I'm quite puzzled about what to use or install, because there are a plethora of components old and new, and the relationship between them is quite unclear to me.
There is OpenCV, the C++ library that does the heavy lifting.
Then there are various packages that provide Python support, including:
opencv-python - Python packages for OpenCV; also installs OpenCV itself. Available with import cv2.
pyopencv - a very old library.
python-opencv - a Debian package.
libopencv, described in another question here as "only a metapackage", but its purpose remains unclear to me.
Possibly I have missed some...
For a modern Python 3 project, which of these components should be used?
Using import cv
I am trying to use OpenCV with a Django project, that expects to find the library with import cv.
That recommends installing python-opencv. It also mentions pyopencv which seems odd, given how old the latter is.
What package does make a cv module available?
System vs Python packages
It looks like python-opencv is a system-level package that also installs Python modules, whereas opencv-python is a Python package that also installs system-level modules.
Is that correct? In which case, am I right in thinking that one would install both system and Python libraries using one of these but not both?
in opencv3 the old cv or cv2.cv api was removed, to use opencv correctly in python is enough with import cv2.
another package would be opencv-contrib-python
Related
The server that I am using has an older version of python installed, and I am unable to install packages. Is there a workaround to importing python modules? If I can create my own module and append the directory to be able to import the newly created module, then I am assuming that I should be able to do the same for already built packages. I just need to know how I would be able to install what is required for numpy and then import it using a similar method as when creating modules.
I would recommend that you find a machine to install the same version of Python to match your server. Perform the pip install from that stand alone machine. Do some level of testing to make sure that the code with run with that version of Python and everything is happy. Just the other day I found out the hard way that TensorFlow would now work on the latest Python.
The libraries are being installed for me under c:\users\<profilename>\AppData\Local\Programs\Python\Python36\Lib\site-packages So you could then copy that over to the server.
I found this link that is saying the same thing.
https://superuser.com/questions/943980/is-it-possible-to-install-python-packages-without-a-direct-outbound-network-conn
Good Luck with it.
I am creating a requirements.txt file for my Python project. When someone installs my project via pip; I want pip to also download the Tkinter and time Python modules, both of which are modules in the Python Standard Library.
I used the command pip freeze to list all of the currently installed Python packages, but when I scrolled down to the T section, I could not find Tkinter or time in the list. I then tried to install Tkinter via pip using the command pip install Tkinter but got the following error:
Could not find a version that satisfies the requirement Tkinter (from versions: )
No matching distribution found for Tkinter
I also did the same with time and got the same error. (I am running Python 3.6 and Windows 10.)
Is it possible to get pip to install those modules while pip is installing my package, or do I just have to trust that because the user has Python installed they will also have Tkinter and time installed?
All help is welcome and appreciated!
Python's Standard Library is called the Standard Library because it is a standard of Python. In other words, if there is no Standard Library installed, the python environment is not python at all.
The Standard Library is tested and released together with each Python release as part of this release (not as an addition or extension).
So, YES, you can expect these libraries to exist if the user has Python installed. Just by definition.
Regarding the upgrades of the built-in libraries: NO, you cannot do this. Because they are part of the python setup, not of the application environment. Python is very tightly bound to the specific code in those libraries. All python apps & libs expect the same behavior of those libraries, even if they are buggy.
In addition to that, you cannot install a module/package with the same name as one of the python's builtins, because it will create the ambiguity on import, and can confuse/break all other libraries which depend on it (or worse, the system applications if you install it into the system python).
However, in some cases you can find the backports of some of the libraries. Usually, they are backported from py3 to py2. Of course, their name is changed.
As an example, you can look into concurrent.features library, which is a handy builtin in py3.2+, but was absent in py2.7.
UPD: Though, as #JulienPalard hints in the comments, some OS distributions can split this standard library to simplify the binary dependencies: e.g., on Debian, Tkinter will be installable separately as python3-tk.
This makes sense, indeed, from the point of view of the binary OS packaging: it is not worth installing the UI parts of the python library if you have no UI at all and want to save the disk space.
However, you are still unable to install it via pip. Because this package is not packaged and available separately on PyPI. This standard library separation is made by the selected OS distributions and is resolved with the means of that OS distribution only.
pip installs packages from pypi, which does not expose the standard library, which is bundled into Python.
So in theory you should trust your users environment, if they have Python, they should have the whole stadard library.
