tests for interp routine, plus new vector routine

eht_met_forecast/am.py

@@ -3,6 +3,7 @@
 import math
 import os
 import sys
+import math
 
 from .constants import LEVELS, GFS_DAY, LATLON_DELTA
 from .latlon import box
@@ -42,6 +43,17 @@ def grid_interp(a, u, v):
           + a[0][1] * (1.0 - u) * v         + a[1][1] * u * v       )
 
 
+def grid_interp_vector(a, b, u, v):
+    c = [None, None]
+    c[0] = [None, None]
+    c[1] = [None, None]
+    for i in range(0, 2):
+        for j in range(0, 2):
+            c[i][j] = math.sqrt(a[i][j]**2 + b[i][j]**2)
+
+    return grid_interp(c, u, v)
+
+
 # Numerical and physical constants
 BADVAL              = -99999.  # placeholder for missing or undefined data
 BADVAL_TEST         = -99998.

tests/unit/test_am.py

@@ -0,0 +1,52 @@
+from pytest import approx
+from math import sqrt
+
+from eht_met_forecast import am
+
+
+def test_grid_interp():
+    t = [[1, 2], [3, 4]]
+    u, v = .1, .1
+    assert am.grid_interp(t, u, v) == approx(1.3)
+
+    t = [[0, 1], [0, 1]]
+    u, v = .1, .1
+    # 0 + 0 + 1*.9*.1 + 1*.1*.1 = .09+.01
+    assert am.grid_interp(t, u, v) == approx(0.1)
+    u, v = .1, .2
+    # 0 + 0 + 1*.9*.2 + 1*.1*.2 = .18+.02 = 0.2
+    assert am.grid_interp(t, u, v) == approx(0.2)
+    u, v = .2, .1
+    # 0 + 0 + 1*.8*.1 + 1*.2*.1 = .08 + .02 = 0.1
+    assert am.grid_interp(t, u, v) == approx(0.1)
+
+    assert am.grid_interp(t, 0.1, 0.1) * 2.0 == approx(am.grid_interp(t, 0.2, 0.2)), 'diagonal is a line'
+
+    t = [[0, 1], [1, 1]]  # symmetric in u,v
+    u, v = .1, .3
+    assert am.grid_interp(t, u, v) == approx(am.grid_interp(t, v, u)), 'symmetric, is symmetric'
+    assert am.grid_interp(t, 0.1, 0.0) * 2.0 == approx(am.grid_interp(t, 0.2, 0.0)), 'symmetric, edges are lines'
+
+    t = [[0, 1], [1, 2]]  # flat
+    u, v = .1, .3
+    assert am.grid_interp(t, u, v) == approx(am.grid_interp(t, v, u)), 'flat, is symmetric'
+
+    assert am.grid_interp(t, 0.1, 0.1) * 2.0 == approx(am.grid_interp(t, 0.2, 0.2)), 'flat, diagonal is a line'
+    assert am.grid_interp(t, 0.1, 0.0) * 2.0 == approx(am.grid_interp(t, 0.2, 0.0)), 'flat, edges are lines'
+
+
+def test_grid_interp_vector():
+    t1 = [[1, 2], [3, 4]]
+    t2 = [[1, 2], [3, 4]]
+    u, v = .1, .1
+    assert am.grid_interp_vector(t1, t2, u, v) == approx(1.8384776)
+
+    c = [[sqrt(2.), sqrt(8.)], [sqrt(18.), sqrt(32.)]]
+    assert am.grid_interp(c, u, v) == approx(1.8384776)
+
+    assert am.grid_interp_vector(t1, t2, u, v) == am.grid_interp(c, u, v)
+
+    t1 = [[0, 1], [0, 1]]
+    t2 = [[0, 1], [0, 1]]
+    u, v = .1, .1
+    assert am.grid_interp_vector(t1, t2, u, v) == approx(0.1 * sqrt(2.))