D3 import .csv to 2Darray & opacity change when hover - arrays

Question

I'm currently writing a visualization via D3 and I hope you can help me out.
To get an idea of what I'm making you can view this link: https://dl.dropboxusercontent.com/u/56480311/Data-visualization/index.html
I'm facing two problems: the first is that I can't seem to place .csv data in a 2D array. I found multiplie tutorials about placing it in a normal array but the only solution I came up with if your data is in a table, is to use a 2D array. I couldn't find how to do this so what I thought would help:
var lines = []; //define lines as an array
//retrieve data from .csv file
d3.csv("https://dl.dropboxusercontent.com/u/56480311/Data-visualization/growth-prep.csv", function(data) {
lines = data.map(function(d) {
return d;
});
});
//create 2D array named myArray
var myArray = new Array(10);
for (var i = 0; i < 10; i++) {
myArray[i] = new Array(18);
}
//place each value of .csv file into myArray
for (var j = 0; j < lines.length; j++) {
var values = lines[j].split(";");
for (var k = 0; k < values.length; k++) {
myArray[k][j] = values[k];
}
}
This code doesn't work, however. Console keeps saying that the arrays are undefined and they're empty.
A second problem I'm facing is in visualizing the data. I sum three values that are next to each other (so for example dataset[0][0] + dataset[0][1] + dataset[0][2]). I draw this value as the width of a rectangle. On top of that, I want to draw three different rectangles each with the value of one of three. So in this case there is one rectangle consisting of dataset[0][0] + dataset[0][1] + dataset[0][2] and on top there is a rectangle showing data dataset[0][0], one showing data dataset[0][1] and a third showing data dataset[0][2]. I want the three smaller ones only to appear once the mouse hovers over the 'sum' / parent rectangle.
If you view the link you can see what I mean. Everything is already there, only the three smaller rectangles have opacity 0 so you don't see them yet (but you can find them via inspect elements).
I figured I could do this by setting the opacity of the three rectangles to 0 and to 1 once the mouse hovers. The best solution to me would be to place the three rectangles into one kind of div. Once the mouse hovers over it, its opacity is 1. Only I can't figure out how to easily give different class names without having to do it by hand for each rectangle separately. Does anyone know how to do this or else have a better solution to change the opacity of all three rectangles once the mouse hovers over the 'bigger' rectangle?
This is the code:
var dataset = [[6,6,3,3,3,0,6,6,0,12,6,6,0,0,18,6,3,3],[3,0,0,6,3,0,3,3,0,9,3,0,0,0,18,6,6,6],[3,0,3,6,3,3,6,0,3,9,6,3,0,0,15,6,6,6],[6,6,3,3,0,3,6,6,6,12,6,6,0,0,18,6,6,3],[6,6,0,6,0,0,6,6,6,12,6,6,0,0,24,6,6,0],[3,6,3,6,3,3,6,6,3,3,0,0,0,0,15,3,9,6],[3,3,0,3,0,3,3,3,3,9,3,0,0,0,15,6,3,9],[0,0,0,3,0,6,6,3,3,3,0,3,0,0,24,6,12,6],[6,6,3,6,0,0,9,9,6,12,6,6,0,0,15,3,3,3],[6,6,0,6,3,0,6,6,0,9,6,3,0,0,9,3,6,0]];
var h = 800;
var w = 800;
//create svg of 800x800px
var svg = d3.select("body")
.append("svg")
.attr("width", w)
.attr("height", h);
var xPos = 150;
for (var k = 0; k < 10; k++) { //loop through lines of array
var yPos = 40 + k*80;
for (var j = 0; j < 18; j++) { //loop through rows of array
var count = j + 1;
//assign data of three boxes to value1/value2/value3 with which we will later on draw three separate rectangles to visualize the data
if (count == 1 || count == 4 || count == 7 || count == 10 || count == 13 || count == 16) {
var value1 = dataset[k][j];
}
if (count == 2 || count == 5 || count == 8 || count == 11 || count == 14 || count == 17) {
var value2 = dataset[k][j];
}
if (count == 3 || count == 6 || count == 9 || count == 12 || count == 15 || count == 18) {
var value3 = dataset[k][j];
}
if (count % 3 ==0) {
var sum = dataset[k][j] + dataset[k][j-1] + dataset[k][j-2]; //count the three values to also draw one bigger rectangle of their sum
var rectangle = svg.append("rect")
.attr("x", xPos)
.attr("y", yPos)
.attr("width", sum*5)
.attr("height", 20)
.attr("fill", function(d) {
if (count == 3) {
return "LightSeaGreen";
}
else if (count == 6) {
return "MediumSeaGreen";
}
else if (count == 9) {
return "MediumSpringGreen";
}
else if (count == 12) {
return "LimeGreen";
}
else if (count == 15) {
return "ForestGreen"
}
else if (count == 18) {
return "GreenYellow"
}
});
for (var l = 0; l < 3; l++) { //draw three 'sub' rectangles on top of the one 'sum' rectangle. they should appear when the mouse hovers over their 'sum' rectangle
var rectangle2 = svg.append("rect")
.attr("class", "sqr")
.attr("x", function() {
if (l == 0) {
return xPos;
} else if (l == 1) {
return xPos + value1*5;
} else if (l == 2) {
return xPos + (value1+value2)*5;
}
})
.attr("y", yPos)
.attr("width", function() {
if (l == 0) {
return value1*5;
} else if (l == 1) {
return value2*5;
} else if (l == 2) {
return value3*5;
}
})
.attr("height", 20)
.attr("fill", function() {
if (l == 0) {
return "SteelBlue";
} else if (l == 1) {
return "aquamarine";
} else if (l == 2) {
return "SkyBlue";
}
})
.attr("opacity", 0); //in first instance the rectangles are not visible. Opacity should turn to 1 when the mouse hovers over their according div
}
if (sum > 0) {
xPos = xPos + sum*5 + 5;
}
}
}
xPos = 150;
}