字符串切分
split-string
下面是个例子，用来将一行csv数据用,分隔开成list
$ (split-string "02180376709,4216,4216,0,0.0,221.333333333,597,66,0,0,100000000,22.5631067961,86,1,0,0,100000000,0,3966,0.940702087287,3814,0.904648956357,31.2068694284,1078,1,4,0.000948766603416,260.285714286,1078,7,3564,0.845351043643,34.7701785265,738,1,0,0.0,0,0.0,0,0,1000000000000000,648,0.153700189753,5.87671232877,10,1" ",")
("02180376709" "4216" "4216" "0" "0.0" "221.333333333" "597" "66" "0" "0" "100000000" "22.5631067961" "86" "1" "0" "0" "100000000" "0" "3966" "0.940702087287" "3814" "0.904648956357" "31.2068694284" "1078" "1" "4" "0.000948766603416" "260.285714286" "1078" "7" "3564" "0.845351043643" "34.7701785265" "738" "1" "0" "0.0" "0" "0.0" "0" "0" "1000000000000000" "648" "0.153700189753" "5.87671232877" "10" "1")将光标停留在split-string函数上，按下C-h f，可以看到详细信息。
这样再加上(length)函数，就可以轻松知道csv有多少列了。
$ (length (split-string "..." ","))
47