Installing pytorch/torchvision on centos7

The installation command shown on didn’t quite work for me on centos7. Instead of using the anaconda installer provided on pytorch, I just used the yum-provided conda:

yum install conda

However when i went to run the command as specified I got the following error:

~$ conda install pytorch torchvision cudatoolkit=10.0 -c pytorch

NoBaseEnvironmentError: This conda installation has no default base environment. Use
'conda create' to create new environments and 'conda activate' to
activate environments.

It seems the problem is that pytorch is assuming you’ve set up a working conda environment – which i had not. You can work around this by simply naming the environment (I suppose you could also have made a base environemnt, but I decided to save that adventure for another day). The following did work for me:

conda create -n pytorch pytorch torchvision matplotlib cudatoolkit=10.0 -c pytorch

Note I also added matplotlib as I was following pytorch examples that requires it. Also, I found I could run any pytorch example by directly referencing the conda environment, instead of activating it and then running the script, as follows:


Installing OpenCV 4.1.1 on Raspberry Pi 4

Recently I purchased a raspberry pi 4 to see how it performs basic computer vision tasks. I largely followed this guide on building opencv

However, in the guide there are several missing dependencies on a fresh version of raspbian buster. There are also some apparent errors in the CMakeLists.txt file which other users already discovered. After patching these fixes and adding the needed missing dependencies, I now have opencv running on my pi. Here’s my complete script below.

IMPORTANT: You must READ the script, don’t just run it! For example, you should check the version of python you have at the time you run this script. When I ran it i was at python 3.7. Also, feel free to bump to a later version (or master) of opencv.

Oh, also during the numpy step it hung and i was too lazy to look into it. It didn’t seem to affect my ability to use opencv – so i didn’t go back and dig. My bad.



sudo apt-get -y purge wolfram-engine
sudo apt-get -y purge libreoffice*
sudo apt-get -y clean
sudo apt-get -y autoremove

mkdir -p $opencvDirRoot
cd $opencvDirRoot

# Clean build directories
rm -rf opencv/build
rm -rf opencv_contrib/build

# Create directory for installation
rm -fr installation
mkdir -p installation
mkdir installation/OpenCV-"$cvVersion"

sudo apt -y update
sudo apt -y upgrade
sudo apt-get -y remove x264 libx264-dev
## Install dependencies
sudo apt-get install libblas-dev liblapack-dev
sudo apt-get install libeigen3-dev
sudo apt-get -y install qtbase5-dev qtdeclarative5-dev
sudo apt-get -y install build-essential checkinstall cmake pkg-config yasm
sudo apt-get -y install git gfortran
sudo apt-get -y install libjpeg8-dev libjasper-dev libpng12-dev

sudo apt-get -y install libtiff5-dev
sudo apt-get -y install libtiff-dev

sudo apt-get -y install libavcodec-dev libavformat-dev libswscale-dev libdc1394-22-dev
sudo apt-get -y install libxine2-dev libv4l-dev
cd /usr/include/linux
sudo ln -s -f ../libv4l1-videodev.h videodev.h
cd $opencvDirRoot

sudo apt-get -y install libgstreamer0.10-dev libgstreamer-plugins-base0.10-dev
sudo apt-get -y install libgtk2.0-dev libtbb-dev qt5-default
sudo apt-get -y install libatlas-base-dev
sudo apt-get -y install libmp3lame-dev libtheora-dev
sudo apt-get -y install libvorbis-dev libxvidcore-dev libx264-dev
sudo apt-get -y install libopencore-amrnb-dev libopencore-amrwb-dev
sudo apt-get -y install libavresample-dev
sudo apt-get -y install x264 v4l-utils
sudo apt-get -y install libmesa-dev
sudo apt-get -y install freeglut3-dev

# Optional dependencies
sudo apt-get -y install libprotobuf-dev protobuf-compiler
sudo apt-get -y install libgoogle-glog-dev libgflags-dev
sudo apt-get -y install libgphoto2-dev libeigen3-dev libhdf5-dev doxygen

sudo apt-get -y install python3-dev python3-pip
sudo -H pip3 install -U pip numpy
sudo apt-get -y install python3-testresources

cd $opencvDirRoot
# Install virtual environment
python3 -m venv OpenCV-"$cvVersion"-py3
echo "# Virtual Environment Wrapper" >> ~/.bashrc
echo "alias workoncv-$cvVersion=\"source $opencvDirRoot/OpenCV-$cvVersion-py3/bin/activate\"" >> ~/.bashrc
source "$opencvDirRoot"/OpenCV-"$cvVersion"-py3/bin/activate

############ For Python 3 ############
# now install python libraries within this virtual environment
sudo sed -i 's/CONF_SWAPSIZE=100/CONF_SWAPSIZE=1024/g' /etc/dphys-swapfile
sudo /etc/init.d/dphys-swapfile stop
sudo /etc/init.d/dphys-swapfile start
pip install numpy dlib
# quit virtual environment

git clone
cd opencv
git checkout $cvVersion
cd ..

git clone
cd opencv_contrib
git checkout $cvVersion
cd ..

cd opencv
mkdir build
cd build

# Eigen/Core to eigen3/Eigen/Core
sed -i s,Eigen/Core,eigen3/Eigen/Core/g ../modules/core/include/opencv2/core/private.hpp

# Add these to  opencv/samples/cpp/CMakeLists.txt 
find_package(OpenGL REQUIRED)
find_package(GLUT REQUIRED)

            -D CMAKE_INSTALL_PREFIX=$opencvDirRoot/installation/OpenCV-"$cvVersion" \
            -D INSTALL_C_EXAMPLES=ON \
            -D WITH_TBB=ON \
            -D WITH_V4L=ON \
            -D OPENCV_PYTHON3_INSTALL_PATH=$opencvDirRoot/OpenCV-$cvVersion-py3/lib/python$pythonVersion/site-packages \
        -D WITH_QT=ON \
        -D WITH_OPENGL=ON \
        -D OPENCV_EXTRA_MODULES_PATH=../../opencv_contrib/modules \

make -j$(nproc)
make install

sudo sed -i 's/CONF_SWAPSIZE=1024/CONF_SWAPSIZE=100/g' /etc/dphys-swapfile
sudo /etc/init.d/dphys-swapfile stop
sudo /etc/init.d/dphys-swapfile start

echo "sudo modprobe bcm2835-v4l2" >> ~/.profile