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Counting and accessing items in a list of lists ie: invoice with line items

I am trying to wrap my head around C# Lists, coming from a strong PHP background and thinking of things in PHP Array terms, but I have a class that includes a list and I am trying to count distint items within it. Is there a simple linq way to do this or would I use some sort of nested foreach?
Thank you in advance
public void main() {
List<invoice> inv = new List<invoice>();
// I do something that populates inv with, say 100 invoices
// Count distinct inv.lines.rowtype ?? to get:
Type A 34
Type B 3
Type X 21 ...etc
}
class invoice {
int invoicenumber;
int customernumber;
List<lineitem> lines;
struct lineitem {
string rowtype;
string somethingelse;
int whatever;
}
public invoice {
lines = new List<lineitem>;
}
}

Something like this?
inv.SelectMany(i => i.lines).GroupBy(l => l.rowtype).ToDictionary(g => g.Key, g => g.Count())

You could probably use some LINQ for this, however for the sake of simplicity and readability, I would recommend using for loops
// Keep a dictionary for count
var lineItemDict = new Dictionary<string, int>();
foreach (var inv in invoices)
{
foreach (var line in inv.lines)
{
// If the rowtype already exists, increment the count
if (lineItemDict.ContainsKey(line.rowtype))
{
lineItemDict.TryGetValue(line.rowtype, out count);
lineItemDict[line.rowtype] = count + 1;
}
else
{
// Else add a new entry
lineItemDict.Add(line.rowtype, 1);
}
}
}
With LINQ:
// Keep a dictionary for count
var lineItemDict = new Dictionary<string, int>();
invoices.ForEach(inv => {
inv.lines.ForEach(line => {
// If the rowtype already exists, increment the count
if (lineItemDict.ContainsKey(line.rowtype))
{
lineItemDict.TryGetValue(line.rowtype, out count);
lineItemDict[line.rowtype] = count + 1;
}
else
{
// Else add a new entry
lineItemDict.Add(line.rowtype, 1);
}
});
});
Both of these will leave you with a dictionary (lineItemDict) that looks like this:
<rowtype> : <count>
For example,
'A' : 34
'B' : 3
'X' : 21

List of objects with a list as a property of the object

Declaring a list of objects:
List<object> result = new List<object>();
and a list of int to store the ids:
List<int> ids = new List<int>();
I want to store in result objects containing the pair (string, list of int).
It works fine for the pair (string, int) but I want that when there are 2 identical strings to have only one object and the int values to be stored in a list.
ex: {pars = "xxx", id = 1} , {pars = "xxx", id = 2} becomes {pars = "xxx", id = (1,2 )}
For doing the initial functionality, I use a foreach through an object from which I take the string(pars) and the id:
foreach (dataBinding in myData)
{
var x = string.Join(" ", dataBinding.Params.Select(p => p.myDescription));
result.Add(new { pars = x, id = dataBinding.Id });
}
there could be more strings in Params, that's why I use the join.
As it is here it works by creating objects having the form (string, int). But my aim is to make it (string, list of int) and if there are two objects with same string to combine them as I wrote before.
I tried to add ids list as the second property of the object but probably I'm not doing it correctly.
result.Add(new { pars = x, ids = dataBinding.Id });

You can use LINQ, especially GroupBy:
Dictionary<string, List<int>> descriptionIDs = myData
.GroupBy(x => x.myDescription)
.ToDictionary(g => g.Key, g => g.Select(x => x.Id).ToList());
Now you have even a dictionary, not just a strange List<object> that contains anonymous types.
As someone mentioned, you can also use ToLookup which i'd also prefer:
var descriptionLookup = myData.ToLookup(x => x.myDescription);
Now you can get the ID-List easily:
var result = descriptionLookup.Select(g => new { pars = g.Key, ids = g.Select(x=> x.Id).ToList() }).ToList():

Perhaps I am not understanding the scenario fully but I suspect using the following would server your purpose.
List<Dictionary<string, List<int>>>
When the key doesn't exist you add it and when it does you just add to the List.

Below program depicts the current generic collection type, also allow to add a new value if Key Already exists.
using System;
using System.Collections.Generic;
public class Program
{
public static void Main()
{
MyProgram p = new MyProgram();
p.Add("First" , 5);
p.Add("Second" , 8);
p.Add("Third" , 9);
p.Add("First" , 6);
p.Add("First" , 7);
p.PrintDictionary();
}
}
public class MyProgram
{
private Dictionary<string, List<int>> dict = new Dictionary<string, List<int>>();
public void Add(string key, int value)
{
if (dict.ContainsKey(key))
{
dict[key].Add(value);
}
else
{
dict.Add(key, new List<int>() {value});
}
}
public void PrintDictionary()
{
foreach(var keyValue in dict)
{
Console.WriteLine("Key : " + keyValue.Key);
foreach(var val in keyValue.Value)
{
Console.WriteLine(string.Format("\t Value : {0}", val));
}
}
}
}
Output :
Key : First
Value : 5
Value : 6
Value : 7
Key : Second
Value : 8
Key : Third
Value : 9
Check this Live Fiddle.

How to parse a text file with alternating lines of names and lists of integers?

I need to read a file and put that data inside to different arrays.
My .txt file looks like:
w1;
1 2 3
w2;
3 4 5
w3;
4 5 6
I tried something like the following:
int[] w1 = new int [3];
int[] w2 = new int [3];
int[] w3 = new int [3];
string v = "w1:|w2:|w3:";
foreach (string line in File.ReadAllLines(#"D:\\Data.txt"))
{
string[] parts = Regex.Split(line, v);
I got that string but I have no idea how to cut every element of it to arrays showed above.

