| """Read and write for the RecordIO data format.""" |
| from __future__ import absolute_import |
| from collections import namedtuple |
| |
| import ctypes |
| import struct |
| import numbers |
| import numpy as np |
| |
| from .base import _LIB |
| from .base import RecordIOHandle |
| from .base import check_call |
| from .base import c_str |
| try: |
| import cv2 |
| except ImportError: |
| cv2 = None |
| |
| class MXRecordIO(object): |
| """Reads/writes `RecordIO` data format, supporting sequential read and write. |
| |
| Example usage: |
| ---------- |
| >>> record = mx.recordio.MXRecordIO('tmp.rec', 'w') |
| <mxnet.recordio.MXRecordIO object at 0x10ef40ed0> |
| >>> for i in range(5): |
| ... record.write('record_%d'%i) |
| >>> record.close() |
| >>> record = mx.recordio.MXRecordIO('tmp.rec', 'r') |
| >>> for i in range(5): |
| ... item = record.read() |
| ... print(item) |
| record_0 |
| record_1 |
| record_2 |
| record_3 |
| record_4 |
| >>> record.close() |
| |
| Parameters |
| ---------- |
| uri : string |
| Path to the record file. |
| flag : string |
| 'w' for write or 'r' for read. |
| """ |
| def __init__(self, uri, flag): |
| self.uri = c_str(uri) |
| self.handle = RecordIOHandle() |
| self.flag = flag |
| self.is_open = False |
| self.open() |
| |
| def open(self): |
| """Opens the record file.""" |
| if self.flag == "w": |
| check_call(_LIB.MXRecordIOWriterCreate(self.uri, ctypes.byref(self.handle))) |
| self.writable = True |
| elif self.flag == "r": |
| check_call(_LIB.MXRecordIOReaderCreate(self.uri, ctypes.byref(self.handle))) |
| self.writable = False |
| else: |
| raise ValueError("Invalid flag %s"%self.flag) |
| self.is_open = True |
| |
| def __del__(self): |
| self.close() |
| |
| def close(self): |
| """Closes the record file.""" |
| if not self.is_open: |
| return |
| if self.writable: |
| check_call(_LIB.MXRecordIOWriterFree(self.handle)) |
| else: |
| check_call(_LIB.MXRecordIOReaderFree(self.handle)) |
| self.is_open = False |
| |
| def reset(self): |
| """Resets the pointer to first item. |
| |
| If the record is opened with 'w', this function will truncate the file to empty. |
| |
| Example usage: |
| ---------- |
| >>> record = mx.recordio.MXRecordIO('tmp.rec', 'r') |
| >>> for i in range(2): |
| ... item = record.read() |
| ... print(item) |
| record_0 |
| record_1 |
| >>> record.reset() # Pointer is reset. |
| >>> print(record.read()) # Started reading from start again. |
| record_0 |
| >>> record.close() |
| """ |
| self.close() |
| self.open() |
| |
| def write(self, buf): |
| """Inserts a string buffer as a record. |
| |
| Example usage: |
| ---------- |
| >>> record = mx.recordio.MXRecordIO('tmp.rec', 'w') |
| >>> for i in range(5): |
| ... record.write('record_%d'%i) |
| >>> record.close() |
| |
| Parameters |
| ---------- |
| buf : string (python2), bytes (python3) |
| Buffer to write. |
| """ |
| assert self.writable |
| check_call(_LIB.MXRecordIOWriterWriteRecord(self.handle, |
| ctypes.c_char_p(buf), |
| ctypes.c_size_t(len(buf)))) |
| |
| def read(self): |
| """Returns record as a string. |
| |
| Example usage: |
| ---------- |
| >>> record = mx.recordio.MXRecordIO('tmp.rec', 'r') |
| >>> for i in range(5): |
| ... item = record.read() |
| ... print(item) |
| record_0 |
| record_1 |
| record_2 |
| record_3 |
| record_4 |
| >>> record.close() |
| |
| Returns |
| ---------- |
| buf : string |
| Buffer read. |
| """ |
| assert not self.writable |
| buf = ctypes.c_char_p() |
| size = ctypes.c_size_t() |
| check_call(_LIB.MXRecordIOReaderReadRecord(self.handle, |
| ctypes.byref(buf), |
| ctypes.byref(size))) |
| if buf: |
| buf = ctypes.cast(buf, ctypes.POINTER(ctypes.c_char*size.value)) |
| return buf.contents.raw |
| else: |
| return None |
| |
| class MXIndexedRecordIO(MXRecordIO): |
| """Reads/writes `RecordIO` data format, supporting random access. |
