It took me a bit to figure out how to do absolute values in RethinkDB, because you can’t use conditionals and mathematical operations that you might normally expect.<\/p>\n
I expect that abs will be added to the language relatively soon, based on the outstanding tickets, but if you need it now, here is how to implement it:<\/p>\n
\n 'aDelta': \n r.branch(\n row('Delta').gt(0), \n row('Delta'), \n row('Delta').mul(0)\n ),\n<\/pre>\nThe following query is more complete if you want to see an example in action – this computes root-mean-square variance as well (unfortunately there does not appear to be a power function in the language as yet, so you can’t do the square root at the end that you’d want)<\/p>\n
\nr.database('performance')\n .table('query_timings)\n .map(function(row) {\n return {\n 'Delta': row('Delta'),\n 'aDelta': \n r.branch(\n row('Delta').gt(0), \n row('Delta'), \n row('Delta').mul(0)\n ),\n 'rmsDelta': row('Delta').mul(row('Delta')),\n 'Count': 1\n }\n })\n .group('Count')\n .reduce(function(left, right) {\n var Delta = left('Delta').add(right('Delta'));\n var aDelta = left('aDelta').add(right('aDelta'));\n var rmsDelta = left('rmsDelta').add(right('rmsDelta'));\n var Count = left('Count').add(right('Count')); \n \n return {\n Delta: Delta,\n Count: Count,\n aDelta: aDelta,\n rmsDelta: rmsDelta,\n Variance: rmsDelta.exp(0.5),\n Avg: Delta.div(Count)\n }\n })\n<\/pre>\n","protected":false},"excerpt":{"rendered":"It took me a bit to figure out how to do absolute values in RethinkDB, because you can’t use conditionals and mathematical operations that you might normally expect. I expect that abs will be added to the language relatively soon, based on the outstanding tickets, but if you need it now, here is how to … <\/p>\n