# PyTorch C++ API Ubuntu Installation Guide
The best way to get a clean installation of [PyTorch](https://pytorch.org/), is to install the pre-compiled binaries from the [Anaconda](https://www.anaconda.com/) distribution. Therefore, we need to setup Anaconda first.
## Step 1: Install Anaconda
* Go to the [download section](https://www.anaconda.com/distribution/) and download your desired Anaconda version for Linux
* Run the downloaded shell script and follow the install instruction, do
```shell
cd ~/Downloads
sh Anaconda3-2018.12-Linux-x86_64.sh # actual name depends on your download
```
## Step 2: Setup an Environment
* To keep things clean, now setup an environment for Anaconda, do
```
conda create --name py37_torch python=3.7 # you can choose the name of the environment and the python version
```
* Activate the environment
```
conda activate py37_torch
```
## Step 3: Install PyTorch
There are two different ways on how to proceed.
### Install Pre-Compiled Binaries
* Go to [pytorch.org](https://pytorch.org/) and choose your desired settings like so
* Run the proposed command, here
```
conda install pytorch-cpu torchvision-cpu -c pytorch
```
### Install from Source
Sometime you want to compile from source, due to specific dependencies for example. You can look up what to do [here](https://github.com/pytorch/pytorch). The main steps are
* Get dependencies
```
conda install numpy pyyaml mkl mkl-include setuptools cmake cffi typing
```
* In case you want to use CUDA on a GPU, **otherwise you can skip**
```
# Add LAPACK support for the GPU if needed
conda install -c pytorch magma-cuda92 # or [magma-cuda80 | magma-cuda91] depending on your cuda version
```
* Clone PyTorch from GitHub
```
git clone --recursive https://github.com/pytorch/pytorch
cd pytorch
```
* Install PyTorch, **make sure your environment is activated**
```
export CMAKE_PREFIX_PATH=${CONDA_PREFIX:-"$(dirname $(which conda))/../"}
python setup.py install
```
## Step 4: Link against libtorch.so
Great you came this far, now lets see if everything worked well. Here is a minimal example, on how to link against the C++ API of Pytorch