Colab中出现NameError: name 'Dict' is not defined错误的解决咨询

错误原因 #

函数参数的类型提示里用到的Dict和List属于Python typing模块的类型注解工具，默认未被导入，所以解释器无法识别这两个名称，触发了NameError。

两种解决方法 #

方法1：导入typing模块中的对应类型

在代码最顶部添加导入语句，同时别忘了导入绘图依赖的matplotlib库：

from typing import Dict, List
import matplotlib.pyplot as plt

def loss_metric_curve_plot(model_results:Dict[str,List[float]]):
    train_loss = model_results["train_loss"]
    valid_loss = model_results["valid_loss"]

    train_accuracy = [float(value) for value in model_results["train_accuracy"]]
    valid_accuracy = [float(value) for value in model_results["valid_accuracy"]]

    fig,axes = plt.subplots(nrows = 1, ncols = 2, figsize = (10,4))
    axes = axes.flat

    axes[0].plot(train_loss, color = "red", label = "Train")
    axes[0].plot(valid_loss, color = "blue", label = "Valid")
    axes[0].set_title("CrossEntropyLoss", fontsize = 12, fontweight = "bold", color = "black")
    axes[0].set_xlabel("Epochs", fontsize = 10, fontweight = "bold", color = "black")
    axes[0].set_ylabel("Loss", fontsize = 10, fontweight = "bold", color = "black")
    axes[0].legend()

    axes[1].plot(train_accuracy, color = "red", label = "Train")
    axes[1].plot(valid_accuracy, color = "blue", label = "Valid")
    axes[1].set_title("Metric of performance: Accuracy", fontsize = 12, fontweight = "bold", color = "black")
    axes[1].set_xlabel("Epochs", fontsize = 10, fontweight = "bold", color = "black")
    axes[1].set_ylabel("Score", fontsize = 10, fontweight = "bold", color = "black")
    axes[1].legend()

    fig.tight_layout()
    fig.show()

方法2：使用Python 3.9+内置的类型注解（无需导入）

如果你的Colab环境使用Python 3.9及以上版本，可以直接用内置的dict和list替代Dict和List，省去导入步骤：

import matplotlib.pyplot as plt

def loss_metric_curve_plot(model_results:dict[str,list[float]]):
    train_loss = model_results["train_loss"]
    valid_loss = model_results["valid_loss"]

    train_accuracy = [float(value) for value in model_results["train_accuracy"]]
    valid_accuracy = [float(value) for value in model_results["valid_accuracy"]]

    fig,axes = plt.subplots(nrows = 1, ncols = 2, figsize = (10,4))
    axes = axes.flat

    axes[0].plot(train_loss, color = "red", label = "Train")
    axes[0].plot(valid_loss, color = "blue", label = "Valid")
    axes[0].set_title("CrossEntropyLoss", fontsize = 12, fontweight = "bold", color = "black")
    axes[0].set_xlabel("Epochs", fontsize = 10, fontweight = "bold", color = "black")
    axes[0].set_ylabel("Loss", fontsize = 10, fontweight = "bold", color = "black")
    axes[0].legend()

    axes[1].plot(train_accuracy, color = "red", label = "Train")
    axes[1].plot(valid_accuracy, color = "blue", label = "Valid")
    axes[1].set_title("Metric of performance: Accuracy", fontsize = 12, fontweight = "bold", color = "black")
    axes[1].set_xlabel("Epochs", fontsize = 10, fontweight = "bold", color = "black")
    axes[1].set_ylabel("Score", fontsize = 10, fontweight = "bold", color = "black")
    axes[1].legend()

    fig.tight_layout()
    fig.show()

额外提醒 #

Colab默认已安装matplotlib，但代码必须导入matplotlib.pyplot as plt，否则后续绘图代码会触发新的NameError。

内容的提问来源于stack exchange，提问作者nesly