[summer 2020] Optimized TF 2.2 r-tensorflow R4.0.0 Ubuntu 18.04

optimized-tf-r-ubuntu

R package tensorflow use the conda envirnment "r-tensorflow". hence I have to install my compiled version of tf within that environment

1. update system and python
```
sudo apt-get update
sudo apt-get upgrade
```

2. install and update conda, and anaconda
```
conda update conda
conda update conda-build

conda deactivate
conda update --all
# conda remove --name r-tensorflow --all
```


3. install bazel
# adapted from https://gist.github.com/Brainiarc7/6d6c3f23ea057775b72c52817759b25c
```
# one time setup
$ sudo apt-get install software-properties-common swig
$ sudo apt install curl
$ curl https://bazel.build/bazel-release.pub.gpg | sudo apt-key add -
$ echo "deb [arch=amd64] https://storage.googleapis.com/bazel-apt stable jdk1.8" | sudo tee /etc/apt/sources.list.d/bazel.list

$ sudo apt update && sudo apt install bazel
# currently I have bezel 3.1 which is ok :
# as https://github.com/tensorflow/tensorflow/blob/master/configure.py
# states 
# _TF_MIN_BAZEL_VERSION = '2.0.0'
# _TF_MAX_BAZEL_VERSION = '3.99.0'
```

4. I need also jdk # https://thishosting.rocks/install-java-ubuntu/
```
java --version # do I need it?? probably not (at least version 8, now it is 11)
## for Ubuntu 18.04 it is 11:
sudo apt update && apt install sudo apt install openjdk-11-jdk
```

5. install/check other needed packages
```
sudo apt-get update && sudo apt-get install -y python3-numpy python3-dev python3-pip python3-wheel
```


6. enter the environment
```
# conda create -n r-tensorflow python=3 # if already created deleate it!
conda activate r-tensorflow
```


7. install numpy and other dependencies
```
 conda install six numpy wheel setuptools mock 'future>=0.17.1'
 pip install -U keras_applications --no-deps
 pip install -U keras_preprocessing --no-deps
```


8. download tensorflow
```
git clone https://github.com/tensorflow/tensorflow
cd tensorflow/
git checkout r2.2 # r2.2 is actually the latest branch for tf
```


9. install it (remember...last time ~11 hours!!)
```
sudo apt install bazel-2.0.0
yes "" | ./configure

# the following command takes long time
bazel build --config=opt tensorflow/tools/pip_package:build_pip_package

mkdir build_pkg
bazel-bin/tensorflow/tools/pip_package/build_pip_package `pwd`/build_pkg
cd build_pkg
pip install --upgrade tensorflow-*
```

10. check no warnings when it runs!
# run a simple TF model

11. exit from teh environment
```
conda deactivate
```
12. enjoy.