| |
| Example usage: |
| ---------- |
| >>> for i in range(5): |
| ... record.write_idx(i, 'record_%d'%i) |
| >>> record.close() |
| >>> record = mx.recordio.MXIndexedRecordIO('tmp.idx', 'tmp.rec', 'r') |
| >>> record.read_idx(3) |
| record_3 |
| |
| Parameters |
| ---------- |
| idx_path : str |
| Path to the index file. |
| uri : str |
| Path to the record file. Only supports seekable file types. |
| flag : str |
| 'w' for write or 'r' for read. |
| key_type : type |
| Data type for keys. |
| """ |
| def __init__(self, idx_path, uri, flag, key_type=int): |
| self.idx_path = idx_path |
| self.idx = {} |
| self.keys = [] |
| self.key_type = key_type |
| self.fidx = None |
| super(MXIndexedRecordIO, self).__init__(uri, flag) |
| |
| def open(self): |
| super(MXIndexedRecordIO, self).open() |
| self.idx = {} |
| self.keys = [] |
| self.fidx = open(self.idx_path, self.flag) |
| if not self.writable: |
| for line in iter(self.fidx.readline, ''): |
| line = line.strip().split('\t') |
| key = self.key_type(line[0]) |
| self.idx[key] = int(line[1]) |
| self.keys.append(key) |
| |
| def close(self): |
| """Closes the record file.""" |
| if not self.is_open: |
| return |
| super(MXIndexedRecordIO, self).close() |
| self.fidx.close() |
| |
| def seek(self, idx): |
| """Sets the current read pointer position. |
| |
| This function is internally called by `read_idx(idx)` to find the current |
| reader pointer position. It doesn't return anything.""" |
| assert not self.writable |
| pos = ctypes.c_size_t(self.idx[idx]) |
| check_call(_LIB.MXRecordIOReaderSeek(self.handle, pos)) |
| |
| def tell(self): |
| """Returns the current position of write head. |
| |
| Example usage: |
| ---------- |
| >>> record = mx.recordio.MXIndexedRecordIO('tmp.idx', 'tmp.rec', 'w') |
| >>> print(record.tell()) |
| 0 |
| >>> for i in range(5): |
| ... record.write_idx(i, 'record_%d'%i) |
| ... print(record.tell()) |
| 16 |
| 32 |
| 48 |
| 64 |
| 80 |
| """ |
| assert self.writable |
| pos = ctypes.c_size_t() |
| check_call(_LIB.MXRecordIOWriterTell(self.handle, ctypes.byref(pos))) |
| return pos.value |
| |
| def read_idx(self, idx): |
| """Returns the record at given index. |
| |
| Example usage: |
| ---------- |
| >>> record = mx.recordio.MXIndexedRecordIO('tmp.idx', 'tmp.rec', 'w') |
| >>> for i in range(5): |
| ... record.write_idx(i, 'record_%d'%i) |
| >>> record.close() |
| >>> record = mx.recordio.MXIndexedRecordIO('tmp.idx', 'tmp.rec', 'r') |
| >>> record.read_idx(3) |
| record_3 |
| """ |
| self.seek(idx) |
| return self.read() |
| |
| def write_idx(self, idx, buf): |
| """Inserts input record at given index. |
| |
| Example usage: |
| ---------- |
| >>> for i in range(5): |
| ... record.write_idx(i, 'record_%d'%i) |
| >>> record.close() |
| |
| Parameters |
| ---------- |
| idx : int |
| Index of a file. |
| buf : |
| Record to write. |
| """ |
| key = self.key_type(idx) |
| pos = self.tell() |
| self.write(buf) |
| self.fidx.write('%s\t%d\n'%(str(key), pos)) |
| self.idx[key] = pos |
| self.keys.append(key) |
| |
| |
| IRHeader = namedtuple('HEADER', ['flag', 'label', 'id', 'id2']) |
| """An alias for HEADER. Used to store metadata (e.g. labels) accompanying a record. |
| See mxnet.recordio.pack and mxnet.recordio.pack_img for example uses. |
| |
| Parameters |
| ---------- |
| flag : int |
| Available for convenience, can be set arbitrarily. |
| label : float or an array of float |
| Typically used to store label(s) for a record. |
| id: int |
| Usually a unique id representing record. |
| id2: int |
| Higher order bits of the unique id, should be set to 0 (in most cases). |
| """ |
| _IR_FORMAT = 'IfQQ' |
| _IR_SIZE = struct.calcsize(_IR_FORMAT) |
| |
| def pack(header, s): |
| """Pack a string into MXImageRecord. |
| |
| Parameters |
| ---------- |
| header : IRHeader |
| Header of the image record. |
