javascript - 使用 PapaParse 正确解析本地文件

Question

我需要解析一些本地文件，我找到了 PapaParse 库。

看来必须有一个File的实例才能解析本地文件。

所以我在我的 hmtl 中创建了这个:

<label class="control-label">Files:</label>
<span class="btn btn-default btn-file">Browse 
    <input id="file-input" type="file" accept="text/comma-separated-values" runat="server" multiple> 
</span>
<script type="text/javascript">
var fileInput = document.getElementById('file-input');
fileInput.addEventListener('change', function(event) 
{
    var input = event.target;
    console.log(input.files);
    if (input.files.length > 0)
    loadNoisePerRegion(input.files);
});
</script>

这是负责解析文件的函数:

function loadNoisePerRegion(files)
{
    regions_count = 149
    complaints_type = 18
    time_slots = 24

    console.log(files);
    for (i = 0; i < files.length; i++)
    {
        var results = Papa.parse(files[i], {delimiter:',', dynamicTyping:true, skipEmptyLines:true});
        console.log(results);
    }
}

第一个 console.log 正确打印文件列表:

但是应该打印已解析文件的那个打印undefined:

我也试过这个:

function loadNoisePerRegion(files)
{
    regions_count = 149
    complaints_type = 18
    time_slots = 24

    var data;
    for (i = 0; i < files.length; i++)
    {
        Papa.parse(files[i], {delimiter:',', dynamicTyping:true, skipEmptyLines:true, 
                              complete: function(results) {
                                  data = results;
                              }});
        console.log(data);
    }
}

但得到了相同的结果。

具体来说，我正在读取 24 个文件，每个文件有 149 行和 18 列，我必须能够填充尺寸为 149x18x24 的 3D 数组。文件中的数字表示它的 z 坐标，所以我不能在完整的函数中执行此操作，因为我必须能够拆分文件名并获取其编号。

我绝对不是 JavaScript/web 方面的专家，而且我已经为此苦苦挣扎了一段时间。我希望能够检索解析的结果。

这是A0第一行的例子:

4.132523767643456539e-03,3.338056650702859052e-03,5.094068820554688640e-03,4.319352199708446222e-03,3.336436748977582127e-03,4.538557367580550554e-03,5.078650751493581431e-03,4.555551665273932863e-03,5.084069822892055800e-03,3.686315220687433510e-03,2.865154886232469320e-03,3.818313965958328778e-03,9.116708509848362590e-03,4.716984235548558543e-03,2.144280439848759989e-03,4.815674842039764994e-03,1.300910635568432172e-02,3.749492079670652123e-03
4.842012184270096282e-03,3.998360423928741351e-03,6.032359742843619241e-03,5.069118478958277614e-03,3.962735680903891645e-03,5.348581710052801100e-03,6.060137695773112031e-03,5.456990595265281616e-03,5.929390713573804740e-03,4.525055239080687589e-03,3.383705283438338644e-03,4.551759343211069647e-03,1.095692751267150940e-02,5.597012676156478198e-03,2.567732343893020051e-03,5.685926667065896445e-03,1.560915350120501387e-02,4.443829783777414333e-03
4.079989698805746787e-03,3.328350814870313038e-03,5.064522763420175287e-03,4.279040870552436142e-03,3.301293219296043413e-03,4.510432110952588246e-03,5.086058753331568205e-03,4.616797276325930628e-03,4.992062862149935880e-03,3.795785069074858985e-03,2.847335417364839187e-03,3.825286632147210670e-03,9.187299184630516938e-03,4.702130566580337880e-03,2.154081923639708518e-03,4.794475788747958739e-03,1.308373500947002457e-02,3.740793852106250213e-03
4.563089873902198210e-03,3.698136656951233302e-03,5.580712767255690231e-03,4.685044796514505581e-03,3.691000289311937525e-03,5.061749072305680476e-03,5.581128473400761604e-03,5.020678289539204017e-03,5.608299405212476170e-03,4.112740183672113255e-03,3.135547056402714344e-03,4.232133388454519321e-03,1.007938274081057912e-02,5.142988594427083324e-03,2.359850897493935215e-03,5.291499589116757836e-03,1.442981513073606642e-02,4.126617150374075130e-03
4.233079253488222435e-03,3.429572268677020391e-03,5.201183960582634117e-03,4.384982857959412658e-03,3.428921943591476795e-03,4.663825521041545762e-03,5.208280682626760701e-03,4.652072830356355007e-03,5.196356179840076923e-03,3.807794003893105652e-03,2.922879953390736339e-03,3.923911693425461561e-03,9.352487080015160770e-03,4.815088529020412900e-03,2.188854161909735679e-03,4.918000845203720876e-03,1.339029515720328335e-02,3.842932179350835691e-03
5.018398813023945346e-03,4.098671680623462016e-03,6.175658180051601769e-03,5.237731466313167578e-03,4.059449902364497924e-03,5.493950666372676706e-03,6.135141982050259027e-03,5.512998808377303321e-03,6.143022353621389701e-03,4.456614028740587402e-03,3.476316043953285584e-03,4.604894264047694301e-03,1.105308488032731747e-02,5.709255537811516561e-03,2.590043773584999216e-03,5.821526147293040222e-03,1.573699869615532640e-02,4.519518360853568527e-03
3.132467419940661128e-03,2.545321960200405860e-03,3.832573828202544882e-03,3.219085400230973799e-03,2.533236139757844094e-03,3.470792448931643050e-03,3.830019218544809898e-03,3.433095359961642248e-03,3.850057311333613015e-03,2.815480757636485646e-03,2.168510683532243622e-03,2.894682090130531061e-03,6.894608763609650325e-03,3.538159290341114788e-03,1.612202627944366289e-03,3.637956820248035641e-03,9.893755519784832100e-03,2.837906417687549761e-03
4.800994519050426172e-03,3.934758744674650074e-03,5.934009792383837870e-03,4.992194166235072728e-03,3.917566441980549312e-03,5.291603326034871602e-03,5.916095422178331911e-03,5.328262870980130309e-03,5.903321662169932170e-03,4.375161755177821125e-03,3.312165225394205631e-03,4.468951997999968777e-03,1.071433819952720412e-02,5.484077525602872386e-03,2.506901090683472198e-03,5.593659544787319381e-03,1.529675422306276886e-02,4.363816472038692384e-03
5.570229804289797415e-03,4.562799356373183762e-03,6.879016052102292916e-03,5.812839576211367883e-03,4.521082251277935143e-03,6.128983088529497275e-03,6.847093515298881966e-03,6.158292373616840697e-03,6.872845601896844688e-03,5.021595363099932291e-03,3.861107109964561235e-03,5.148812929153878844e-03,1.233859837141527450e-02,6.380375101714370195e-03,2.874992820156773050e-03,6.503565688023313016e-03,1.764629838527919520e-02,5.071022753373630523e-03
4.126395072884211403e-03,3.376574114485871112e-03,5.008231892946810385e-03,4.164872841798445205e-03,3.354037900801269331e-03,4.594882447679036856e-03,5.015972447479648440e-03,4.460282785245711645e-03,5.045844370021141181e-03,3.683634157419656604e-03,2.836139377758035898e-03,3.805476945286162625e-03,9.047762730693695646e-03,4.590932145448584425e-03,2.114960061661486611e-03,4.744093747217716962e-03,1.298309285733738327e-02,3.696034590115754824e-03
4.292941772771790773e-03,3.489453578397746364e-03,5.298089023740347112e-03,4.452896333557184068e-03,3.499856110981013416e-03,4.733934692158318913e-03,5.315000086946645476e-03,4.759246385418459263e-03,5.270072375649033358e-03,3.923826657153102818e-03,2.947664747183619677e-03,4.016425868318176592e-03,9.588088162520781374e-03,4.903102462350410022e-03,2.243232446416389917e-03,4.993880005294899088e-03,1.370825056190460266e-02,3.910437657171024310e-03
3.755159842787435427e-03,3.039322911280831294e-03,4.632361715056376728e-03,3.931518525350640759e-03,3.038914666833290174e-03,4.102783779656862979e-03,4.597165732308097254e-03,4.085619256400913057e-03,4.626988512097271987e-03,3.288556155369262799e-03,2.608910925580669275e-03,3.444363929093285145e-03,8.212176672858654061e-03,4.289867783183640496e-03,1.930326004601609679e-03,4.367095856347332113e-03,1.173569439100231523e-02,3.396204117660583423e-03
2.398483398617096661e-03,1.909877589598136735e-03,2.961217451414360682e-03,2.513688486462039087e-03,1.951188170305110476e-03,2.611082196851768206e-03,2.954896767272728250e-03,2.599493219433874312e-03,2.970655826532853875e-03,2.104529724470539497e-03,1.649941650584158849e-03,2.220942314669266827e-03,5.261383872354382860e-03,2.748677182532607236e-03,1.242954051709330935e-03,2.785908583290144184e-03,7.545742952671409889e-03,2.185030386654985939e-03

文档说:

complete: The callback to execute when parsing is complete. It receives the parse results. If parsing a local file, the File is passed in, too:
complete: function(results, file) {
    console.log("Parsing complete:", results, file);
}
When streaming, parse results are not available in this callback.

但是，在我的案例中，此日志还会打印 undefined for file。

如有任何帮助，我们将不胜感激。

Answer 1

如果您正在解析本地文件，那么您需要使用这种格式:

// Parse local CSV file
Papa.parse(file, {
    complete: function(results) {
        console.log("Finished:", results.data);
    }
});

它在完整的回调中提供结果。我看到你试过了，但是你在 for 循环中执行 console.log(data) 的点在回调之外。因此，这将在回调完成之前记录下来。

在这种情况下，您可以尝试使用 javascript promise ，并在调用完整函数时解析每个 promise 。然后，只有在所有 promise 都已解决时才对数据采取行动......我不是这方面的专家。

或者，如果您不想等待所有文件都被解析，那么您可以在完整的内部调用您的函数:

Papa.parse(file[i], {
  complete: function(results) {
      console.log("Finished:", results.data);
      myFunc(results); // Do something with the result. Called after EACH file is parsed.
  }
});

如果您需要在加载所有文件后执行某些操作，请查看以下两个:

Using arrays

Using promises