214 lines
5.7 KiB
Markdown
214 lines
5.7 KiB
Markdown
# File IO
|
|
|
|
`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 checkpoints from disk
|
|
checkpoint = torch.load(filepath1)
|
|
# save checkpoints to disk
|
|
torch.save(checkpoint, filepath1)
|
|
|
|
# read checkpoints 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 to disk
|
|
save_checkpoint(checkpoint, filepath1)
|
|
|
|
# read checkpoints from s3
|
|
checkpoint = load_checkpoint(filepath2)
|
|
# save checkpoints to s3
|
|
save_checkpoint(checkpoint, filepath2)
|
|
|
|
# read checkpoints from internet
|
|
checkpoint = load_checkpoint(filepath3)
|
|
```
|