搜索两个日期之间所有日期的平均温度 [英] Searching for average temperature for all dates between two dates

问题描述

我目前正在试图弄清楚如何计算一天的平均温度.该日通常有24个测量值，00:00 01:00 ...等.文件中包含除以';'的信息.像这样:

  2020-12-30; 18:00:00; 1.9; G2020-12-30; 19:00:00; 1.3; G2020-12-30; 20:00:00; 1.1; G2020-12-30; 21:00:00; 1.0; G2020-12-30; 22:00:00; 1.1; G2020-12-30; 23:00:00; 1.3; G2020-12-31; 00:00:00; 1.1; G2020-12-31; 01:00:00; 1.4; G2020-12-31; 02:00:00; 1.9; G2020-12-31; 03:00:00; 1.9; G2020-12-31; 04:00:00; 2.4; G 

我设法将数据存储在构造类型为Data的列表中:在这里，我读取文件并调用构造函数以创建一个带有以下信息的对象，即LocalDateTime，Degrees，无论测量是否批准.

  public void loadData(String filePath)抛出IOException {List< String>fileData = Files.readAllLines(Paths.get(filePath));对于(String fileDatum:fileData){List< String>list = Arrays.asList(fileDatum.split(;")));LocalDateTime localDateTime = LocalDateTime.of(LocalDate.parse(list.get(0))，LocalTime.parse(list.get(1)));double temp = Double.parseDouble(list.get(2));字符串kontroll = list.get(3);数据数据=新数据(localDateTime，kontroll，temp);vaderData.add(data);}} 

这是我要计算一天的平均温度的地方.我设法进行了一天的计算，但是我真的不了解如何继续进行第二天而不必再次遍历整个列表.我也尝试过使用Collectors类，但是那里也没有运气.

 公共列表< String>averageTemperatures(LocalDate dateFrom，LocalDate dateTo){双和= 0;int count = 0;对于(数据平均值:vaderData){如果(dateFrom.isEqual(average.getDate().toLocalDate())){sum = sum + average.getTemp();数++;}}/*映射< LocalDate，Double>平均温度= vaderData.stream().filter(数据->！Data.getDate().toLocalDate().isAfter(dateTo)&&！Data.getDate().toLocalDate().isBefore(dateFrom)).collect(Collectors.groupingBy(Data :: getDate，Collectors.averagingDouble(Data :: getTemp)));*/返回null；} 

解决方案

如果您想按日获取某个范围内的平均值，则可以使用流api进行分组，过滤和映射来执行以下操作:

  Map< LocalDate，Double>平均值= vaderData.stream().collect(Collectors.groupingBy(d-> d.localDateTime.toLocalDate())).entrySet()//地图项集，键为本地日期，值为数据列表.stream()//地图条目流//进行过滤，以便仅从<和<被认为.filter(e->(e.getKey().isEqual(from)|| e.getKey().isAfter(from))&& e.getKey().isBefore(to))//映射条目，使键为本地日期，值为该日的平均温度.map(e->新的AbstractMap.SimpleEntry<>(e.getKey()，e.​​getValue().stream().mapToDouble(d-> d.temp).平均().orElse(Double.NaN)))//将其全部收集为地图，以key为日，以value为平均值.collect(Collectors.toMap(AbstractMap.SimpleEntry :: getKey，AbstractMap.SimpleEntry :: getValue)); 

假设:

数据类定义如下

  class数据{最后的LocalDateTime localDateTime;最终String kontroll;最终双温度；数据(LocalDateTime localDateTime，字符串控制，双温度){this.localDateTime = localDateTime;this.kontroll = kontroll;this.temp = temp;}} 

上面使用的from/to参数类似于

  LocalDate from = LocalDate.parse("2020-12-30");LocalDate ＝ LocalDate.parse("2020-12-31")； 

它们是这样的，即from是包容性的，而to是排斥性的.

使用以上输入，您将获得

  {2020-12-30 = 1.2833333333333334} 

使用提供的数据对应于2020-12-30的平均温度.

修改

从注释中获取计数和其他信息，请查看 summaryStatistics()方法.此处的更多信息: DoubleSummaryStatistics .

示例

使用 summaryStatistics 在 mapToDouble 位之后的

而不是 average()处，您将具有最小值，最大值，计数，总和和平均.

