[Numpy-discussion] how to count Nan occurrence in a ndarray?

Dear all, I have an ndarray with dimension of 4X62500. is there anyway I can count the number of missing value (NaN)? because I want to know how many observations are missing? Thanks for any idea, Chao -- *********************************************************************************** Chao YUE Laboratoire des Sciences du Climat et de l'Environnement (LSCE-IPSL) UMR 1572 CEA-CNRS-UVSQ Batiment 712 - Pe 119 91191 GIF Sur YVETTE Cedex Tel: (33) 01 69 08 29 02; Fax:01.69.08.77.16 ************************************************************************************