Swap the first two characters of the content of column 1 '(concat (substring $1 1 2) (substring $1 0 1) (substring $1 2)) Add columns 1 and 2, equivalent to Calc's $1+$2 '(+ $1 $2);N Compute the sum of columns 1-4, like Calc's vsum($1..$4) '(apply '+ '($1..$4));N
![HPatches A benchmark and evaluation of handcrafted and learned local descriptors——2017.04[圖]](data:image/gif;base64,R0lGODlhAQABAIAAAP///wAAACwAAAAAAQABAAACAkQBADs=)