[Numpy-discussion] Reading 12bits numbers ?
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 Hi, Is it possible to read an array of 12bit encoded numbers from file (or string) using numpy ? Thanks, Martin -BEGIN PGP SIGNATURE- Version: GnuPG v1.4.9 (GNU/Linux) Comment: Using GnuPG with Fedora - http://enigmail.mozdev.org/ iQEcBAEBAgAGBQJMDjG6AAoJEBdvyODiyJI4ksQH/01OMIm59V3XDpcWv6oYTSBw zFZ/Q7mtyvHhTC9LQAgBWsIrdVze2qZP8Azsv73VjHx8QggTI8Z++U7v1HuHNyhs CAT7DsSLYKcNC4sZ2tCkMNfTQZ8Xm0hTxObylr+V98LcPO+CSjRyERZSA0S3+X6A xPZlRKLNErIGqMWiyr25r7wjuYPTK8iICqYdzZI33w7eZPcMtvP40GNDUaG7aOno mcMwSzPHnKHCuPlfj3p2rCkDs5OEhmEP9fobVIhR0Y7LxusrewPuTlwL1M+e/tqe Uf0Drjymo9i3d0VqCKAKBwd9d0kJPzVCbbwQnynu87cOj9CjwhiZ4lFufc+S+m4= =CrwA -END PGP SIGNATURE- attachment: martin_raspaud.vcf___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
Re: [Numpy-discussion] Reading 12bits numbers ?
You can. If each number occupies 2 bytes (16 bits) it is straight forward. If it is a continues 12 bits stream you have to unpack by your self: data = np.fromstring(str12bits, dtype=np.uint8) data1 = data.astype(no.uint16) data1[::3] = data1[::3]*256 + data1[1::3] // 16 data1[1::3] = (data[1::3] 0x0f)*16 + data[2::3] If you have even number of 12 bits you can continue as the follows: result = np.ravel(data1.reshape(-1,3)[:,:2]) I might have mistakes, but I hope you grasped the idea. Nadav -Original Message- From: numpy-discussion-boun...@scipy.org on behalf of Martin Raspaud Sent: Tue 08-Jun-10 15:04 To: Discussion of Numerical Python Subject: [Numpy-discussion] Reading 12bits numbers ? -BEGIN PGP SIGNED MESSAGE- Hash: SHA1 Hi, Is it possible to read an array of 12bit encoded numbers from file (or string) using numpy ? Thanks, Martin -BEGIN PGP SIGNATURE- Version: GnuPG v1.4.9 (GNU/Linux) Comment: Using GnuPG with Fedora - http://enigmail.mozdev.org/ iQEcBAEBAgAGBQJMDjG6AAoJEBdvyODiyJI4ksQH/01OMIm59V3XDpcWv6oYTSBw zFZ/Q7mtyvHhTC9LQAgBWsIrdVze2qZP8Azsv73VjHx8QggTI8Z++U7v1HuHNyhs CAT7DsSLYKcNC4sZ2tCkMNfTQZ8Xm0hTxObylr+V98LcPO+CSjRyERZSA0S3+X6A xPZlRKLNErIGqMWiyr25r7wjuYPTK8iICqYdzZI33w7eZPcMtvP40GNDUaG7aOno mcMwSzPHnKHCuPlfj3p2rCkDs5OEhmEP9fobVIhR0Y7LxusrewPuTlwL1M+e/tqe Uf0Drjymo9i3d0VqCKAKBwd9d0kJPzVCbbwQnynu87cOj9CjwhiZ4lFufc+S+m4= =CrwA -END PGP SIGNATURE- winmail.dat___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
Re: [Numpy-discussion] Reading 12bits numbers ?
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 Nadav Horesh skrev: You can. If each number occupies 2 bytes (16 bits) it is straight forward. If it is a continues 12 bits stream you have to unpack by your self: data = np.fromstring(str12bits, dtype=np.uint8) data1 = data.astype(no.uint16) data1[::3] = data1[::3]*256 + data1[1::3] // 16 data1[1::3] = (data[1::3] 0x0f)*16 + data[2::3] If you have even number of 12 bits you can continue as the follows: result = np.ravel(data1.reshape(-1,3)[:,:2]) I might have mistakes, but I hope you grasped the idea. Thanks a lot. I was more thinking along the lines of having a special dtype that would read 12 bits at a time, but I couldn't find anything, and you confirmed that I had to unpack myself. I'll try your solution, thanks again, Martin -BEGIN PGP SIGNATURE- Version: GnuPG v1.4.9 (GNU/Linux) Comment: Using GnuPG with Fedora - http://enigmail.mozdev.org/ iQEcBAEBAgAGBQJMDluwAAoJEBdvyODiyJI4/A4H/RraUFD/aQHqUxttufT042IZ f1khHhkCJ4STZcNqHOMRg47c/VbaECRPg6xGkt1Gst0dtf3sr9BheAl47Iwr/J3e YVwu/Q6Pu185ydvJ9b5JkwOwYZw5tNyMY7nRluyAjIJwx6E8ZehlI27K7fcxxWng K0CnuV5dQPPNOoun4eC0OdCtZnGhAi4vEgeK4C9ZX+0fTkVmhLLlAbpLmRmKvMPb VwXD0fBkIqai3uP0VQ6KjAWFZJ8IHeZM9CzDoz11SBnwQRGfQEP+0O4p8IS6FB1V V8IrcVAgztq3BaARPCjk9EhengMtiSKO9Md/4OAJ/lho7jIOWz4vkOHGv8et1h0= =uRz2 -END PGP SIGNATURE- attachment: martin_raspaud.vcf___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
