[Docs] Translate fileio doc (#753)

* translate the fileio doc

* Update docs/en/advanced_tutorials/fileio.md

Co-authored-by: Zaida Zhou <58739961+zhouzaida@users.noreply.github.com>

* Update docs/en/advanced_tutorials/fileio.md

Co-authored-by: Zaida Zhou <58739961+zhouzaida@users.noreply.github.com>

docs/en/advanced_tutorials/fileio.md

 # File IO
 
-Coming soon. Please refer to [chinese documentation](https://mmengine.readthedocs.io/zh_CN/latest/advanced_tutorials/fileio.html).
+`MMEngine` implements a unified set of file reading and writing interfaces in `fileio` module. With the `fileio` module, we can use the same function to handle different file formats, such as `json`, `yaml` and `pickle`. Other file formats can also be easily extended.
+
+The `fileio` module also supports reading and writing files from a variety of file storage backends, including disk, Petrel (for internal use), Memcached, LMDB, and HTTP.
+
+## Load and dump data
+
+`MMEngine` provides a universal API for loading and dumping data, currently supported formats are `json`, `yaml`, and `pickle`.
+
+### Load from disk or dump to disk
+
+```python
+from mmengine import load, dump
+
+# load data from a file
+data = load('test.json')
+data = load('test.yaml')
+data = load('test.pkl')
+# load data from a file-like object
+with open('test.json', 'r') as f:
+    data = load(f, file_format='json')
+
+# dump data to a string
+json_str = dump(data, file_format='json')
+
+# dump data to a file with a filename (infer format from file extension)
+dump(data, 'out.pkl')
+
+# dump data to a file with a file-like object
+with open('test.yaml', 'w') as f:
+    data = dump(data, f, file_format='yaml')
+```
+
+### Load from other backends or dump to other backends
+
+```python
+from mmengine import load, dump
+
+# load data from a file
+data = load('s3://bucket-name/test.json')
+data = load('s3://bucket-name/test.yaml')
+data = load('s3://bucket-name/test.pkl')
+
+# dump data to a file with a filename (infer format from file extension)
+dump(data, 's3://bucket-name/out.pkl')
+```
+
+It is also very convenient to extend the API to support more file formats. All you need to do is to write a file handler inherited from `BaseFileHandler` and register it with one or several file formats.
+
+```python
+from mmengine import register_handler, BaseFileHandler
+
+# To register multiple file formats, a list can be used as the argument.
+# @register_handler(['txt', 'log'])
+@register_handler('txt')
+class TxtHandler1(BaseFileHandler):
+
+    def load_from_fileobj(self, file):
+        return file.read()
+
+    def dump_to_fileobj(self, obj, file):
+        file.write(str(obj))
+
+    def dump_to_str(self, obj, **kwargs):
+        return str(obj)
+```
+
+Here is an example of `PickleHandler`.
+
+```python
+from mmengine import BaseFileHandler
+import pickle
+
+class PickleHandler(BaseFileHandler):
+
+    def load_from_fileobj(self, file, **kwargs):
+        return pickle.load(file, **kwargs)
+
+    def load_from_path(self, filepath, **kwargs):
+        return super(PickleHandler, self).load_from_path(
+            filepath, mode='rb', **kwargs)
+
+    def dump_to_str(self, obj, **kwargs):
+        kwargs.setdefault('protocol', 2)
+        return pickle.dumps(obj, **kwargs)
+
+    def dump_to_fileobj(self, obj, file, **kwargs):
+        kwargs.setdefault('protocol', 2)
+        pickle.dump(obj, file, **kwargs)
+
