactor": [3.0, 2.0]}, ValueError),
             (
                 (B_arr, "e-"),
@@ -309,14 +308,6 @@ def test_values(self, args, kwargs, expected, atol):
             ((1.1, "e-"), {"T": 1.2}, 3.11737236e-08 * u.m, u.UnitsWarning),
             ((1.1 * u.T, "e-"), {"T": 1.2}, 3.11737236e-08 * u.m, u.UnitsWarning),
             ((1.1, "e-"), {"T": 1.2 * u.K}, 3.11737236e-08 * u.m, u.UnitsWarning),
-            #
-            # Future warning for using T_i instead of T
-            (
-                (1.1 * u.T, "e-"),
-                {"T_i": 1.2 * u.K},
-                3.11737236e-08 * u.m,
-                PlasmaPyFutureWarning,
-            ),
         ],
     )
     def test_warns(self, args, kwargs, expected, _warns):