Working at WallSt I’ve delt with numerous data providers for our financial information. Data feeds are not cheap especially when you have to deal with individual exchange fees. Often times when selecting a provider you are limited by their charts and graphs. You can usually get ticker information in XML, but graphical data is usually restricted to modules or API calls for an image.
One solution is to obtain a historical feed and develop a charting system, but this can be expensive and time consuming. So how can we do this cost effectively and quickly?
Thank you Yahoo. Yahoo provides historical quotes in spreadsheet (CSV – comma separated values) format which can be easily parsed. I have no idea how they can provide this freely. But I won’t question it 
. Looking at this service, I see that it has changed many times and there are / has been various methods for obtaining their CSV data. So that’s a word for caution should anything change in the future.
Step 1. How to obtain historical quotes:
You can get the data by using the URL below.
http://ichart.finance.yahoo.com/table.csv?s=YHOO
This will provide you with all the EOD price of a company since its IPO. The method above uses the CSV output on a webpage. Yahoo has other URLs that output a downloadable files. Those work also and can be parsed just as easily.
If you want to be able to select a specific date range you can do it in this format:
http://ichart.finance.yahoo.com/table.csv?s=YHOO&a=0&b=1&c=2008&d=11&e=31&f=2008&g=d
Here I’m selecting data just for the year 2008 from 01/01/08 – 12/31/08.
Let’s break down the URL string and take a look at each parameter.
s = The requested ticker symbol.
a = The starting month in two digit format. (ie: “00″ = January, “01″ = February, etc.)
b = The starting day. (ie: 1, 2, … 30, 31)
c = The starting year in four digit format (ie: “2000″)
d = The ending month in two digit format. (ie: “00″ = January, “01″ = February, etc.)
e = The ending day. (ie: 1, 2, … 30, 31)
f = The ending year in four digit format (ie: “2000″)
g = The data interval (ie: “d” = daily, “w” = weekly, ‘m’ = monthly. The default is ‘daily’ if you ignore this parameter.)
Step 2. Retrieving and Parsing the Data
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| <?
////////////////////////////////////////////////////////////////
// data.php
//
// This file will dynamiclly output the CSV locally on your
// server to overcome the security restriction in Flash .
////////////////////////////////////////////////////////////////
function ScrapePage ($url) {
$ch = curl_init($url);
curl_setopt($ch, CURLOPT_HEADER, 0);
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
$fileoutput = curl_exec($ch);
curl_close($ch);
return $fileoutput;
}
$symbol = $_REQUEST["symbol"];
$output = ScrapePage("http://ichart.finance.yahoo.com/table.csv?s=".$symbol);
$output = str_replace("Date,Open,High,Low,Close,Volume,Adj Close\n", "", $output);
echo $output;
?> |
I’m using a simple curl function to get the page. Fopen, wget or whatever your weapon of choice should work too. Since we only need the data, I’m removing the column header with a str_replace. The graphing method I will use will take the data in this format so there will be no parsing or manipulating invovlved. That’s all we need to do for this part.
Step 3. Graphing the Data
Building a full fledge charting system in Flash is quite a bit of work. Adobe has simplified this with Flex, which has built in charting support. It’s a great way to go if you have the knowledge and resources to build some very customized. But I’m gonna take this a few more steps down easy street and use a pre compiled flash suite to do the charting.
I will be using charts from amCharts.com. Not just because its free and easy, these are some really well made charts and they look really good. They have a variety of chart types.
Their stock suite can be downloaded here: http://www.amcharts.com/download
I will be using the event chart type in this example. I picked this one because it is the most familiar layout for stocks. It has the standard line chart but also includes the ability to add events. Which for a stock chart, you can labels for news, splits, dividends, etc.
From the download we will need the following files:
/amstock/amstock.swf – The flash file that displays the graph.
/amstock/swfobject.js – Standard flash embed file.
/examples/events/amstock/amstock_setting.xml – The settings file with output parameters
data.php – This is the file we created above.
Once you have all the files, place them in the same directory. Now we’ll edit the files.
First we’ll modify the amstock_setting.xml file.
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| <php
////////////////////////////////////////////////////////////////
// settings.php
//
// This file is based amstock_setting.xml (event chart type).
// I've done a bit of editing to clean up the number display
// and added some sample events.
//
// I've also converted it to php so we can dynamiclly pass
// the ticker symbol.
////////////////////////////////////////////////////////////////
?>
<?php echo '<?xml version="1.0" encoding="UTF-8"?>'; ?>
<!-- Only the settings with values not equal to defaults are in this file. If you want to see the
full list of available settings, check the amstock_settings.xml file in the amstock folder. -->
<settings>
<margins>0</margins>
<redraw>true</redraw>
<number_format>
<separator>,</separator>
<decimal_separator>.</decimal_separator>
<thousand_separator>,</thousand_separator>
<letters>
<letter number="1000">K</letter>
<letter number="1000000">M</letter>
<letter number="1000000000">B</letter>
</letters>
</number_format>
<data_sets>
<data_set did="0">
<title>East Stock</title>
<short>ES</short>
<color>7f8da9</color>
<file_name>/post-content/flashchart/data.php?symbol=<?php echo $_POST["symbol"]; ?></file_name>
<csv>
<reverse>true</reverse>
<date_format>YYYY-MM-DD</date_format>
<separator>,</separator>
<decimal_separator>.</decimal_separator>
<columns>
<column>date</column>
<column>open</column>
<column>high</column>
<column>low</column>
<column>close</column>
<column>volume</column>
<column>adj close</column>
</columns>
</csv>
<events>
<event>
<date>2007-12-25</date>
<letter>A</letter>
<description><![CDATA[Christmas Day]]></description>
</event>
<event>
<date>2008-01-01</date>
<letter>B</letter>
<description><![CDATA[New Years Day]]></description>
</event>
<event>
<date>2008-12-25</date>
<letter>C</letter>
<description><![CDATA[Christmas Day]]></description>
</event>
<event>
<date>2009-01-01</date>
<letter>D</letter>
<description><![CDATA[New Years Day]]></description>
</event>
<event>
<chart_id>second</chart_id>
<graph_id>volume</graph_id>
<date>2004-05-12</date>
<bullet>pin</bullet>
<description><![CDATA[Split 2:1]]></description>
<axis>true</axis>
<size>12</size>
</event>
<event>
<chart_id>second</chart_id>
<graph_id>volume</graph_id>
<date>2009-03-19</date>
<bullet>pin</bullet>
<description><![CDATA[Fake Dividends]]></description>
<axis>true</axis>
<size>12</size>
</event>
</events>
</data_set>
</data_sets>
<charts>
<chart cid="first">
<height>60</height>
<title></title>
<border_color>#CCCCCC</border_color>
<border_alpha>100</border_alpha>
<values>
<x>
<bg_color>EEEEEE</bg_color>
</x>
</values>
<legend>
<show_date>true</show_date>
</legend>
<column_width>100</column_width>
<events>
<color>fac622</color>
</events>
<graphs>
<graph gid="close">
<data_sources>
<close>close</close>
<high>high</high>
<low>low</low>
</data_sources>
<bullet>round_outline</bullet>
<legend>
<date key="false" title="false"><![CDATA[<b>Price:</b> {close} <b>High: </b>{high} <b>Low: </b>{low}]]></date>
<period key="false" title="false"><![CDATA[<b>Price:</b> {close} <b>High: </b>{high} <b>Low: </b>{low}]]></period>
</legend>
</graph>
</graphs>
</chart>
<chart cid="second">
<height>30</height>
<title></title>
<border_color>#CCCCCC</border_color>
<border_alpha>100</border_alpha>
<grid>
<y_left>
<approx_count>3</approx_count>
</y_left>
</grid>
<values>
<x>
<enabled>false</enabled>
</x>
</values>
<legend>
<show_date>true</show_date>
</legend>
<column_width>0</column_width>
<events>
<color>db4c3c</color>
</events>
<graphs>
<graph gid="volume">
<type>column</type>
<data_sources>
<close>volume</close>
</data_sources>
<period_value>average</period_value>
<alpha>100</alpha>
<fill_alpha>0</fill_alpha>
<legend>
<date key="false" title="false"><![CDATA[<b>Volume:</b> {close}]]></date>
<period key="false" title="false"><![CDATA[<b>Volume:</b> {close}]]></period>
</legend>
</graph>
</graphs>
</chart>
</charts>
<date_formats>
