> definitions of data.frames vs. matrix vs vectors. I have read many R. > tutorials, and looked over ump-teen 'cheat' sheets and have found that. > no one has articulated a really good definition of the differences. > between 'data.frames', 'matrix', and 'arrays' and even 'factors'.
Medical Definition of Tumor Our Tumor (Grade) Main Article provides a comprehensive look at the who, what, when and how of Tumor (Grade) Tumor: An abnormal mass of tissue. Tumors are a classic sign of inflammation, and can be benign or malignant (cancerous). There are dozens of different types of tumors. Their names usually reflect the kind of tissue they arise in, and may also tell you something about their shape or how they grow.
Benign tumor. A benign tumor is a mass of cells (tumor) that lacks the ability to invade neighboring tissue or metastasize. These characteristics are required for a tumor to be defined as cancerous and therefore benign tumors are non-cancerous. Also, benign tumors generally have a slower growth rate than malignant tumors and the tumor cells are usually more differentiated (cells have normal features).