我正在关注此示例：http://bl.ocks.org/mbostock/1153292
我有一排排的JSON数据，如下所示：
{"source":"Michael Scott","target":"Jim Halpert","type":"pro"},
{"source":"Jim Halpert","target":"Dwight Schrute","type":"pro"}
呈现此数据的当前代码如下所示：
var links = [
{"source":"Michael Scott","target":"Jim Halpert","type":"pro"},
{"source":"Jim Halpert","target":"Dwight Schrute","type":"pro"}
];
var nodes = {};
links.forEach(function(link) {
link.source = nodes[link.source] || (nodes[link.source] = {name: link.source});
link.target = nodes[link.target] || (nodes[link.target] = {name: link.target});
});
var width = 2000,
height = 1000;
var force = d3.layout.force()
.nodes(d3.values(nodes))
.links(links)
.size([width, height])
.linkDistance(60)
.charge(-300)
.on("tick", tick)
.start();
var svg = d3.select("body").append("svg")
.attr("width", width)
.attr("height", height);
svg.append("defs").selectAll("marker")
.data(["pro"])
.enter().append("marker")
.attr("id", function(d) { return d; })
.attr("viewBox", "0 -5 10 10")
.attr("refX", 15)
.attr("refY", -1.5)
.attr("markerWidth", 6)
.attr("markerHeight", 6)
.attr("orient", "auto")
.append("path")
.attr("d", "M0,-5L10,0L0,5");
var path = svg.append("g").selectAll("path")
.data(force.links())
.enter().append("path")
.attr("class", function(d) { return "link " + d.type; })
.attr("marker-end", function(d) { return "url(#" + d.type + ")"; });
var circle = svg.append("g").selectAll("circle")
.data(force.nodes())
.enter().append("circle")
.attr("r", 6)
.call(force.drag);
var text = svg.append("g").selectAll("text")
.data(force.nodes())
.enter().append("text")
.attr("x", 8)
.attr("y", ".31em")
.text(function(d) { return d.name; });
function tick() {
path.attr("d", linkArc);
circle.attr("transform", transform);
text.attr("transform", transform);
}
function linkArc(d) {
var dx = d.target.x - d.source.x,
dy = d.target.y - d.source.y,
dr = Math.sqrt(dx * dx + dy * dy);
return "M" + d.source.x + "," + d.source.y + "A" + dr + "," + dr + " 0 0,1 " + d.target.x + "," + d.target.y;
}
function transform(d) {
return "translate(" + d.x + "," + d.y + ")";
}
</script>
如何从外部data.json文件调用数据？我已经查看了所有其他相关的SO问题和其他D3示例，但我还没有能够得到任何工作。
我已尝试过（然后将所有对links的引用更改为data）：
d3.json("data.json", function(error, data) {
});
以下是完整代码：
<body>
<script src="//d3js.org/d3.v3.min.js"></script>
<script>
d3.json("data.json", function(error, data) {
});
var nodes = {};
data.forEach(function(link) {
link.source = nodes[link.source] || (nodes[link.source] = {name: link.source});
link.target = nodes[link.target] || (nodes[link.target] = {name: link.target});
});
var width = 2000,
height = 1000;
var force = d3.layout.force()
.nodes(d3.values(nodes))
.data(data)
.size([width, height])
.linkDistance(60)
.charge(-300)
.on("tick", tick)
.start();
var svg = d3.select("body").append("svg")
.attr("width", width)
.attr("height", height);
svg.append("defs").selectAll("marker")
.data(["pro"])
.enter().append("marker")
.attr("id", function(d) { return d; })
.attr("viewBox", "0 -5 10 10")
.attr("refX", 15)
.attr("refY", -1.5)
.attr("markerWidth", 6)
.attr("markerHeight", 6)
.attr("orient", "auto")
.append("path")
.attr("d", "M0,-5L10,0L0,5");
var path = svg.append("g").selectAll("path")
.data(force.data())
.enter().append("path")
.attr("class", function(d) { return "link " + d.type; })
.attr("marker-end", function(d) { return "url(#" + d.type + ")"; });
var circle = svg.append("g").selectAll("circle")
.data(force.nodes())
.enter().append("circle")
.attr("r", 6)
.call(force.drag);