<events>DD month YYYY</events>
</date_formats>
<data_set_selector>
<enabled>false</enabled>
</data_set_selector>
<period_selector>
<periods>
<period type="DD" count="10">10D</period>
<period type="MM" count="1">1M</period>
<period type="MM" count="3">3M</period>
<period selected="true" type="YYYY" count="1">1Y</period>
<period type="YTD" count="0">YTD</period>
<period type="MAX">MAX</period>
</periods>
<periods_title>Zoom:</periods_title>
<custom_period_title>Custom period:</custom_period_title>
</period_selector>
<header>
<enabled>false</enabled>
</header>
<scroller>
<graph_data_source>close</graph_data_source>
<resize_button_style>dragger</resize_button_style>
<playback>
<enabled>true</enabled>
<speed>3</speed>
</playback>
</scroller>
</settings> |
What I did here was cleaned up some of the XML and added some sample events. I’ve also changed the extension to php since we will be dynamically passing the ticker symbol to the data.php file.
Next we put everything together to display the graph:
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| <?
////////////////////////////////////////////////////////////////
// index.php
//
// Displays the graph and takes a requested symbol
////////////////////////////////////////////////////////////////
?>
<?php
$symbol = $_REQUEST["symbol"];
if (!$symbol) {
// if no symbol is inputted defaults to yahoo
$symbol = "YHOO";
}
?>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<title>Flash Chart</title>
</head>
<body bgcolor="#FFFFFF">
<!-- saved from url=(0013)about:internet -->
<!-- amstock script-->
<script type="text/javascript" src="swfobject.js"></script>
<div id="flashcontent">
<strong>You need to upgrade your Flash Player</strong>
</div>
<script type="text/javascript">
// <![CDATA[
var so = new SWFObject("amstock.swf", "amstock", "550", "300", "8", "#FFFFFF");
so.addVariable("path", "");
so.addVariable("settings_file", encodeURIComponent("settings.php?symbol=<?php echo $symbol; ?>"));
so.write("flashcontent");
// ]]>
</script>
<!-- end of amstock script -->
<br>
<form method="post" action="<?php echo $_SERVER['PHP_SELF']; ?>">
Enter Symbol: <input name="symbol" type="text" value="<?php echo $symbol; ?>" />
<input name="submit" type="submit" value="Go" />
</form>
</body>
</html> |
The form passes our ticker symbol to the setting file which will dynamiclly call the data file with the appropriate symbol.
So there you have it…a nice looking flash graph with historical data. I’ve left out some error checking for the bare minimum to get this done. You can use this technique for other series data. There is one hiccup to all this. It lacks intraday data. That’s pretty vital information when dealing with stock price. However its just a matter of obtaining a feed. Unfortunately, I haven’t been able to find a free source for this data. This would surely seal the deal in creating a no cost flash stock chart that would rival Yahoo and Google.
UPDATE
You can now get intraday data at this URL: http://chartapi.finance.yahoo.com/instrument/1.0/YHOO/chartdata;type=quote;range=1d/csv/. Just change the YHOO to your desired ticker symbol. Thanks to Saurabh for providing the link.
UPDATE:
When I initially made this post two years ago, there were not a lot of options for flash chart output with external user defined data. As of now Google has a very robust API for displaying data and I would recommend trying out some of their charting tools. Using their API is very similar to the process I detailed here with AM Charts. I won’t go into detail since there is a wealth of documentation from Google. I would recommend this chart type to implement stock charts: http://code.google.com/apis/visualization/documentation/gallery/annotatedtimeline.html. To learn more about their charting API go here: http://code.google.com/apis/visualization/interactive_charts.html. Combining Google’s charting API and data from providers like Yahoo we can create some pretty amazing visualization of data.
