fixed bug in CPU_ONLY compilation

Author: benja263

README.md

@@ -28,13 +28,7 @@ xcode command line tools should be installed installed
 ### Installation
 ```
 pip install gbrl
-```
-To install a cpu only version please run
-```
-CPU_ONLY=1 pip install gbrl
-```
-
-For GPU support GBRL looks for `CUDA_PATH` or `CUDA_HOME` environment variables. Unless found, GBRL will automatically compile only for CPU.
+``` 
 
 Verify that GPU is visible by running
 ```
@@ -43,6 +37,8 @@ import gbrl
 gbrl.cuda_available()
 ```
 
+GBRL can be compiled and installed with a CPU version only even on CUDA capable machines by setting `CPU_ONLY=1` as an environment variable. 
+
 *OPTIONAL*  
 For tree visualization make sure graphviz is installed before compilation. 
 

docs/quickstart.rst

@@ -7,8 +7,4 @@ Install GBRL via pip:
    
    pip install gbrl
 
-CPU only version is installed with the following command:
-
-.. code-block:: console
-
-   CPU_ONLY=1 pip install gbrl
+GBRL can be compiled and installed with a CPU version only even on CUDA capable machines by setting `CPU_ONLY=1` as an environment variable.

setup.py

@@ -59,7 +59,7 @@ def build_extension(self, ext):
             cmake_args.append('-DCMAKE_VERBOSE_MAKEFILE:BOOL=ON')
             build_args.append('--verbose')
 
-        if ('CPU_ONLY' not in os.environ and platform.system() != 'Darwin') or ('CPU_ONLY' in os.environ and os.environ['CPU_ONLY'] == '1'):
+        if ('CPU_ONLY' not in os.environ and platform.system() != 'Darwin') or ('CPU_ONLY' in os.environ and os.environ['CPU_ONLY'] != '1'):
             cmake_args.append('-DUSE_CUDA=ON')
 
         build_temp = self.build_temp