From 3c6f3a5338652b9eeaa515658e91948f75bf5b34 Mon Sep 17 00:00:00 2001
From: Matt Huntington <matt.huntington@gmail.com>
Date: Tue, 23 Aug 2016 21:28:00 -0400
Subject: [PATCH] data binding

---
 D3.md | 35 +++++++++++++++++++++++++----------
 1 file changed, 25 insertions(+), 10 deletions(-)

diff --git a/D3.md b/D3.md
index 073a04d..0e3d41d 100644
--- a/D3.md
+++ b/D3.md
@@ -65,16 +65,31 @@ d3.text('path', function(error, data){});
 
 ## Data binding
 
-- make a "ghost call" to all circles, even if there are none already
-	- `d3.selectAll('circle').data(dataArray).enter().append('circle');`
-	- `.data(dataArray)` joins each element in dataArray to an element in the selection
-	- `.enter()` returns the sub section of dataArray that has not been matched with DOM elements
-	- `.append()` - creates a DOM element for each of the remaining dataArray elements
-	- once data has been bound to elements, you can call something like `selection.attr('r', function(d,i){ })` or `selection.style('fill', function(d,i){ })`
-		- callback will be executed for each DOM element
-		- `d` is data for the current element
-		- `i` is the index of that element in the array
-	- `.exit().remove()` examines visual elements that are not bound to data and removes them
+```javascript
+d3.selectAll('circle')//make a "ghost call" to all circles, even if there are none already
+	.data(dataArray) //joins each element in dataArray to an element in the selection
+	.enter() //returns the sub section of dataArray that has not been matched with DOM elements
+	.append('circle'); //creates a DOM element for each of the remaining dataArray elements
+```
+
+once data has been bound to elements, you can call something like:
+
+```javascript
+selection.attr('r', function(d,i){ //d is data for the current element, i is the index of that element in the array
+	//callback will be executed for each DOM element
+	//return value is how each value will be set
+	return d.value * 2 //takes value property of d (data), multiplies it by two and sets the radius to that
+})
+```
+
+Can remove elements:
+
+```javascript
+d3.selectAll('circle')//make a "ghost call" to all circles, even if there are none already
+	.data(dataArray) //joins each element in dataArray to an element in the selection
+	.exit() //returns the sub section of DOM elements that has not been matched with dataArray elements
+	.remove(); //removes those elements
+```
 
 ## Linear Scale