Update by to use the latest tree-math.

bin/by.js

@@ -31,17 +31,19 @@ var outvals     = values.map(function(a){return a.length===1?a[0]:a[1];});
 var all = {};
 parseStream(process.stdin)
 .on('jline', function(record){
-        var storepath = inpaths.map(function(path){return getPath(record, [].concat(path));});
+	var recordPath = getPath.bind(null,record);
+        var storepath = inpaths.map(recordPath);
+	var storenode = storepath.reduce(function(d,k){if(d[k]===undefined)d[k]={};return d[k];},all);
         invals.forEach(function(inpath, index){
-            incrementPath(all, storepath.concat(outvals[index]), getPath(record, [].concat(inpath)));
+            incrementPath(storenode, outvals[index], getPath(record, inpath));
         });
 })
 .on('end', function(){
         var maxdepth = inpaths.length;
         var path = [];
-	find(all, function(path, val){
+	find(all,{maxdepth:maxdepth}, function(path, val){
             outpaths.forEach(function(outpath, index){
-                setPath(val, outpath.concat([]), path[index]);
+                setPath(val, outpath, path[index]);
             });
             console.log(JSON.stringify(val));
         }, path, maxdepth);

bin/by.md

@@ -7,8 +7,13 @@ Reduce values to some breakdown.  E.g. if you have a whole lot of records that l
 
 You may want to get the total number of sightings by year.  You can do this with:
 
-    cat data | jline-breakdown year -- sightings
+    cat data | jline-by year -- sightings
 
+This will output one JSON line for each year together with the total number of sightings for that year:
+
+    {"sightings":135,"year":"1982"}
+    {"sightings":172,"year":"1983"}
+    {"sightings":211,"year":"1984"}
 
 ## Command line:
 

bin/foreach.js

@@ -32,7 +32,7 @@ function keyvals(dict, callback){
 
 function setpath(subject,path,value){
 	var c=path.length;
-	path.reduce(function(s,n){return s[n]=--c?(s[n]||{}):value;var after=s[n];},subject);
+	var ans = path.reduce(function(s,n){return s[n]=--c?(s[n]||{}):value;var after=s[n];},subject);
 }
 function getpath(subject,path){
 	return path.reduce(function(s,n){if(s!==undefined)return s[n];},subject);

package.json

@@ -58,7 +58,7 @@
   "dependencies": {
     "docopt": "^0.4.1",
     "split": "^0.3.0",
-    "tree-math": "0.0.3",
+    "tree-math": "0.0.16",
     "ya-csv": "^0.9.4"
   }
 }

test/by.jsonl

@@ -0,0 +1,5 @@
+{"state":"Georgia", "year":1982, "sightings":27, "validatedSightings":19}
+{"state":"New Jersey", "year":1982, "sightings":26, "validatedSightings":17}
+{"state":"Georgia", "year":1982, "sightings":28, "validatedSightings":21}
+{"state":"California", "year":1982, "sightings":25, "validatedSightings":4}
+{"state":"Georgia", "year":1982, "sightings":29, "validatedSightings":1}

test/by.sh

@@ -0,0 +1,9 @@
+
+cd "$(dirname "$0")/.."
+
+set -eux
+
+    ./bin/by.js --help					|| (($? == 2))
+    ./bin/by.js year -- sightings <test/by.jsonl
+
+echo OK