+    def dump_to_path(self, obj, filepath, **kwargs):
+        super(PickleHandler, self).dump_to_path(
+            obj, filepath, mode='wb', **kwargs)
+```
+
+## Load a text file as a list or dict
+
+For example `a.txt` is a text file with 5 lines.
+
+```
+a
+b
+c
+d
+e
+```
+
+### Load from disk
+
+Use `list_from_file` to load the list from `a.txt`.
+
+```python
+from mmengine import list_from_file
+
+print(list_from_file('a.txt'))
+# ['a', 'b', 'c', 'd', 'e']
+print(list_from_file('a.txt', offset=2))
+# ['c', 'd', 'e']
+print(list_from_file('a.txt', max_num=2))
+# ['a', 'b']
+print(list_from_file('a.txt', prefix='/mnt/'))
+# ['/mnt/a', '/mnt/b', '/mnt/c', '/mnt/d', '/mnt/e']
+```
+
+For example `b.txt` is a text file with 3 lines.
+
+```
+1 cat
+2 dog cow
+3 panda
+```
+
+Then use `dict_from_file` to load the dict from `b.txt`.
+
+```python
+from mmengine import dict_from_file
+
+print(dict_from_file('b.txt'))
+# {'1': 'cat', '2': ['dog', 'cow'], '3': 'panda'}
+print(dict_from_file('b.txt', key_type=int))
+# {1: 'cat', 2: ['dog', 'cow'], 3: 'panda'}
+```
+
+### Load from other backends
+
+Use `list_from_file` to load the list from `s3://bucket-name/a.txt`.
+
+```python
+from mmengine import list_from_file
+
+print(list_from_file('s3://bucket-name/a.txt'))
+# ['a', 'b', 'c', 'd', 'e']
+print(list_from_file('s3://bucket-name/a.txt', offset=2))
+# ['c', 'd', 'e']
+print(list_from_file('s3://bucket-name/a.txt', max_num=2))
+# ['a', 'b']
+print(list_from_file('s3://bucket-name/a.txt', prefix='/mnt/'))
+# ['/mnt/a', '/mnt/b', '/mnt/c', '/mnt/d', '/mnt/e']
+```
+
+Use `dict_from_file` to load the dict from `s3://bucket-name/b.txt`.
+
+```python
+from mmengine import dict_from_file
+
+print(dict_from_file('s3://bucket-name/b.txt'))
+# {'1': 'cat', '2': ['dog', 'cow'], '3': 'panda'}
+print(dict_from_file('s3://bucket-name/b.txt', key_type=int))
+# {1: 'cat', 2: ['dog', 'cow'], 3: 'panda'}
+```
+
+## Load and dump checkpoints
+
+We can read the checkpoints from disk or internet in the following way.
+
+```python
+import torch
+
+filepath1 = '/path/of/your/checkpoint1.pth'
+filepath2 = 'http://path/of/your/checkpoint3.pth'
+
+# read filepath1 from disk
+checkpoint = torch.load(filepath1)
+# save checkpoints to disk
+torch.save(checkpoint, filepath1)
+
+# read filepath2 from internet
+checkpoint = torch.utils.model_zoo.load_url(filepath2)
+```
+
+In `MMEngine`, reading and writing checkpoints in different storage forms can be uniformly implemented with `load_checkpoint` and `save_checkpoint`.
+
+```python
+from mmengine import load_checkpoint, save_checkpoint
+
+filepath1 = '/path/of/your/checkpoint1.pth'
+filepath2 = 's3://bucket-name/path/of/your/checkpoint1.pth'
+filepath3 = 'http://path/of/your/checkpoint3.pth'
+
+# read checkpoints from disk
+checkpoint = load_checkpoint(filepath1)
+# save checkpoints from disk
+save_checkpoint(checkpoint, filepath1)
+
+# read checkpoints from s3
+checkpoint = load_checkpoint(filepath2)
+# save checkpoints from s3
+save_checkpoint(checkpoint, filepath2)
+
+# read checkpoints from internet
+checkpoint = load_checkpoint(filepath3)
+```

docs/zh_cn/advanced_tutorials/fileio.md

@@ -189,7 +189,7 @@ torch.save(checkpoint, filepath1)
 checkpoint = torch.utils.model_zoo.load_url(filepath2)
 ```
 
-在 `mmengine` 中，得益于多文件存储后端的支持，不同存储形式的权重文件读写可以通过
+在 `MMEngine` 中，得益于多文件存储后端的支持，不同存储形式的权重文件读写可以通过
 `load_checkpoint` 和 `save_checkpoint` 来统一实现。
 
 ```python