英文:
ValueError: x and y must have same first dimension, but have shapes (5,) and (1,)
问题
import time
import random
import matplotlib.pyplot as plt
def brute_force(values, weights, capacity):
num_items = len(values)
max_value = 0
subset = []
for i in range(2**num_items):
current_value = 0
current_weight = 0
current_subset = []
for j in range(num_items):
if(i & (1 << j)) != 0:
current_value += values[j]
current_weight += weights[j]
current_subset.append(j)
if current_weight <= capacity and current_value > max_value:
max_value = current_value
subset = current_subset
return max_value, subset
input_sizes = [10, 20, 30, 40, 50]
running_times = []
for size in input_sizes:
values = [random.randint(1, 100) for _ in range(size)]
weights = [random.randint(1, 100) for _ in range(size)]
capacity = sum(weights) // 2
start_time = time.time()
max_value, subset = brute_force(values, weights, capacity)
end_time = time.time()
running_time = end_time - start_time
running_times.append(running_time)
print(f"Input size: {size}")
print(f"Chosen subset: {subset}")
print(f"Chosen weight: {sum(weights[i] for i in subset)}")
print(f"Running time: {running_time:.6f} seconds")
plt.plot(input_sizes, running_times, marker='o')
plt.xlabel('Input size')
plt.ylabel('Running time (s)')
plt.title('Brute force Knapsack')
plt.show()
英文:
I'm creating a brute force approach for the knapsack problem, unfortunately when trying to graph the results I get this error: ValueError: x and y must have same first dimension, but have shapes (5,) and (1,)
import time
import random
import matplotlib.pyplot as plt
def brute_force(values, weights, capacity):
num_items = len(values)
max_value = 0
subset = []
for i in range(2**num_items):
current_value = 0
current_weight = 0
current_subset = []
for j in range(num_items):
if(i & (1 << j)) != 0:
current_value += values[j]
current_weight += weights[j]
current_subset.append(j)
if current_weight <= capacity and current_value > max_value:
max_value = current_value
subset = current_subset
return max_value, subset
input_sizes = [10, 20, 30, 40, 50]
running_times = []
for size in input_sizes:
values = [random.randint(1,100) for _ in range(size)]
weights = [random.randint(1, 100) for _ in range(size)]
capacity = sum(weights) // 2
start_time = time.time()
max_value, subset = brute_force(values, weights, capacity)
end_time = time.time()
running_time = end_time - start_time
running_times.append(running_time)
print(f"Input size: {size}")
print(f"Chosen subset: {subset}")
print(f"Chosen weight: {sum(weights[i] for i in subset)}")
print(f"Running time: {running_time: .6f} seconds")
plt.plot(input_sizes, running_times, marker = 'o')
plt.xlabel('Input size')
plt.ylabel('Running time (s)')
plt.title('Brute force Knapsack')
plt.show()
答案1
得分: 0
# 在循环内部有 `plt`，这意味着 `running_times` 只有一个值，而 `input_sizes` 有 5 个值...
这样应该可以工作：
```python
import time
import random
import matplotlib.pyplot as plt
def brute_force(values, weights, capacity):
num_items = len(values)
max_value = 0
subset = []
for i in range(2**num_items):
current_value = 0
current_weight = 0
current_subset = []
for j in range(num_items):
if(i & (1 << j)) != 0:
current_value += values[j]
current_weight += weights[j]
current_subset.append(j)
if current_weight <= capacity and current_value > max_value:
max_value = current_value
subset = current_subset
return max_value, subset
input_sizes = [10, 20, 30, 40, 50]
running_times = []
for size in input_sizes:
values = [random.randint(1,100) for _ in range(size)]
weights = [random.randint(1, 100) for _ in range(size)]
capacity = sum(weights) // 2
start_time = time.time()
max_value, subset = brute_force(values, weights, capacity)
end_time = time.time()
running_time = end_time - start_time
running_times.append(running_time)
print(f"Input size: {size}")
print(f"Chosen subset: {subset}")
print(f"Chosen weight: {sum(weights[i] for i in subset)}")
print(f"Running time: {running_time: .6f} seconds")
plt.plot(input_sizes, running_times, marker = 'o')
plt.xlabel('Input size')
plt.ylabel('Running time (s)')
plt.title('Brute force Knapsack')
plt.show()
我将 input_list 减小为 [1, 2, 3, 4, 5]（为了速度，你可以将其改回），输出如下：
<details>
<summary>英文:</summary>
The `plt` was inside the loop meaning that `running_times` has only one value whereas `input_sizes` has 5 values...
This should work:
```python
import time
import random
import matplotlib.pyplot as plt
def brute_force(values, weights, capacity):
num_items = len(values)
max_value = 0
subset = []
for i in range(2**num_items):
current_value = 0
current_weight = 0
current_subset = []
for j in range(num_items):
if(i & (1 << j)) != 0:
current_value += values[j]
current_weight += weights[j]
current_subset.append(j)
if current_weight <= capacity and current_value > max_value:
max_value = current_value
subset = current_subset
return max_value, subset
input_sizes = [10, 20, 30, 40, 50]
running_times = []
for size in input_sizes:
values = [random.randint(1,100) for _ in range(size)]
weights = [random.randint(1, 100) for _ in range(size)]
capacity = sum(weights) // 2
start_time = time.time()
max_value, subset = brute_force(values, weights, capacity)
end_time = time.time()
running_time = end_time - start_time
running_times.append(running_time)
print(f"Input size: {size}")
print(f"Chosen subset: {subset}")
print(f"Chosen weight: {sum(weights[i] for i in subset)}")
print(f"Running time: {running_time: .6f} seconds")
plt.plot(input_sizes, running_times, marker = 'o')
plt.xlabel('Input size')
plt.ylabel('Running time (s)')
plt.title('Brute force Knapsack')
plt.show()
i reduced the input_list to [1, 2, 3, 4, 5] (for speed, so you can put it back) and the output looks like this:
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