blocks|key|2111148|text|看起来，您正在寻找GroupBy+(Linq)：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|2111149|line+#0+-+group+#0+
line+#1+-+group+#0+
...
line+#6+-+group+#0
line+#7+-+group+#1
...
line+#13+-+group+#1
line+#14+-+group+#2
...|code-block|syntax|javascript|2111150|代码：|BOLD|2111151|+++using+System.IO;+
+++using+System.Linq;
+++...

+++public+static+List<Settlement>+ReadFromLogFile()+{
+++++string+filename+=+Path.Combine(path,+@"BM_DB_MIGRATION.txt");

+++++if+(File.Exists(filename))+{
+++++++return+File
+++++++++.ReadLines(filename)
+++++++++.Select((line,+index)+=>+new+{
++++++++++++line,
++++++++++++index
++++++++++})+
+++++++++.GroupBy(item+=>+item.index+/+7,+//+group+of+[0..6]+lines,+then+[7..13]+lines+etc.+
++++++++++++++++++item+=>+item.line)
+++++++++.Select(group+=>+group.ToArray())+//+Let's+optimize+group+items+access
+++++++++.Select(group+=>+new+Settlement(+//+turn+7+lines+into+Settlement
++++++++++++//TODO:+put+the+right+Settlement+constructor's+syntax+here
++++++++++++group.ElementAtOrDefault(0),++//+...OrDefault+-+null,+if+line+doesn't+exist++
++++++++++++group.ElementAtOrDefault(1),
++++++++++++group.ElementAtOrDefault(2),+
++++++++++++group.ElementAtOrDefault(3),++
++++++++++++group.ElementAtOrDefault(4),
++++++++++++group.ElementAtOrDefault(5),+
++++++++++++group.ElementAtOrDefault(6)++
++++++++++))
+++++++++.ToList();++
+++++}

+++++return+new+List<Settlement>();+
+++}|2111152|entityMap^0|9|7|0|0|0|3|0|0^^$0|@$1|2|3|4|5|6|7|R|8|@$9|S|A|T|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|U|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|V|8|@$9|W|A|X|B|M]]|D|@]|E|$]]|$1|N|3|O|5|H|7|Y|8|@]|D|@]|E|$I|J]]|$1|P|3|-4|5|6|7|Z|8|@]|D|@]|E|$]]]|Q|$]]

It seems, you are looking for <code>GroupBy</code> (Linq):

<pre><code>line #0 - group #0 
line #1 - group #0 
...
line #6 - group #0
line #7 - group #1
...
line #13 - group #1
line #14 - group #2
...
</code></pre>

Code:

<pre><code> using System.IO; 
 using System.Linq;
 ...

 public static List&lt;Settlement&gt; ReadFromLogFile() {
 string filename = Path.Combine(path, @"BM_DB_MIGRATION.txt");

 if (File.Exists(filename)) {
 return File
 .ReadLines(filename)
 .Select((line, index) =&gt; new {
 line,
 index
 }) 
 .GroupBy(item =&gt; item.index / 7, // group of [0..6] lines, then [7..13] lines etc. 
 item =&gt; item.line)
 .Select(group =&gt; group.ToArray()) // Let's optimize group items access
 .Select(group =&gt; new Settlement( // turn 7 lines into Settlement
 //TODO: put the right Settlement constructor's syntax here
 group.ElementAtOrDefault(0), // ...OrDefault - null, if line doesn't exist 
 group.ElementAtOrDefault(1),
 group.ElementAtOrDefault(2), 
 group.ElementAtOrDefault(3), 
 group.ElementAtOrDefault(4),
 group.ElementAtOrDefault(5), 
 group.ElementAtOrDefault(6) 
 ))
 .ToList(); 
 }

 return new List&lt;Settlement&gt;(); 
 }
</code></pre>

blocks|key|2742166|text|一个没有LINQ的例子：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2742167|public+static+List<Settlement>+ReadFromLogFile()
{
++++string+filename+=+path+%2B+@"\BM_DB_MIGRATION.txt";
++++List<Settlement>+settlements+=+new+List<Settlement>();

