update API install docs (#2929)

.travis.yml

@@ -36,7 +36,7 @@ install:
   - pip install Pillow==6.2.2  # remove this line when torchvision>=0.5
   - pip install torch==${TORCH} torchvision==${TORCHVISION}
   - pip install mmcv-nightly
-  - pip install "git+https://github.com/open-mmlab/cocoapi.git#subdirectory=PythonAPI"
+  - pip install "git+https://github.com/open-mmlab/cocoapi.git#subdirectory=pycocotools"
   - pip install -r requirements.txt
 
 before_script:

configs/lvis/README.md

@@ -11,6 +11,11 @@
 ```
 
 ## Common Setting
+* Please follow [install guide](../../docs/install.md#install-mmdetection) to install open-mmlab forked cocoapi first.
+* Run following scripts to install our forked lvis-api.
+    ```
+    pip install "git+https://github.com/open-mmlab/cocoapi.git#subdirectory=lvis"
+    ```
 * All experiments use oversample strategy [here](../../docs/tutorials/new_dataset.md#class-balanced-dataset) with oversample threshold `1e-3`.
 * The size of LVIS v0.5 is half of COCO, so schedule `2x` in LVIS is roughly the same iterations as `1x` in COCO.
 

docs/install.md

@@ -58,7 +58,7 @@ for better compatibility with our repo.)
 
 ```shell
 pip install -r requirements/build.txt
-pip install "git+https://github.com/open-mmlab/cocoapi.git#subdirectory=PythonAPI"
+pip install "git+https://github.com/open-mmlab/cocoapi.git#subdirectory=pycocotools"
 pip install -v -e .  # or "python setup.py develop"
 ```
 

mmdet/datasets/lvis.py

@@ -268,8 +268,8 @@ class LVISDataset(CocoDataset):
         try:
             from lvis import LVIS
         except ImportError:
-            raise ImportError('Please follow install.md to '
-                              'install open-mmlab forked cocoapi first.')
+            raise ImportError('Please follow config/lvis/README.md to '
+                              'install open-mmlab forked lvis first.')
         self.coco = LVIS(ann_file)
         assert not self.custom_classes, 'LVIS custom classes is not supported'
         self.cat_ids = self.coco.get_cat_ids()
@@ -310,8 +310,8 @@ class LVISDataset(CocoDataset):
         try:
             from lvis import LVISResults, LVISEval
         except ImportError:
-            raise ImportError('Please follow install.md to '
-                              'install open-mmlab forked cocoapi first.')
+            raise ImportError('Please follow config/lvis/README.md to '
+                              'install open-mmlab forked lvis first.')
         assert isinstance(results, list), 'results must be a list'
         assert len(results) == len(self), (
             'The length of results is not equal to the dataset len: {} != {}'.