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Can't use locals() in list comprehension in Python 3?（1个答案）
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当调用这个模块中的示例函数func时，为什么当我使用理解时它会抛出异常（可以用参数切换）？有人能解释一下异常的含义吗？cycle似乎被覆盖了，我无法理解它。

与循环和理解功能相同的示例函数

import pandas as pd

def func(
    x_dict,
    keys_list,
    start_cycle,
    end_cycle,
    comprehension=True
):
    x_test_dicts = {}
    for cycle in range(start_cycle, end_cycle + 1):
        print(f"cycle = {cycle}")
        if comprehension:
            # Fill the dict with comprehension.
            x_test_dict = {
                f"{key}_input":
                x_dict[key].query('cycle == @cycle').values
                for key in keys_list
            }
        else:
            # Fill the dict with normal for loop.
            x_test_dict = {}
            for key in keys_list:
                x_test_dict[f"{key}_input"] = \
                    x_dict[key].query('cycle == @cycle').values
        x_test_dicts[cycle] = x_test_dict
    return x_test_dicts

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创建测试数据

import pandas as pd
import numpy as np

# Create an ID array from 1 to 1000
ids = np.arange(1, 1001)

# Calculate cycle as ID divided by 100
cycles = ids // 100

# Generate random integer values for the remaining columns
# Assuming a range for random integers (e.g., 0 to 100)
col1_int = np.random.randint(0, 101, 1000)
col2_int = np.random.randint(0, 101, 1000)
col3_int = np.random.randint(0, 101, 1000)

# Update the DataFrame with integer values
df = pd.DataFrame({
    "ID": ids,
    "cycle": cycles,
    "col1": col1_int,
    "col2": col2_int,
    "col3": col3_int
})

df.head()  # Display the first few rows of the updated DataFrame

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使用函数运行测试用例

import pandas as pd

df = df.set_index(['ID', 'cycle'])  # Use multi-indexing

x_dict = {'Auxin': df}  # Create a simple dict with the DataFrame
keys_list = ['Auxin']  # Define a list of keys to work with

# Define ranges for the loop inside `func`
start_cycle = 6
end_cycle = 29

# RUNS SUCCESSFULLY WITHOUT LIST COMPREHENSION
comprehension = False
result = func(
    x_dict,
    keys_list,
    start_cycle,
    end_cycle,
    comprehension=comprehension
)
print("Worked without dict comprehension!")

# FAILS WITH LIST COMPREHENSION
comprehension = True
result = func(
    x_dict,
    keys_list,
    start_cycle,
    end_cycle,
    comprehension=comprehension
)
print("Breaks when dict comprehension is used!")

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错误

UndefinedVariableError: local variable 'cycle' is not defined

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