++++if+(File.Exists(filename))
++++{
++++++++string[]+lines+=+File.ReadAllLines(filename);

++++++++//+Reading+7+elements+from+lines+into+an+object+of+Settelment+at+each+iteration+
++++++++//+and+store+the+object+in+a+list+of+objects...
++++++++var+record+=+new+List<string>(7);
++++++++foreach+(var+line+in+lines)
++++++++{
++++++++++++if+(record.Count+==+7)
++++++++++++{
++++++++++++++++//+convert+the+lines+to+the+Settlement+data+structure
++++++++++++++++var+s+=+new+Settlement(record);
++++++++++++++++settlements.Add(s);
++++++++++++++++record.Clear();
++++++++++++}

++++++++++++record.Add(line);
++++++++}
++++}

++++return+settlements;
}|code-block|syntax|javascript|2742168|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

An example without LINQ:

<pre><code>public static List&lt;Settlement&gt; ReadFromLogFile()
{
 string filename = path + @"\BM_DB_MIGRATION.txt";
 List&lt;Settlement&gt; settlements = new List&lt;Settlement&gt;();

 if (File.Exists(filename))
 {
 string[] lines = File.ReadAllLines(filename);

 // Reading 7 elements from lines into an object of Settelment at each iteration 
 // and store the object in a list of objects...
 var record = new List&lt;string&gt;(7);
 foreach (var line in lines)
 {
 if (record.Count == 7)
 {
 // convert the lines to the Settlement data structure
 var s = new Settlement(record);
 settlements.Add(s);
 record.Clear();
 }

 record.Add(line);
 }
 }

 return settlements;
}
</code></pre>

blocks|key|1302254|text|假设您的解决方案类的构造函数接受一个字符串数组，这将使用跳过和拿走+LINQ方法一次读取7行，同时迭代您从文件中读取的行：|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1302255|public+static+List<Settlement>+ReadFromLogFile()
{
++++string+filename+=+path+%2B+@"\BM_DB_MIGRATION.txt";
++++List<Settlement>+settlements+=+new+List<Settlement>();

++++if+(File.Exists(filename))
++++{
++++++++string[]+lines+=+File.ReadAllLines(filename);

++++++++//+Reading+7+elements+from+lines+into+an+object+of+Settelment+at+each+iteration+
++++++++//+and+store+the+object+in+a+list+of+objects...

++++++++for(int+i+=+0;+i+<+lines.length;+i+%2B=+7)
++++++++{
++++++++++++var+obj+=+lines.Skip(i).Take(7).ToArray();
++++++++++++var+settlement+=+new+Settlement(obj);

++++++++++++settlements.Add(settlement);
++++++++}
++++}

++++return+settlements;
}|code-block|syntax|javascript|1302256|entityMap|0|LINK|mutability|MUTABLE|url|https://learn.microsoft.com/en-us/dotnet/api/system.linq.enumerable.skip|1|https://learn.microsoft.com/en-us/dotnet/api/system.linq.enumerable.take^0|S|2|0|V|2|1|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@$A|T|B|U|1|V]|$A|W|B|X|1|Y]]|C|$]]|$1|D|3|E|5|F|7|Z|8|@]|9|@]|C|$G|H]]|$1|I|3|-4|5|6|7|10|8|@]|9|@]|C|$]]]|J|$K|$5|L|M|N|C|$O|P]]|Q|$5|L|M|N|C|$O|R]]]]

Assuming the constructor of your Settlement class takes an array of strings, this uses the <a href="https://learn.microsoft.com/en-us/dotnet/api/system.linq.enumerable.skip" rel="nofollow noreferrer">Skip</a> and <a href="https://learn.microsoft.com/en-us/dotnet/api/system.linq.enumerable.take" rel="nofollow noreferrer">Take</a> LINQ methods to read 7 lines at a time, while iterating through the lines you've read from the file:

<pre><code>public static List&lt;Settlement&gt; ReadFromLogFile()
{
 string filename = path + @"\BM_DB_MIGRATION.txt";
 List&lt;Settlement&gt; settlements = new List&lt;Settlement&gt;();

 if (File.Exists(filename))
 {
 string[] lines = File.ReadAllLines(filename);

 // Reading 7 elements from lines into an object of Settelment at each iteration 
 // and store the object in a list of objects...

 for(int i = 0; i &lt; lines.length; i += 7)
 {
 var obj = lines.Skip(i).Take(7).ToArray();
 var settlement = new Settlement(obj);

 settlements.Add(settlement);
 }
 }

 return settlements;
}
</code></pre>

blocks|key|2111202|text|您可以这样做，而无需将所有文件加载到内存中，也无需多次迭代。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2111203|为此，您可以使用MoreLinq批处理操作符它可在NuGet上使用。|offset|length|2111204|或者，您可以只使用下面的实现：|2111205|public+static+class+EnumerableExt
{
++++public+sealed+class+Batch<T>
++++{
++++++++public+readonly+int++++++++++++Index;
++++++++public+readonly+IEnumerable<T>+Items;

++++++++public+Batch(int+index,+IEnumerable<T>+items)
++++++++{
++++++++++++Index+=+index;
++++++++++++Items+=+items;
++++++++}
++++}

++++//+Note:+Not+threadsafe,+so+not+suitable+for+use+with+Parallel.Foreach()+or+IEnumerable.AsParallel()

++++public+static+IEnumerable<Batch<T>>+Partition<T>(this+IEnumerable<T>+input,+int+batchSize)
++++{
++++++++var+enumerator+=+input.GetEnumerator();
++++++++int+index++++++=+0;

++++++++while+(enumerator.MoveNext())
++++++++++++yield+return+new+Batch<T>(index%2B%2B,+nextBatch(enumerator,+batchSize));
++++}

++++private+static+IEnumerable<T>+nextBatch<T>(IEnumerator<T>+enumerator,+int+blockSize)
++++{
++++++++do+{+yield+return+enumerator.Current;+}
++++++++while+(--blockSize+>+0+&&+enumerator.MoveNext());
++++}
}|code-block|syntax|javascript|2111206|该实现的优点是不将临时结果存储在数组中，但它的缺点是不是threadsafe。|2111207|无论如何，考虑到这一点或MoreLinq版本，您可以通过使用它将文件批处理为七行数组来解决问题，如下所示：|2111208|if+(File.Exists(filename))
{
++++var+batchesOf7Lines+=+
++++++++File.ReadLines(filename)
+++++++.Partition(batchSize:7)
+++++++.Select(batch+=>+batch.Items.ToArray());

++++foreach+(var+batch+in+batchesOf7Lines)
++++{
++++++++//+batch[]+is+an+array+of+7+strings+(or+less+if+the+file+is+NOT+a+multiple+of+7+lines!)
++++++++//+Do+something+with+batch[].
++++}
}|2111209|这不会将整个文件的副本保存在内存中，而且它只对文件进行一次传递。它确实为每个批创建了一个由7个字符串组成的数组，但即使这样，如果使用者接受一个IEnumerable<string>，也可以避免这种情况。|style|CODE|2111210|entityMap|0|LINK|mutability|MUTABLE|url|https://www.nuget.org/packages/MoreLinq.Source.MoreEnumerable.Batch/^0|0|M|B|0|0|0|0|0|0|0|1Z|J|0^^$0|@$1|2|3|4|5|6|7|14|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|15|8|@]|9|@$D|16|E|17|1|18]]|A|$]]|$1|F|3|G|5|6|7|19|8|@]|9|@]|A|$]]|$1|H|3|I|5|J|7|1A|8|@]|9|@]|A|$K|L]]|$1|M|3|N|5|6|7|1B|8|@]|9|@]|A|$]]|$1|O|3|P|5|6|7|1C|8|@]|9|@]|A|$]]|$1|Q|3|R|5|J|7|1D|8|@]|9|@]|A|$K|L]]|$1|S|3|T|5|6|7|1E|8|@$D|1F|E|1G|U|V]]|9|@]|A|$]]|$1|W|3|-4|5|6|7|1H|8|@]|9|@]|A|$]]]|X|$Y|$5|Z|10|11|A|$12|13]]]]

You can do this without loading all of the file into memory, and without having to iterate multiple times.

