cartopy 0.18 has problems when installing numpy at the same time, change to...

cartopy 0.18 has problems when installing numpy at the same time, change to xargs installation (line by line pip install)

.gitlab-ci.yml

@@ -43,7 +43,7 @@ tests (from scratch):
   script:
     - zypper --non-interactive install binutils libproj-devel gdal-devel
     - zypper --non-interactive install proj geos-devel
-    - pip install -r requirements.txt
+    - cat requirements.txt | xargs -L 1 pip install
     - chmod +x ./CI/run_pytest.sh
     - ./CI/run_pytest.sh
   after_script:
@@ -72,7 +72,7 @@ tests (on GPU):
     - chmod +x ./CI/update_badge.sh
     - ./CI/update_badge.sh > /dev/null
   script:
-    - pip install -r requirements_gpu.txt
+    - cat requirements_gpu.txt | xargs -L 1 pip install
     - chmod +x ./CI/run_pytest.sh
     - ./CI/run_pytest.sh
   after_script:
@@ -96,7 +96,7 @@ tests:
     - chmod +x ./CI/update_badge.sh
     - ./CI/update_badge.sh > /dev/null
   script:
-    - pip install -r requirements.txt
+    - cat requirements.txt | xargs -L 1 pip install
     - chmod +x ./CI/run_pytest.sh
     - ./CI/run_pytest.sh
   after_script:
@@ -120,7 +120,7 @@ coverage:
     - chmod +x ./CI/update_badge.sh
     - ./CI/update_badge.sh > /dev/null
   script:
-    - pip install -r requirements.txt
+    - cat requirements.txt | xargs -L 1 pip install
     - chmod +x ./CI/run_pytest_coverage.sh
     - ./CI/run_pytest_coverage.sh
   after_script:
@@ -142,8 +142,8 @@ sphinx docs:
     - chmod +x ./CI/update_badge.sh
     - ./CI/update_badge.sh > /dev/null
   script:
-    - pip install -r requirements.txt
-    - pip install -r docs/requirements_docs.txt
+    - cat requirements.txt | xargs -L 1 pip install
+    - cat docs/requirements.txt | xargs -L 1 pip install
     - chmod +x ./CI/create_documentation.sh
     - ./CI/create_documentation.sh
   after_script:

README.md

@@ -21,7 +21,10 @@ HPC systems, see [here](#special-instructions-for-installation-on-jülich-hpc-sy
 * (geo) Install **proj** and **GEOS** on your machine using the console.
 * Install the **python3.6 develop** libraries.
 * Install all **requirements** from [`requirements.txt`](https://gitlab.version.fz-juelich.de/toar/mlair/-/blob/master/requirements.txt)
-  preferably in a virtual environment
+  preferably in a virtual environment. You can use `pip install -r requirements.txt` to install all requirements at 
+  once. Note, we recently updated the version of Cartopy and there seems to be an ongoing 
+  [issue](https://github.com/SciTools/cartopy/issues/1552) when installing numpy and Cartopy at the same time. If you
+  run into trouble, you could use ` cat requirements.txt | xargs -L 1 pip install` instead.
 * Installation of **MLAir**:
     * Either clone MLAir from the [gitlab repository](https://gitlab.version.fz-juelich.de/toar/mlair.git) 
       and use it without installation (beside the requirements)