var text = svg.append("g").selectAll("text")
.data(force.nodes())
.enter().append("text")
.attr("x", 8)
.attr("y", ".31em")
.text(function(d) { return d.name; });
function tick() {
path.attr("d", linkArc);
circle.attr("transform", transform);
text.attr("transform", transform);
}
function linkArc(d) {
var dx = d.target.x - d.source.x,
dy = d.target.y - d.source.y,
dr = Math.sqrt(dx * dx + dy * dy);
return "M" + d.source.x + "," + d.source.y + "A" + dr + "," + dr + " 0 0,1 " + d.target.x + "," + d.target.y;
}
function transform(d) {
return "translate(" + d.x + "," + d.y + ")";
}
</script>
这导致此行Uncaught Reference Error: "data" is not defined出现错误data.forEach(function(link) {。 data.json与index.html
我已经尝试了各种其他实现，我从blocks.org上的其他D3示例中选择了。任何和所有的见解将不胜感激。如果有任何我可以做的改进我的问题，请告诉我！
答案 0 :(得分：2)
以下是您的数据的工作示例。您需要做一些事情才能使它与外部json文件一起使用。
请务必在d3.json来电中包含所有代码。
由于我们使用变量链接来保存我们的所有数据，因此您需要将其设置为等于data来自d3.json调用的var data_url = "https://api.myjson.com/bins/10kk91";
d3.json(data_url, function(error, data){
var links = data; //set links equal to data which is returned from d3.json
var nodes = {};
// Compute the distinct nodes from the links.
links.forEach(function(link) {
link.source = nodes[link.source] || (nodes[link.source] = {name: link.source});
link.target = nodes[link.target] || (nodes[link.target] = {name: link.target});
});
var width = 960,
height = 500;
var force = d3.layout.force()
.nodes(d3.values(nodes))
.links(links)
.size([width, height])
.linkDistance(60)
.charge(-300)
.on("tick", tick)
.start();
var svg = d3.select("body").append("svg")
.attr("width", width)
.attr("height", height);
// Per-type markers, as they don't inherit styles.
svg.append("defs").selectAll("marker")
.data(["suit", "licensing", "resolved"])
.enter().append("marker")
.attr("id", function(d) { return d; })
.attr("viewBox", "0 -5 10 10")
.attr("refX", 15)
.attr("refY", -1.5)
.attr("markerWidth", 6)
.attr("markerHeight", 6)
.attr("orient", "auto")
.append("path")
.attr("d", "M0,-5L10,0L0,5");
var path = svg.append("g").selectAll("path")
.data(force.links())
.enter().append("path")
.attr("class", function(d) { return "link " + d.type; })
.attr("marker-end", function(d) { return "url(#" + d.type + ")"; });
var circle = svg.append("g").selectAll("circle")
.data(force.nodes())
.enter().append("circle")
.attr("r", 6)
.call(force.drag);
var text = svg.append("g").selectAll("text")
.data(force.nodes())
.enter().append("text")
.attr("x", 8)
.attr("y", ".31em")
.text(function(d) { return d.name; });
// Use elliptical arc path segments to doubly-encode directionality.
function tick() {
path.attr("d", linkArc);
circle.attr("transform", transform);
text.attr("transform", transform);
}
function linkArc(d) {
var dx = d.target.x - d.source.x,
dy = d.target.y - d.source.y,
dr = Math.sqrt(dx * dx + dy * dy);
return "M" + d.source.x + "," + d.source.y + "A" + dr + "," + dr + " 0 0,1 " + d.target.x + "," + d.target.y;
}
function transform(d) {
return "translate(" + d.x + "," + d.y + ")";
}
}); //end d3.json call。
检查下面的工作代码：
.link {
fill: none;
stroke: #666;
stroke-width: 1.5px;
}
#licensing {
fill: green;
}
.link.licensing {
stroke: green;
}
.link.resolved {
stroke-dasharray: 0,2 1;
}
circle {
fill: #ccc;
stroke: #333;
stroke-width: 1.5px;
}
text {
font: 10px sans-serif;
pointer-events: none;
text-shadow: 0 1px 0 #fff, 1px 0 0 #fff, 0 -1px 0 #fff, -1px 0 0 #fff;
}<script src="https://cdnjs.cloudflare.com/ajax/libs/d3/3.4.11/d3.min.js"></script>/**
* The same timestamp MUST appear in each fragment of a given frame.
* The RTP marker bit MUST be set in the last packet of a frame.
* @param[in] *udp The UDP socket to send the RTP packet over
* @param[in] *Jpeg JPEG encoded image byte buffer
* @param[in] JpegLen The length of the byte buffer
* @param[in] m_SequenceNumber RTP sequence number
* @param[in] m_Timestamp Timestamp of the image in usec
* @param[in] m_offset 3 byte fragmentation offset for fragmented images
* @param[in] marker_bit RTP marker bit
* @param[in] w The width of the JPEG image
* @param[in] h The height of the image
* @param[in] format_code 0 for YUV422 and 1 for YUV421
* @param[in] quality_code The JPEG encoding quality
* @param[in] has_dri_header Whether we have an DRI header or not
*/
static void rtp_packet_send(
struct UdpSocket *udp,
uint8_t *Jpeg, int JpegLen,
uint32_t m_SequenceNumber, uint32_t m_Timestamp,
uint32_t m_offset, uint8_t marker_bit,
int w, int h,
uint8_t format_code, uint8_t quality_code,
uint8_t has_dri_header)
{
#define KRtpHeaderSize 12 // size of the RTP header
#define KJpegHeaderSize 8 // size of the special JPEG payload header
uint8_t RtpBuf[2048];
int RtpPacketSize = JpegLen + KRtpHeaderSize + KJpegHeaderSize;
memset(RtpBuf, 0x00, sizeof(RtpBuf));
/*
The RTP header has the following format:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|V=2|P|X| CC |M| PT | sequence number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| timestamp |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| synchronization source (SSRC) identifier |
+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
| contributing source (CSRC) identifiers |
| .... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* */
m_Timestamp *= 9 / 100; // convert timestamp to units of 1 / 90000 Hz
// Prepare the 12 byte RTP header
RtpBuf[0] = 0x80; // RTP version
RtpBuf[1] = 0x1a + (marker_bit << 7); // JPEG payload (26) and marker bit
RtpBuf[2] = m_SequenceNumber >> 8;
RtpBuf[3] = m_SequenceNumber & 0x0FF; // each packet is counted with a sequence counter
RtpBuf[4] = (m_Timestamp & 0xFF000000) >> 24; // each image gets a timestamp
RtpBuf[5] = (m_Timestamp & 0x00FF0000) >> 16;
RtpBuf[6] = (m_Timestamp & 0x0000FF00) >> 8;
RtpBuf[7] = (m_Timestamp & 0x000000FF);
RtpBuf[8] = 0x13; // 4 byte SSRC (sychronization source identifier)
RtpBuf[9] = 0xf9; // we just an arbitrary number here to keep it simple
RtpBuf[10] = 0x7e;
RtpBuf[11] = 0x67;
/* JPEG header", are as follows:
*
* http://tools.ietf.org/html/rfc2435
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type-specific | Fragment Offset |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Q | Width | Height |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
*/
// Prepare the 8 byte payload JPEG header
RtpBuf[12] = 0x00; // type specific
RtpBuf[13] = (m_offset & 0x00FF0000) >> 16; // 3 byte fragmentation offset for fragmented images
RtpBuf[14] = (m_offset & 0x0000FF00) >> 8;
RtpBuf[15] = (m_offset & 0x000000FF);
RtpBuf[16] = 0x00; // type: 0 422 or 1 421
RtpBuf[17] = 60; // quality scale factor
RtpBuf[16] = format_code; // type: 0 422 or 1 421
if (has_dri_header) {
RtpBuf[16] |= 0x40; // DRI flag
}
RtpBuf[17] = quality_code; // quality scale factor
RtpBuf[18] = w / 8; // width / 8 -> 48 pixel
RtpBuf[19] = h / 8; // height / 8 -> 32 pixel
// append the JPEG scan data to the RTP buffer
memcpy(&RtpBuf[20], Jpeg, JpegLen);
//udp_socket_send_dontwait(udp, RtpBuf, RtpPacketSize); // uncomment after done testing reconstruct rtp packet
};
struct JPEGDepay{
int width;
int height;
int framerate;
int framerate_denom;
bool discontl;
};