SAM是Sequence Alignment/Map 的缩写。像bwa等软件序列比对结果都会输出这样的文件。samtools网站上有专门的文档介绍SAM文件。具体地址:http://samtools.sourceforge.net/SAM1.pdf
很多人困惑SAM文件中的第二列FLAG值是什么意思。根据文档介绍我们可以计算,但是为了方便大家,下面给大家提供一个脚本工具,大家直接输入flag值就可以知道它代表的含义了。
该脚本的使用方法如下截图所示:
脚本工具的使用方法:
将下面的代码保存在记事本里面,另存为一个html文件,如文件名:FlagExplain.html(拓展名一定要为.html)。双击既可以在浏览器里面打开了。
01 | <html><head><meta http-equiv="Content-Type" content="text/html; charset=GBK"> |
02 | <title>Explain SAM Flags</title> |
03 | <script type="text/javascript"> |
04 | lstFlags = [["read paired", 0x1], |
05 | ["read mapped in proper pair", 0x2], |
06 | ["read unmapped", 0x4], |
07 | ["mate unmapped", 0x8], |
08 | ["read reverse strand", 0x10], |
09 | ["mate reverse strand", 0x20], |
10 | ["first in pair", 0x40], |
11 | ["second in pair", 0x80], |
12 | ["not primary alignment", 0x100], |
13 | ["read fails platform/vendor quality checks", 0x200], |
14 | ["read is PCR or optical duplicate", 0x400]]; |
16 | function explainFlags() { |
17 | var flagValue = parseInt(document.getElementById('tb').value); //returns 0 or NaN if can't parse |
19 | for(var i = 0; i < lstFlags.length; i++) { |
20 | var checkbox = document.getElementById('cb' + i) |
21 | if(lstFlags[i][1] & flagValue) { |
22 | summary += " " + lstFlags[i][0] + "<br>"; |
23 | checkbox.checked = true; |
25 | checkbox.checked = false; |
29 | document.getElementById('summary').innerHTML = summary; |
32 | function checkboxClicked() { |
33 | //compute the new flag value |
35 | for(var i = 0; i < lstFlags.length; i++) { |
36 | var checkBox = document.getElementById('cb' + i); |
37 | if(checkBox.checked) { |
38 | newFlagValue |= lstFlags[i][1]; |
41 | var textbox = document.getElementById('tb'); |
42 | textbox.value = newFlagValue; |
47 | <noscript>This page requires JavaScript. Please enable it in your browser settings.</noscript> |
51 | This utility explains SAM flags in plain English. <br> |
54 | <form onsubmit="explainFlags(); return false;"> |
56 | <input id="tb" type="text" size="10"> |
57 | <input type="submit" value="Explain"><br> |
60 | <script type="text/javascript"> |
61 | for(var i = 0; i < lstFlags.length; i++) { |
62 | document.write("<input type=checkbox name=cb" + i + " id='cb" + i + "' onclick='checkboxClicked();'> " +lstFlags[i][0] + "</input><br>"); |
64 | </script><input type="checkbox" name="cb0" id="cb0" onclick="checkboxClicked();"> read paired<br><input type="checkbox" name="cb1" id="cb1"onclick="checkboxClicked();"> read mapped in proper pair<br><inputtype="checkbox" name="cb2" id="cb2" onclick="checkboxClicked();"> read unmapped<br><input type="checkbox" name="cb3" id="cb3" onclick="checkboxClicked();"> mate unmapped<br><input type="checkbox" name="cb4" id="cb4" onclick="checkboxClicked();"> read reverse strand<br><input type="checkbox" name="cb5" id="cb5" onclick="checkboxClicked();"> mate reverse strand<br><input type="checkbox" name="cb6" id="cb6" onclick="checkboxClicked();"> first in pair<br><input type="checkbox" name="cb7" id="cb7" onclick="checkboxClicked();"> second in pair<br><input type="checkbox" name="cb8" id="cb8"onclick="checkboxClicked();"> not primary alignment<br><input type="checkbox" name="cb9" id="cb9" onclick="checkboxClicked();"> read fails platform/vendor quality checks<br><input type="checkbox" name="cb10" id="cb10" onclick="checkboxClicked();"> read is PCR or optical duplicate<br> |
68 | </div></form></body></html> |
参考:https://www.plob.org/article/1697.html