两个对象数组正在合并，但它们没有排序 - D3

Question

I've read this [SO post][1], it has helped, but it looks like it has played around with the data...

I have read in two CSV files that look like this:

word, frequency
random, 462546
stupid, 34652
dumb, 4346

I've merged them, which works. I've sorted them, however, it half works. The sorting function sorts the two array of objects as if they were separate. What I mean by this, is that my two arrays of objects merge together, but it has merged them one after another. Then sorted one array of objects, then sorted the other, without sorting them as one whole array, it's sorting them as two arrays.

A link to my CSV files is here enter link description here

d3.csv("data/ArsenalDictionary.csv", function(error1, Arsenal) {
    d3.csv("data/ChelseaDictionary.csv", function(error2, Chelsea) {

        var selected = d3.merge([Arsenal, Chelsea]);

        selected.sort(function(a, b){ return d3.descending(a[2], b[2]); })

        console.log(selected);

    });
});

Answer 1

Your array selected isn't getting sorted because you are attempting to sort the objects by a non-existent property.

The elements of your array are objects with two properties, "words" and " frequency" (note the leading space in the latter). You are attempting to sort them by a property named 2 , which they don't have.

You would have better luck sorting them by the frequency property:

    selected.sort(function(a, b){ return d3.descending(a[" frequency"], b[" frequency"]); });

Note however that this doesn't entirely do what you expect: the frequencies end up in the order 94, 9, 9, 9, ..., 8, 8, 8, ..., etc. This is because they have been sorted as strings, not as numbers.

To deal with this either convert the values to numbers while sorting (note the extra + signs):

    selected.sort(function(a, b){ return d3.descending(+a[" frequency"], +b[" frequency"]); });

Alternatively, you can convert the frequencies to numbers as part of reading in the files:

function mapRow(row) {
    return { "words": row["words"], " frequency": +row[" frequency"] };
}

d3.csv("ArsenalDictionary.csv", mapRow, function(error1, Arsenal) {
    d3.csv("ChelseaDictionary.csv", mapRow, function(error2, Chelsea) {
        // ...

The former is more convenient but the latter may come in more useful if you want to do other things with the numbers, such as add up two counts if both files use the same word. ( world appears in both files).