51 lines
1.4 KiB
Python
51 lines
1.4 KiB
Python
# 列表推导式
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x = [[1,2,3], [4,5,6], [7,8,9]]
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y = [num for i in x for num in i]
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print(f"y = [num for i in x for num in i] :{y}")
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y = []
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for i in x:
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for num in i:
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y.append(num)
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print(y)
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# 过滤不符合条件的元素 从列表中选择符合条件的元素组成新的列表
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print('过滤不符合条件的元素 从列表中选择符合条件的元素组成新的列表'.center(50,'*'))
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x = [-1,-4,6,7.5,-2.3,9,-11]
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y = [i for i in x if i>0]
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print(y)
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x = [[x, y] for x in range(3) for y in range(3)]
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print("[(x, y) for x in range(3) for y in range(3)]: ",x)
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x = [(x, y) for x in [1, 2, 3] for y in [3, 1, 4] if x != y]
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print("[(x, y) for x in [1, 2, 3] for y in [3, 1, 4] if x != y]: ",x)
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import numpy as np
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x1 = [[x] for x in range(3)]
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print("x1 = [[x] for x in range(3)] ",x1)
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x2 = [x for x in range(3)]
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print("[x2= x for x in range(3)] ",x2)
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x3 = [np.random.randn(ch1) for ch1 in [4]]
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print("x3 = ",x3)
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x4 = [np.random.randn(ch1) for ch1 in [4,1,5]]
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print("x4 = ",x4)
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x5 = np.random.random((4,1))
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print("x5 = ",x5)
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np.random.seed(1)
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x6 = [np.random.randn(ch1,ch2) for ch1,ch2 in zip([4],[1])]
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print("x6 = ",x6)
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w7 = [np.random.randn(ch1) for ch1 in ([4,2])]
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print("w7 = ",w7)
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# 注意： ch1 的列要与 ch2 行相同
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w8 = [np.random.randn(ch1, ch2) for ch1, ch2 in zip([2,3], [3,1])]
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print("w8 = ",w8)
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w8 = [np.random.randn(ch1, ch2) for ch1, ch2 in zip([2,3], [3,1])]
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print("w8 = ",w8)
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