此时的返回类型不再是 Map< LocalDate，Double> ，而将是 Map< LocalDate，DoubleSummaryStatistics> .>

I'm currently trying to figure out how to calculate the average temperature for a day. The day usually has 24 measurements, 00:00 01:00... etc. The file contains information divided by ';'. Like this:

2020-12-30;18:00:00;1.9;G
2020-12-30;19:00:00;1.3;G
2020-12-30;20:00:00;1.1;G
2020-12-30;21:00:00;1.0;G
2020-12-30;22:00:00;1.1;G
2020-12-30;23:00:00;1.3;G
2020-12-31;00:00:00;1.1;G
2020-12-31;01:00:00;1.4;G
2020-12-31;02:00:00;1.9;G
2020-12-31;03:00:00;1.9;G
2020-12-31;04:00:00;2.4;G

I managed to store the data in a List of the constructed type Data: This is where I read the file and call the constructor to create an object with the following information, LocalDateTime, Degrees, whether the measurement was approved or not.

public void loadData(String filePath) throws IOException {
    List<String> fileData = Files.readAllLines(Paths.get(filePath));
    for (String fileDatum : fileData) {
        List<String> list = Arrays.asList(fileDatum.split(";"));
        LocalDateTime localDateTime = LocalDateTime.of(
                LocalDate.parse(list.get(0)), LocalTime.parse(list.get(1)));
        double temp = Double.parseDouble(list.get(2));
        String kontroll = list.get(3);
        Data data = new Data(localDateTime, kontroll, temp);
        vaderData.add(data);
    }
}

This is where I am trying to calculate the average temperature of a day. I manage to calculate for one day, but don't really understand how I can go on to the next day without having to iterate the entire list again. I also experimented with using the Collectors class but had no luck there neither.

public List<String> averageTemperatures(LocalDate dateFrom,
                                        LocalDate dateTo) {
    double sum = 0;
    int count = 0;
    for (Data average : vaderData) {
        if (dateFrom.isEqual(average.getDate().toLocalDate())) {
            sum = sum + average.getTemp();
            count++;
        }
    }
    /*
    Map<LocalDate, Double> Averagetemperature = vaderData.stream()
            .filter(Data -> !Data.getDate().toLocalDate().isAfter(dateTo)
                    && !Data.getDate().toLocalDate().isBefore(dateFrom))
            .collect(Collectors.groupingBy(Data::getDate,
                    Collectors.averagingDouble(Data::getTemp)));
    */
    return null;
}

解决方案

If you want to get averages by day in a range you can use the stream api with grouping, filtering and mapping to do something like this:

Map<LocalDate, Double> averages = vaderData.stream()
        .collect(Collectors.groupingBy(d -> d.localDateTime.toLocalDate()))
        .entrySet() // set of map entries with key as local date and value as list of data
        .stream() // stream of map entries
        // filter such that only dates >= from and < to are considered
        .filter(e -> (e.getKey().isEqual(from) || e.getKey().isAfter(from)) && e.getKey().isBefore(to))
        // map entries such that key is local date and value is average temp for that day
        .map(e -> new AbstractMap.SimpleEntry<>(e.getKey(), e.getValue().stream()
                .mapToDouble(d -> d.temp)
                .average()
                .orElse(Double.NaN)))
        // collect it all as a map with key as the day and value as the average
        .collect(Collectors.toMap(
                AbstractMap.SimpleEntry::getKey,
                AbstractMap.SimpleEntry::getValue));

Assumptions:

The data class is defined as follows

class Data {
    final LocalDateTime localDateTime;
    final String kontroll;
    final double temp;

    Data(LocalDateTime localDateTime, String kontroll, double temp) {
        this.localDateTime = localDateTime;
        this.kontroll = kontroll;
        this.temp = temp;
    }
}

The from / to parameters used in the above are something like

LocalDate from = LocalDate.parse("2020-12-30");
LocalDate to = LocalDate.parse("2020-12-31");

And they are such that from is inclusive and to is exclusive.

With the above input you'll get

{2020-12-30=1.2833333333333334}

Corresponding with the average temperature for 2020-12-30 with the provided data.

Edit

From the comments, to get counts and other information, look at the summaryStatistics() method. More info here: DoubleSummaryStatistics.

Example

after the mapToDouble bit, instead of average(), with summaryStatistics you would have information for min, max, count, sum and average.

The return type on it at that point isn't a Map<LocalDate, Double> anymore, it would be a Map<LocalDate, DoubleSummaryStatistics>.

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