But some distributions are splitting Python in a few packages for reasons (A minimal Debian already depends on Python, but they don't want Python to pull tk to pull libx11 to pull the life, the universe, and everything).
So in practice some package will be there, and you can trust the distribs for this, like time will always be here. And some package may not be here, like tkinter, in which case you may want to surround the import tkinter by a try to error a nice "Looks like your distribution does not provide tk by default, please install it.".
Be reassured, you won't have to surround every imports by try statements just in case some distribution splitted the stdlib, just tkinter.
I'm new to opencv and using ubuntu 14.04, I'm confused of the difference with opencv, python-opencv, and libopencv, as I have libopencv and python-opencv installed in my system, but I there is no cv interface accessible, so I have to install opencv which is much hard than python-opencv and libopencv.
I would like to add to Andika's answer.
OpenCV is computer vision a library written using highly optimized C/C++ code. It makes use of multiprocessing in the background. It has a collection of a large number of algorithms tested and verifiend by the developers. The best thing about this is it's FREE under the BSD license.
libopencv is only a metapackage. These packages do not contain actual software, they simply depend on other packages to be installed. So libopencv is a metapackage which simply references one or more related packages which are loosely grouped together. It is dedicated for installing OpenCV in Ubuntu and Debian OS.
opencv-python is the OpenCV library available as a wrapper with bindings for python. The link also shows how to install OpenCV in Ubuntu OS.
libopencv is the debian/ubuntu package while python-opencv is the python wrapper and can be accessed using cv2 interface like COLDSPEED mentioned
I am new to Python and I want to install VLFeat on Ubuntu (13.04).
I am using Eclipse 3.8. For Python, I have installed the PyDev extension on Eclipse.
I have installed Numpy, but I don't know how to install VLFeat. I tried to use their website, but I can't get anything for Python. I have downloaded packages, but I don't know how to install them.
The Menpo Project provides a wrapper around VLFeat: it's called cyvlfeat.
To install cyvlfeat, we strongly suggest you use conda:
conda install -c menlo cyvlfeat
If you don't want to use conda, your
mileage will vary. In particular, you must satisfy the
linking/compilation requirements for the package, which include the
vlfeat dynamic library.
In other words, the nice thing about installing with conda is that it will install (and link) VLFeat dependencies as well.
It may not include all functionalities of VLFeat. Current State as of March 2017:
fisher
fisher
generic
set_simd_enabled, get_simd_enabled, cpu_has_avx, cpu_has_sse3, cpu_has_sse2
get_num_cpus,
get_max_threads, set_num_threads, get_thread_limit
hog
hog
kmeans
kmeans
kmeans_quantize
ikmeans, ikmeans_push
hikmeans, hikmeans_push
sift
dsift
sift
Relevant reading
Dev blog by Simmi Mourya. This includes descriptions and usage examples.
More alternatives:
vlfeat-ctypes: minimal VLFeat interface for python
pyvlfeat fork by jchazalon: A high-level Python wrapper around a subset of the VLFeat library [more recently updated than the original]
Note about the IDE
Installing python packages should be independent of the IDE (Eclipse + PyDev, in the OP case), as long as the interpreter and libraries paths are correctly set up.
Note about conda
It is not required to install the Anaconda distribution in order to use conda. The much lighter Miniconda is enough.
Assuming you are getting VLFeat from the Python Package Index, the instructions are
Download distribution, extract it, get to command prompt and type:
$ python setup.py install
I'm running OS X Leopard. I followed this site to install it. Trying to run any demo script, I now get "No module named opencv.cv", which is obviously stopping me from doing any programming. I am running python 2.5.1 (yes, I know it's kind of old).
Why would this be, and how can I solve it?
Thanks
You need to compile openCV unfortunately. It's not that hard to do though at least.
A nice route is to use MacPorts: First, be sure to have py26-numpy installed to have support for basic functions such as cv.fromarray :
sudo port install py26-numpy
Then, opencv will compile (with no problem on my side):
sudo port install opencv +python26
Your link tells to install OpenCV with MacPorts, which currently installs version 2.2.0. The API was changed for 2.2, so that might be the reason opencv.cv doesn't exist (also your link is written for the ancient 1.0). OpenCV changelog explains it:
http://opencv.willowgarage.com/wiki/OpenCV%20Change%20Logs
It isn't clear to me how up-to-date the OpenCV documentation is nowadays but I recommend looking at it:
http://opencv.willowgarage.com/documentation/python/index.html
(Python examples there begin with import cv)