To do this, you could use the MoreLinq Batch operator <a href="https://www.nuget.org/packages/MoreLinq.Source.MoreEnumerable.Batch/" rel="nofollow noreferrer">which is available on NuGet</a>.

Alternatively, you can just use the implementation below:

<pre><code>public static class EnumerableExt
{
 public sealed class Batch&lt;T&gt;
 {
 public readonly int Index;
 public readonly IEnumerable&lt;T&gt; Items;

 public Batch(int index, IEnumerable&lt;T&gt; items)
 {
 Index = index;
 Items = items;
 }
 }

 // Note: Not threadsafe, so not suitable for use with Parallel.Foreach() or IEnumerable.AsParallel()

 public static IEnumerable&lt;Batch&lt;T&gt;&gt; Partition&lt;T&gt;(this IEnumerable&lt;T&gt; input, int batchSize)
 {
 var enumerator = input.GetEnumerator();
 int index = 0;

 while (enumerator.MoveNext())
 yield return new Batch&lt;T&gt;(index++, nextBatch(enumerator, batchSize));
 }

 private static IEnumerable&lt;T&gt; nextBatch&lt;T&gt;(IEnumerator&lt;T&gt; enumerator, int blockSize)
 {
 do { yield return enumerator.Current; }
 while (--blockSize &gt; 0 &amp;&amp; enumerator.MoveNext());
 }
}
</code></pre>

This implementation has the advantage of not storing interim results in an array, but it has the disadvantage that is is not threadsafe.

Anyway, given that or the MoreLinq version, you can address your problem by using it to batch the file into arrays of seven lines like so:

<pre><code>if (File.Exists(filename))
{
 var batchesOf7Lines = 
 File.ReadLines(filename)
 .Partition(batchSize:7)
 .Select(batch =&gt; batch.Items.ToArray());

 foreach (var batch in batchesOf7Lines)
 {
 // batch[] is an array of 7 strings (or less if the file is NOT a multiple of 7 lines!)
 // Do something with batch[].
 }
}
</code></pre>

This does not keep a copy of the entire file in memory, and it makes only a single pass through the file. It does create an array of 7 strings for each batch, but even that can be avoided if your consumer accepts an <code>IEnumerable&lt;string&gt;</code>.

I'm reading strings from a text file into an <code>string[]</code>. The text file has data in sequence, for example, the first <code>7</code> elements are considered to be one record, and the next <code>7</code> elements are considered a second record, etc.

I need to store these records in objects, so at the end I will have a list of objects (<code>List&lt;Settlement&gt;</code>).

I have looked for solutions which suggest using LINQ, but I have no background in it.

Here is a sample file 

<pre class="lang-cs prettyprint-override"><code>public static List&lt;Settlement&gt; ReadFromLogFile()
{
 string filename = path + @"\BM_DB_MIGRATION.txt";
 List&lt;Settlement&gt; settlements = new List&lt;Settlement&gt;();

 if (File.Exists(filename))
 {
 string[] lines = File.ReadAllLines(filename);

 // Reading 7 elements from lines into an object of Settelment at each iteration 
 // and store the object in a list of objects...
 }

 return settlements;
}
</code></pre>

Looping though an array, taking a subset at each iteration and store into list of objects

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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我正在将字符串从文本文件读取到string[]中。文本文件有顺序的数据，例如，第一个7元素被认为是一个记录，下一个7元素被认为是第二个记录，等等。我需要将这些记录存储在对象中，所以最后我将有一个对象列表(List<Settlement>)。我一直在寻找建议使用LINQ的解决方案，但我没有它的背景。下面是一个示例文件pu...

问循环遍历数组，在每次迭代时取一个子集并存储到对象列表中。
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问循环遍历数组，在每次迭代时取一个子集并存储到对象列表中。EN