That’s the key!
/.
Suppose we have a two-row table of account numbers and costs Table 1004 1006 1004 1005 1005 1006 1006 1001 1002 1002 102.41 90.89 88.93 103.22 76.5 97.84 98.1 99.83 78.76 75.47 The key adverb (/.) permits applying a function by keys. To summarize (+/) the amounts in the bottom row by the account number keys (/.) in the top row, using the insert adverb (/) to provide the left and right arguments, write (SumAmounts=.+//./) Table 191.34 286.83 179.72 99.83 154.23 The set of account numbers, in the order in which they appear in the top row ({.), and the counts by account, using nub (~.) laminated (,:) on count by key (#/.~) on the top row ({.): (AccountsCounts=.(~. ,: #/.~)@{.) Table 1004 1006 1005 1001 1002 2 3 2 1 2 Display the information in a transposed (|:) format, with the rows sorted (/:~) by account, and a verb for the finished report Report=.Form@(AccountsCounts,SumAmounts) Report Table 1001 1 99.83 1002 2 154.23 1004 2 191.34 1005 2 179.72 1006 3 286.83 |