来自MSN

Don't trust Excel's COUNTA function to count non-blank cells—here's a better method

In most counting scenarios in Excel, COUNTBLANK reliably counts blank cells, and COUNTA reliably counts populated cells. However, with these functions comes a problematic paradox: an empty string from ...
Miami University

Using and Creating Functions

Although there are many functions in the base package of R, sometimes there may not be a function that does exactly what you want. In this case, R allows users to create their own functions and call ...