线性变换

transform/trans.py

@@ -0,0 +1,42 @@
+def linear_trans2d(arr:list[list[float]],x:list[float]) -> list[float]:
+    '''
+    @param arr:
+        [
+            [a,b],
+            [c,d]
+        ]
+        
+    @param x:
+        [x1,x2]
+    
+    @return
+        arr times x
+    '''
+    return [x[0]*arr[0][0]+x[1]*arr[0][1], x[0]*arr[1][0]+x[1]*arr[1][1]]
+
+def linear_trans(arr:list[list[float]],x:list[float]) -> list[float]:
+    if len(arr) != len(x):
+        raise ValueError("Shape must be same.")
+    return [sum(map(lambda x: x[0]*x[1],zip(line,x))) for line in arr]
+
+import numpy as np
+
+def linear_trans_np(arr:np.ndarray,x:np.ndarray) -> np.ndarray:
+    if not arr.shape[0] == arr.shape[1] == x.shape[0]:
+        raise ValueError("Shape must be (k,k) and (k,)")
+    return np.array([np.sum(line * x) for line in arr])
+
+if __name__ == "__main__":
+    # check code with np
+    import numpy as np
+    np.random.seed()
+    
+    for i in range(100):
+        arr = np.random.random_sample((4,4))
+        x = np.random.random_sample((4,))
+
+        ans = np.dot(arr,x)
+        out = linear_trans_np(arr,x)
+        # print(out)
+        # out = np.array(out)
+        assert np.all(np.abs(ans-out)<0.0001)