下面是一个脚本,显示如何正确读取数据集格式。
但是,目前它不能正确读取所有数据。这是因为PyQt没有直接支持的QList<double>
和QVector<QPointF>
模板类。在代码中,我使用了readQVariantList
来代替读取这些类型所需的缺失PyQt方法。
UPDATE:
我问了一下PyQt的邮件列表中的任意处理模板类,和author of PyQt confirmed没有办法做到这一点。所以看起来唯一的选择是用C++编写某种转换工具。
UPDATE2:
看来我太早说话,因为我现在已经发现了一种变通。 datastream format比我想象的要简单得多,因此阅读任意模板类可以简化为一个简单的算法 - 基本上,读取长度为uint32
,然后遍历range
并逐个读取包含的元素到一个list
:
points = []
length = stream.readUInt32()
for index in range(length):
point = QPoint()
stream >> point
points.append(point)
下面是脚本的修订版本:
from PyQt4 import QtCore, QtGui
FLAG_HASSOURCE = 0x0001
FLAG_HASROLE = 0x0002
FLAG_HASCOLOR = 0x0004
FLAG_HASID = 0x0008
FLAG_COMPRESS = 0x0010
FLAG_HASTHRESHOLDS = 0x0020
FLAG_HASUNITS = 0x0040
FLAG_HASCREATORIDS = 0x0080
FLAG_HASHIDDEN = 0x0100
FLAG_HASMETADATA = 0x0200
MAGIC_NUMBER = 0x46474247
FILE_VERSION = 1
DATASET_MARKER = 0x44415441
DATASET_MAGIC = 0x53455455
def read_data(path):
infile = QtCore.QFile(path)
if not infile.open(QtCore.QIODevice.ReadOnly):
raise IOError(infile.errorString())
stream = QtCore.QDataStream(infile)
magic = stream.readUInt32()
if magic != MAGIC_NUMBER:
raise IOError('invalid magic number')
version = stream.readUInt32()
if version != FILE_VERSION:
raise IOError('invalid file version')
marker = stream.readUInt32()
if marker != DATASET_MARKER:
raise IOError('invalid dataset marker')
count = stream.readInt32()
if count < 1:
raise IOError('invalid dataset count')
stream.setVersion(QtCore.QDataStream.Qt_4_7)
rows = []
while not stream.atEnd():
row = []
magic = stream.readUInt32()
if magic != DATASET_MAGIC:
raise IOError('invalid dataset magic number')
row.append(('Name', stream.readQString()))
flags = stream.readUInt32()
row.append(('Flags', flags))
if flags & FLAG_HASID:
row.append(('ID', stream.readQString()))
if flags & FLAG_HASCOLOR:
color = QtGui.QColor()
stream >> color
row.append(('Color', color))
if flags & FLAG_HASUNITS:
row.append(('Units', stream.readInt32()))
if flags & FLAG_HASCREATORIDS:
row.append(('Creators', stream.readQStringList()))
if flags & FLAG_HASHIDDEN:
row.append(('Hidden', stream.readBool()))
if flags & FLAG_HASTHRESHOLDS:
thresholds = []
length = stream.readUInt32()
for index in range(length):
thresholds.append(stream.readDouble())
row.append(('Thresholds', thresholds))
if flags & FLAG_HASSOURCE:
row.append(('Source', stream.readQString()))
if flags & FLAG_HASROLE:
row.append(('Role', stream.readInt32()))
points = []
length = stream.readUInt32()
for index in range(length):
point = QtCore.QPointF()
stream >> point
points.append(point)
row.append(('Points', points))
rows.append(row)
infile.close()
return rows
rows = read_data('datasets.bin')
for index, row in enumerate(rows):
print('Row %s:' % index)
for key, data in row:
if isinstance(data, list) and len(data):
print(' %s = [%s ... ] (%s items)' % (
key, repr(data[:3])[1:-1], len(data)))
else:
print(' %s = %s' % (key, data))
难道是最容易使用QDataStream,如与Qt Python绑定? –
https://dl.dropboxusercontent.com/u/28824868/datasets.bin这里是任何人想要测试的数据集文件的链接 –
@MichaelBawol。我试图用C++读取该文件,并且在第一个“Source”条目处失败。所以格式不完整/错误或文件损坏。你从哪里得到这些文件?你有一个具有一套已知价值的小玩具的例子吗? – ekhumoro