| ``header.label`` can be a number or an array. See more detail in ``IRHeader``. |
| s : str |
| Raw image string to be packed. |
| |
| Returns |
| ------- |
| s : str |
| The packed string. |
| |
| Examples |
| -------- |
| >>> label = 4 # label can also be a 1-D array, for example: label = [1,2,3] |
| >>> id = 2574 |
| >>> header = mx.recordio.IRHeader(0, label, id, 0) |
| >>> with open(path, 'r') as file: |
| ... s = file.read() |
| >>> packed_s = mx.recordio.pack(header, s) |
| """ |
| header = IRHeader(*header) |
| if isinstance(header.label, numbers.Number): |
| header = header._replace(flag=0) |
| else: |
| label = np.asarray(header.label, dtype=np.float32) |
| header = header._replace(flag=label.size, label=0) |
| s = label.tostring() + s |
| s = struct.pack(_IR_FORMAT, *header) + s |
| return s |
| |
| def unpack(s): |
| """Unpack a MXImageRecord to string. |
| |
| Parameters |
| ---------- |
| s : str |
| String buffer from ``MXRecordIO.read``. |
| |
| Returns |
| ------- |
| header : IRHeader |
| Header of the image record. |
| s : str |
| Unpacked string. |
| |
| Examples |
| -------- |
| >>> record = mx.recordio.MXRecordIO('test.rec', 'r') |
| >>> item = record.read() |
| >>> header, s = mx.recordio.unpack(item) |
| >>> header |
| HEADER(flag=0, label=14.0, id=20129312, id2=0) |
| """ |
| header = IRHeader(*struct.unpack(_IR_FORMAT, s[:_IR_SIZE])) |
| s = s[_IR_SIZE:] |
| if header.flag > 0: |
| header = header._replace(label=np.fromstring(s, np.float32, header.flag)) |
| s = s[header.flag*4:] |
| return header, s |
| |
| def unpack_img(s, iscolor=-1): |
| """Unpack a MXImageRecord to image. |
| |
| Parameters |
| ---------- |
| s : str |
| String buffer from ``MXRecordIO.read``. |
| iscolor : int |
| Image format option for ``cv2.imdecode``. |
| |
| Returns |
| ------- |
| header : IRHeader |
| Header of the image record. |
| img : numpy.ndarray |
| Unpacked image. |
| |
| Examples |
| -------- |
| >>> record = mx.recordio.MXRecordIO('test.rec', 'r') |
| >>> item = record.read() |
| >>> header, img = mx.recordio.unpack_img(item) |
| >>> header |
| HEADER(flag=0, label=14.0, id=20129312, id2=0) |
| >>> img |
| array([[[ 23, 27, 45], |
| [ 28, 32, 50], |
| ..., |
| [ 36, 40, 59], |
| [ 35, 39, 58]], |
| ..., |
| [[ 91, 92, 113], |
| [ 97, 98, 119], |
| ..., |
| [168, 169, 167], |
| [166, 167, 165]]], dtype=uint8) |
| """ |
| header, s = unpack(s) |
| img = np.fromstring(s, dtype=np.uint8) |
| assert cv2 is not None |
| img = cv2.imdecode(img, iscolor) |
| return header, img |
| |
| def pack_img(header, img, quality=95, img_fmt='.jpg'): |
| """Pack an image into ``MXImageRecord``. |
| |
| Parameters |
| ---------- |
| header : IRHeader |
| Header of the image record. |
| ``header.label`` can be a number or an array. See more detail in ``IRHeader``. |
| img : numpy.ndarray |
| Image to be packed. |
| quality : int |
| Quality for JPEG encoding in range 1-100, or compression for PNG encoding in range 1-9. |
| img_fmt : str |
| Encoding of the image (.jpg for JPEG, .png for PNG). |
| |
| Returns |
| ------- |
| s : str |
| The packed string. |
| |
| Examples |
| -------- |
| >>> label = 4 # label can also be a 1-D array, for example: label = [1,2,3] |
| >>> id = 2574 |
| >>> header = mx.recordio.IRHeader(0, label, id, 0) |
| >>> img = cv2.imread('test.jpg') |
| >>> packed_s = mx.recordio.pack_img(header, img) |
| """ |
| assert cv2 is not None |
| jpg_formats = ['.JPG', '.JPEG'] |
| png_formats = ['.PNG'] |
| encode_params = None |
| if img_fmt.upper() in jpg_formats: |
| encode_params = [cv2.IMWRITE_JPEG_QUALITY, quality] |
| elif img_fmt.upper() in png_formats: |
| encode_params = [cv2.IMWRITE_PNG_COMPRESSION, quality] |
| |
| ret, buf = cv2.imencode(img_fmt, img, encode_params) |
| assert ret, 'failed to encode image' |
| return pack(header, buf.tostring()) |
