Question

我正在使用API获取列车的实际数据时间，并且我正在尝试将最近的列车时间用于用户输入的时间，然后显示列车时间，接下来的4列车已经开始运行。我正在阅读信息，代码经历了它应该做的事情，但是当我看到数组时，7个单元格中的一堆[]括号而不是计算出的数字。有什么建议？代码如下，API

测试值： requestStationSelected =＆＃39;大学％20City＆＃39;和requestEndStation =＆＃39; Roslyn＆＃39;

%this is the API link for the live data from Septa this will get 30
%results and see which time is closer to the user entered time
requestInfoSeptaLive = ['http://www3.septa.org/hackathon/NextToArrive/' requestStationSelected '/' requestEndStation '/30'];

%Again tries to get the information and if there is a failure it will give
%a probable cause and terminate the program
try
    getInfoSeptaLive = urlread(requestInfoSeptaLive);
catch
    if getInfoSeptaLive ~= '[]'
        disp...
            ('Either the arrival/depart stations dont quite match up or theres a server error. Try again.');
        return;
    else
        disp('Unable to fetch the information from Septa, please try again')
        return;
    end
end
%parses the information returned from the Live API
dataReturnedFromLiveAPI = parse_json(getInfoSeptaLive);
dataReturnedFromLiveAPI = dataReturnedFromLiveAPI{1};

%gets the size of the API in case there are no trains running
sizeOfDataNoTrains = size(dataReturnedFromLiveAPI, 1);
sizeOfData = size(dataReturnedFromLiveAPI, 2);

counter = 0;

for i = 1:sizeOfData
    scanForClosestTime = dataReturnedFromLiveAPI{1,i}.orig_departure_time;

    trainTimeGivenH = sscanf(scanForClosestTime, '%i');
    findColonTrain = strfind(scanForClosestTime, ':');
    trainTimeGivenMStr = scanForClosestTime(findColonTrain+1:4);
    trainTimeGivenM = int32(str2num(trainTimeGivenMStr));
    trainDepartTimeM = (trainTimeGivenH(1,1) * 60) + (trainTimeGivenM);

    differenceBetweenTimes = trainDepartTimeM - userEnteredMins;
    if trainDepartTimeM < userEnteredMins
        differenceBetweenTimes = userEnteredMins - trainDepartTimeM;
    end

    stopAtEndOfData = sizeOfData;
    goodTimeFrame = 60;
    closestTime = cell(1, stopAtEndOfData);
    storeTheDifference = cell(1, stopAtEndOfData);

    if(differenceBetweenTimes < 60)
        if (counter < 5)
            closestTime{i} = scanForClosestTime;
            storeTheDifference{i} = differenceBetweenTimes;
            counter = counter + 1;
        end
    end
end

Answer 1

您在for循环中分配您的单元格数组：

for i = 1:sizeOfData
    ...
        closestTime = cell(1, stopAtEndOfData);
        storeTheDifference = cell(1, stopAtEndOfData);
    ...
end

这意味着在循环的每次迭代中将它们都转换为{[],[],[],[],[]...}的数组 - 所以除非最后一次迭代中有一个有效的“最接近时间”，否则你的单元格数组将是所有空数组 - 如果是的话，除了最后一个元素之外的所有元素仍然是[]。

要解决此问题，请在开始for循环之前将两行移至。

第二个问题似乎是存储结果的数组的索引。如果您只想要五个结果，我假设您要将它们存储在数组的元素1 - 5中，而不是存储在“任何”位置。我会将代码更改为

if (counter < 5) counter = counter + 1; closestTime{counter} = scanForClosestTime; storeTheDifference{counter} = differenceBetweenTimes; end

但也许我误解了你想怎么处理它？</ p>
与您的问题无关，您可能需要查看
行
trainTimeGivenMStr = scanForClosestTime(findColonTrain+1:4);

这很可能不是你打算做的 - 看一下响应的例子，我找到了字符串"orig_departure_time":"11:57PM"。我希望findColonTrain == 3，以便上面的行成为

trainTimeGivenMStr = scanForClosestTime(4:4);

只是一个角色。也许你的意思是

trainTimeGivenMStr = scanForClosestTime（findColonTrain +（1：4））;

会变成

trainTimeGivenMStr = scanForClosestTime(4:7);

这样

trainTimeGivenMStr = '57PM';

我希望这三件事能帮助你完成所有工作！
编辑：今天早上有机会运行你的代码 - 发现了许多其他问题。我在下面添加了带注释的“工作”代码：最大的问题很可能是您没有在代码中处理AM / PM。请注意，我使用了不同的json解析器 - 这稍微改变了几行。我相信你可以把它放回去以你想要的方式工作。这会在所有单元格中返回有效数据。

dataReturnedFromLiveAPI = loadjson(getInfoSeptaLive); % next line not needed - loadjson returns struct array, not cell array %dataReturnedFromLiveAPI = dataReturnedFromLiveAPI{1}; %gets the size of the API in case there are no trains running sizeOfDataNoTrains = size(dataReturnedFromLiveAPI, 1); sizeOfData = size(dataReturnedFromLiveAPI, 2); counter = 0; stopAtEndOfData = sizeOfData; closestTime = cell(1, stopAtEndOfData); storeTheDifference = cell(1, stopAtEndOfData); userEnteredMins = 12*60+30; % looking for a train around 12:30 pm for ii = 1:sizeOfData scanForClosestTime = dataReturnedFromLiveAPI(ii).orig_departure_time; trainTimeGivenH = sscanf(scanForClosestTime, '%i'); % since we'll be considering AM/PM, have to set 12 = 0: if (trainTimeGivenH == 12), trainTimeGivenH = 0; end findColonTrain = strfind(scanForClosestTime, ':'); % change next line to get minutes plus AM/PM: trainTimeGivenMStr = scanForClosestTime(findColonTrain+(1:4)); % look at just minutes: trainTimeGivenM = int32(str2num(trainTimeGivenMStr(1:2))); % adjust for AM/PM: if(trainTimeGivenMStr(3:4)=='PM'), trainTimeGivenH = trainTimeGivenH+12; end; % compute time in minutes: trainDepartTimeM = (trainTimeGivenH * 60) + (trainTimeGivenM); differenceBetweenTimes = trainDepartTimeM - userEnteredMins; if trainDepartTimeM < userEnteredMins differenceBetweenTimes = userEnteredMins - trainDepartTimeM; end % added a couple of lines to see what is happening: fprintf(1, 'train %d: depart %s - in minutes this is %d vs user entered %d\n', ... ii, scanForClosestTime, trainDepartTimeM, userEnteredMins); goodTimeFrame = 60; if(differenceBetweenTimes < 600) if (counter < 10) counter = counter + 1; closestTime{counter} = scanForClosestTime; storeTheDifference{counter} = differenceBetweenTimes; end end end

将Int附加到数组Matlab

1 个答案: