[英]How do I read from binary file to an array of int16 in python
我正在嘗試解析一個二進制文件。 該文件包含一些數據包,每個數據包都以一個時間戳記開始,然后定義一個數組(行和列分別為int32)和數組本身。 我開始嘗試解析單個數據包,但讀取數組時遇到問題:
tsSize = 8
rowSize = 4
columnSize=4
thresholdVectorSize=4
targetsCandidatesVectorSize=4
centerOfMassVectorSize=4
bytesReadUpToNow=0
with open("C:\\outputs\\out.bin", mode='rb') as file: # b is important -> binary
fileContent = file.read()
TimeS = struct.unpack("Q", fileContent[bytesReadUpToNow:bytesReadUpToNow+tsSize])[0]
bytesReadUpToNow+=tsSize
dt =datetime.datetime.fromtimestamp(TimeS/1000.0)
rows, columns = struct.unpack("ii", fileContent[bytesReadUpToNow:bytesReadUpToNow+rowSize+columnSize])
bytesReadUpToNow=bytesReadUpToNow+rowSize+columnSize
data = struct.unpack("h" * (rows*columns), fileContent[bytesReadUpToNow:rows*columns*2+bytesReadUpToNow])[0]
print(sys.getsizeof(data))
print(type(data))
有沒有辦法在python中預定義數組的大小?
您可以使用“ bytearray”:
ba=bytearray(1000) # zero-filled
In: sys.getsizeof(ba)
Out: 1057
In: ba[0:10]
Out: bytearray(b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00')
In: ba[5]=255
In: ba[0:10]
Out: bytearray(b'\x00\x00\x00\x00\x00\xff\x00\x00\x00\x00')
編輯:
with open("data","wb") as ff:
ff.write(int.to_bytes(100,1,"big"))
ff.write(int.to_bytes(300,2,"big"))
ff.write(int.to_bytes(5001,4,"big"))
ba=bytearray(7)
ba
Out: bytearray(b'\x00\x00\x00\x00\x00\x00\x00')
with open("data","rb") as ff:
ba[0:7]= ff.read(7)
ba
Out: bytearray(b'd\x01,\x00\x00\x13\x89')
int.from_bytes(ba[0:1],"big")
Out: 100
int.from_bytes(ba[1:3],"big")
Out: 300
int.from_bytes(ba[3:],"big")
Out: 5001
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