pip install pydensecrf

環境為python3.7.7+Ubuntu16.04，部分報錯資訊如下

ERROR: Command errored out with exit status 1:
pydensecrf/eigen.cpp: In function ‘void __Pyx__ExceptionSave(PyThreadState*, PyObject**, PyObject**, PyObject**)’:
pydensecrf/eigen.cpp:17032:21: error: ‘PyThreadState {aka struct _ts}’ has no member named ‘exc_type’
 
*type = tstate->exc_type;
^
{aka struct _ts}’ has no member named ‘exc_value’te
*value = tstate->exc_value;
^
pydensecrf/eigen.cpp:17034:19: error: ‘PyThreadState {aka struct _ts}’ has no member named ‘exc_traceback’
*tb = tstate->exc_traceback;
^
pydensecrf/eigen.cpp: In function ‘void __Pyx__ExceptionReset(PyThreadState*, PyObject*, PyObject*, PyObject*)’:
pydensecrf
 
/eigen.cpp:17041:24: error: ‘PyThreadState {aka struct _ts}’ has no member named ‘exc_type’
tmp_type = tstate->exc_type;
^
pydensecrf/eigen.cpp:17042:25: error: ‘PyThreadState {aka struct _ts}’ has no member named ‘exc_value’
tmp_value = tstate->exc_value;
^
pydensecrf/eigen.cpp:17043:22: error: ‘PyThreadState {aka struct _ts}’ has no member named ‘exc_traceback’
tmp_tb 
 
= tstate->exc_traceback;
^
pydensecrf/eigen.cpp:17044:13: error: ‘PyThreadState {aka struct _ts}’ has no member named ‘exc_type’
tstate->exc_type = type;
^
pydensecrf/eigen.cpp:17045:13: error: ‘PyThreadState {aka struct _ts}’ has no member named ‘exc_value’
tstate->exc_value = value;
^
pydensecrf/eigen.cpp:17046:13: error: ‘PyThreadState {aka struct _ts}’ has no member named ‘exc_traceback’
tstate->exc_traceback = tb;
^
pydensecrf/eigen.cpp: In function ‘int __Pyx__GetException(PyThreadState*, PyObject**, PyObject**, PyObject**)’:
pydensecrf/eigen.cpp:17101:24: error: ‘PyThreadState {aka struct _ts}’ has no member named ‘exc_type’
tmp_type = tstate->exc_type;
^
pydensecrf/eigen.cpp:17102:25: error: ‘PyThreadState {aka struct _ts}’ has no member named ‘exc_value’
tmp_value = tstate->exc_value;
^
pydensecrf/eigen.cpp:17103:22: error: ‘PyThreadState {aka struct _ts}’ has no member named ‘exc_traceback’
tmp_tb = tstate->exc_traceback;
^
pydensecrf/eigen.cpp:17104:13: error: ‘PyThreadState {aka struct _ts}’ has no member named ‘exc_type’
tstate->exc_type = local_type;
^
pydensecrf/eigen.cpp:17105:13: error: ‘PyThreadState {aka struct _ts}’ has no member named ‘exc_value’
tstate->exc_value = local_value;
^
pydensecrf/eigen.cpp:17106:13: error: ‘PyThreadState {aka struct _ts}’ has no member named ‘exc_traceback’
tstate->exc_traceback = local_tb;
^
pydensecrf/eigen.cpp: In function ‘void __Pyx__ExceptionSwap(PyThreadState*, PyObject**, PyObject**, PyObject**)’:
pydensecrf/eigen.cpp:17128:24: error: ‘PyThreadState {aka struct _ts}’ has no member named ‘exc_type’
tmp_type = tstate->exc_type;
^
pydensecrf/eigen.cpp:17129:25: error: ‘PyThreadState {aka struct _ts}’ has no member named ‘exc_value’
tmp_value = tstate->exc_value;
^
pydensecrf/eigen.cpp:17130:22: error: ‘PyThreadState {aka struct _ts}’ has no member named ‘exc_traceback’
tmp_tb = tstate->exc_traceback;
^
pydensecrf/eigen.cpp:17131:13: error: ‘PyThreadState {aka struct _ts}’ has no member named ‘exc_type’
tstate->exc_type = *type;
^
pydensecrf/eigen.cpp:17132:13: error: ‘PyThreadState {aka struct _ts}’ has no member named ‘exc_value’
tstate->exc_value = *value;
^
pydensecrf/eigen.cpp:17133:13: error: ‘PyThreadState {aka struct _ts}’ has no member named ‘exc_traceback’
tstate->exc_traceback = *tb;
^

解決方案：

1. 網上查詢到的方案多為：該報錯是因為未安裝cython，因此使用pip install cython（本次報錯實際已經安裝cython，因此繼續糾錯）
2. 據說用conda安裝不會報錯，即：conda install -c conda-forge pydensecrf（本次環境中未安裝conda，不考慮此方案）
3. 使用git直接安裝最近版本，最終未報錯，即：pip install git+https://github.com/lucasb-eyer/pydensecrf.git