RuntimeError: OrderedDict mutated during iteration

阳光穿透心脏的1/2处 2023-02-19 13:22 5阅读 0赞

#  RuntimeError: OrderedDict mutated during iteration #

Traceback (most recent call last):
      File "/home/yongqiang/pytorch_work/end2end-asr-pytorch-example/yongqiang.py", line 18, in <module>
        for key, value in dict_data.items():
    RuntimeError: OrderedDict mutated during iteration

## 1. RuntimeError: OrderedDict mutated during iteration ##

#!/usr/bin/env python
    # -*- coding: utf-8 -*-
    # yongqiang cheng
    
    from __future__ import absolute_import
    from __future__ import division
    from __future__ import print_function
    
    from collections import OrderedDict
    
    dict_data = OrderedDict()
    dict_data['1'] = "cheng"
    dict_data['2'] = "yong"
    dict_data['3'] = "qiang"
    dict_data['4'] = "forever"
    dict_data['5'] = "strong"
    
    for key, value in dict_data.items():
        print(key + ': ' + value)
    
        if ('3' == key):
            del dict_data[key]

/home/yongqiang/miniconda3/envs/pt-1.4_py-3.6/bin/python /home/yongqiang/pytorch_work/end2end-asr-pytorch-example/yongqiang.py
    Traceback (most recent call last):
      File "/home/yongqiang/pytorch_work/end2end-asr-pytorch-example/yongqiang.py", line 18, in <module>
        for key, value in dict_data.items():
    RuntimeError: OrderedDict mutated during iteration
    1: cheng
    2: yong
    3: qiang
    
    Process finished with exit code 1

## 2. The issue is that `dict_data.items()` does not return a copy, so it should not be modified while iterating. ##

Python 中赋值语句不复制对象，而是在目标和对象之间创建绑定 (bindings) 关系。对于自身可变或者包含可变项的集合对象，开发者有时会需要生成其副本用于改变操作，进而避免改变原对象。

#!/usr/bin/env python
    # -*- coding: utf-8 -*-
    # yongqiang cheng
    
    from __future__ import absolute_import
    from __future__ import division
    from __future__ import print_function
    
    from collections import OrderedDict
    
    dict_data = OrderedDict()
    dict_data['1'] = "cheng"
    dict_data['2'] = "yong"
    dict_data['3'] = "qiang"
    dict_data['4'] = "forever"
    dict_data['5'] = "strong"
    
    for key, value in list(dict_data.items()):
        print(key + ': ' + value)
    
        if ('3' == key):
            del dict_data[key]
    
    print()
    
    for key, value in list(dict_data.items()):
        print(key + ': ' + value)

/home/yongqiang/miniconda3/envs/pt-1.4_py-3.6/bin/python /home/yongqiang/pytorch_work/end2end-asr-pytorch-example/yongqiang.py
    1: cheng
    2: yong
    3: qiang
    4: forever
    5: strong
    
    1: cheng
    2: yong
    4: forever
    5: strong
    
    Process finished with exit code 0