从Musicxml中提取信息

时间:2013-01-30 12:37:36

标签: python musicxml

我是编程和Python的新手,但我目前的很多研究都是关注从musicxml文件中提取数据。我有一段音乐,想要提取不属于关键签名一部分的意外事件。我不知道怎么做,请有人帮忙吗?以下是我正在查看的musicxml文件中的一个度量示例:

<measure number='19'>
        <print new-system='no'/>
        <note>
            <rest/>
            <duration>768</duration>
            <voice>1</voice>
            <type>quarter</type>
            <staff>1</staff>
        </note>
        <backup>
            <duration>768</duration>
        </backup>
        <note>
            <pitch>
                <step>E</step>
                <octave>4</octave>
            </pitch>
            <duration>2304</duration>
            <tie type='start'/>
            <voice>2</voice>
            <type>half</type>
            <dot/>
            <staff>1</staff>
            <notations>
                <tied type='start'/>
                <slur type='stop' number='1'/>
            </notations>
        </note>
        <backup>
            <duration>1536</duration>
        </backup>
        <note>
            <pitch>
                <step>E</step>
                <alter>3</alter>
                <octave>3</octave>
            </pitch>
            <duration>1536</duration>
            <voice>1</voice>
            <type>half</type>
            <staff>1</staff>
        </note>
        <note>
            <chord/>
            <pitch>
                <step>G</step>
                <alter>4</alter>
                <octave>3</octave>
            </pitch>
            <duration>1536</duration>
            <voice>1</voice>
            <type>half</type>
            <staff>1</staff>
        </note>
        <backup>
            <duration>2304</duration>
        </backup>
        <note>
            <pitch>
                <step>E</step>
                <octave>2</octave>
            </pitch>
            <duration>2304</duration>
            <voice>5</voice>
            <type>half</type>
            <dot/>
            <staff>2</staff>
        </note>
    </measure>

问题转化为搜索musicxml文件并计算次数

<pitch>
   <step>*</step>
   <alter>**</alter>
       ...

在*不是(F或C)的情况下发生,并且还发现*为F或C且未跟<alter>标记的次数。

非常感谢任何帮助或建议!

2 个答案:

答案 0 :(得分:5)

我无法提供Python详细信息,但我有两个与MusicXML相关的建议:

1)你的问题是用偶然事件来表达的,但是你的代码关注的是alter元素。 alter元素用于音高变换;意外因素是用于书面意外的。你在找哪一个?在MusicXML中,声音的多少以及它在符号中的显示方式之间的二重性很常见,对于使用MusicXML文件进行研究非常重要。

2)如果您不熟悉编程和Python,我建议使用专为音乐学设计的高级工具包,并提供良好的MusicXML支持。您将把问题域移到更高的级别,这可以让您更快地取得进展。对此的明显选择是music21工具包,它也是用Python编写的。在http://web.mit.edu/music21/处有更多信息。

祝你的研究好运!

答案 1 :(得分:3)

python有一个xml.dom模块,允许您快速浏览xml文件。如果您有任何Web开发经验,它与javascript的文档对象模型非常相似。

from xml.dom.minidom import parse, parseString

def get_step(note):
    stepNode = note.getElementsByTagName("step")[0]
    #get the text from the Text Node within the <step>,
    #and convert it from unicode to ascii
    return str(stepNode.childNodes[0].nodeValue)

def get_alter(note):
    alters = note.getElementsByTagName("alter")
    if len(alters) == 0:
        return None
    return alters[0]

def is_rest(note):
    return len(note.getElementsByTagName("rest")) > 0

def is_accidental(note):
    return get_alter(note) != None

dom = parse("data.xml")

notes = dom.getElementsByTagName("note")
#rests don't have steps or alters, so we don't care about them. Filter them out.
notes = filter(lambda note: not is_rest(note), notes)

#compile a list of notes of all accidentals (notes with <alter> tags)
accidentals = filter(is_accidental, notes)
#remove notes that are F or C
accidentals_that_are_not_f_or_c = filter(lambda note: get_step(note) not in ["F", "C"], accidentals)

#compile a list of notes that don't contain the alter tag
non_accidentals = filter(lambda note: not is_accidental(note), notes)
#remove notes that are not F or C
non_accidentals_that_are_f_or_c = filter(lambda note: get_step(note) in ["F", "C"], non_accidentals)

print "Accidental notes that are not F or C:"
if len(accidentals_that_are_not_f_or_c) == 0:
    print "(None found)"
else:
    for note in accidentals_that_are_not_f_or_c:
        print get_step(note)

print "Non-accidental notes that are F or C:"
if len(non_accidentals_that_are_f_or_c) == 0:
    print "(None found)"
else:
    for note in non_accidentals_that_are_f_or_c:
        print get_step(note), get_step(note) in ["F", "C"]

输出:

Accidental notes that are not F or C:
E
G
Non-accidental notes that are F or C:
(None found)