Rather than parsing the file and putting the arrays into three hardcoded variables corresponding to hardcoded names w1, w2 and w3, I would remove the hardcoding and parse the file into a Dictionary<string, int[]> like so:
public static class DataFileExtensions
{
public static Dictionary<string, int[]> ParseDataFile(string fileName)
{
var separators = new [] { ' ' };
var query = from pair in File.ReadLines(fileName).Chunk(2)
let key = pair[0].TrimEnd(';')
let value = (pair.Count < 2 ? "" : pair[1]).Split(separators, StringSplitOptions.RemoveEmptyEntries).Select(s => int.Parse(s, NumberFormatInfo.InvariantInfo)).ToArray()
select new { key, value };
return query.ToDictionary(p => p.key, p => p.value);
}
}
public static class EnumerableExtensions
{
// Adapted from the answer to "Split List into Sublists with LINQ" by casperOne
// https://stackoverflow.com/questions/419019/split-list-into-sublists-with-linq/
// https://stackoverflow.com/a/419058
// https://stackoverflow.com/users/50776/casperone
public static IEnumerable<List<T>> Chunk<T>(this IEnumerable<T> enumerable, int groupSize)
{
// The list to return.
List<T> list = new List<T>(groupSize);
// Cycle through all of the items.
foreach (T item in enumerable)
{
// Add the item.
list.Add(item);
// If the list has the number of elements, return that.
if (list.Count == groupSize)
{
// Return the list.
yield return list;
// Set the list to a new list.
list = new List<T>(groupSize);
}
}
// Return the remainder if there is any,
if (list.Count != 0)
{
// Return the list.
yield return list;
}
}
}
And you would use it as follows:
var dictionary = DataFileExtensions.ParseDataFile(fileName);
Console.WriteLine("Result of parsing {0}, encountered {1} data arrays:", fileName, dictionary.Count);
foreach (var pair in dictionary)
{
var name = pair.Key;
var data = pair.Value;
Console.WriteLine(" Data row name = {0}, values = [{1}]", name, string.Join(",", data));
}
Which outputs:
Result of parsing Question49341548.txt, encountered 3 data arrays:
Data row name = w1, values = [1,2,3]
Data row name = w2, values = [3,4,5]
Data row name = w3, values = [4,5,6]
Notes:
I parse the integer values using NumberFormatInfo.InvariantInfo to ensure consistency of parsing in all locales.
I break the lines of the file into chunks of two by using a lightly modified version of the method from this answer to Split List into Sublists with LINQ by casperOne.
After breaking the file into chunks of pairs of lines, I trim the ; from the first line in each pair and use that as the dictionary key. The second line in each pair gets parsed into an array of integer values.
If the names w1, w2 and so on are not unique, you could deserialize instead into a Lookup<string, int []> by replacing ToDictionary() with ToLookup().
Rather than loading the entire file into memory upfront using File.ReadAllLines(), I enumerate though it sequentially using File.ReadLines(). This should reduce memory usage without any additional complexity.
Sample working .Net fiddle.

Your RegEx doesn't actually do anything, you already have an array with each line separated. What you want to do is just ignore the lines that aren't data:
var lines = File.ReadAllLines(#"D:\\Data.txt");
for (int i = 1; i < lines.Length; i += 2) // i.e indexes 1, 3 and 5
{
string[] numbers = lines[i].Split(' ');
}
Or, you could just assign given that you know the order:
w1 = lines[1].Split(' ');
w2 = lines[3].Split(' ');
w3 = lines[5].Split(' ');

Storing Word Line and Frequency based on Word

I am working on a problem, in which I have to be able to read a text file, and count the frequency and line number of a specific word.
So for example, a txt file that reads
"Hi my name is
Bob. This is
Cool"
Should return:
1 Hi 1
1 my 1
1 name 1
2 is 1 2
1 bob 2
1 this 2
1 cool 3
I am having trouble deciding how to store the line number, as well as the word frequency. I have tried a few different things, and so far this is where I am at.
Any help?
Dictionary<string, int> countDictionary = new Dictionary<string,int>();
Dictionary<string, List<int>> lineDictionary = new Dictionary<string, List<int>>();
List<string> lines = new List<string>();
System.IO.StreamReader file =
new System.IO.StreamReader("Sample.txt");
//Creates a List of lines
string x;
while ((x = file.ReadLine()) != null)
{
lines.Add(x);
}
foreach(var y in Enumerable.Range(0,lines.Count()))
{
foreach(var word in lines[y].Split())
{
if(!countDictionary.Keys.Contains(word.ToLower()) && !lineDictionary.Keys.Contains(word.ToLower()))
{
countDictionary.Add(word.ToLower(), 1);
//lineDictionary.Add(word.ToLower(), /*what to put here*/);
}
else
{
countDictionary[word] += 1;
//ADD line to dictionary???
}
}
}
foreach (var pair in countDictionary)//WHAT TO PUT HERE to print both
{
Console.WriteLine("{0} {1}", pair.Value, pair.Key);
}
file.Close();
System.Console.ReadLine();

You can pretty much do this with one line of linq
var processed =
//get the lines of text as IEnumerable<string>
File.ReadLines(#"myFilePath.txt")
//get a word and a line number for every word
//so you'll have a sequence of objects with 2 properties
//word and lineNumber
.SelectMany((line, lineNumber) => line.Split().Select(word => new{word, lineNumber}))
//group these objects by their "word" property
.GroupBy(x => x.word)
//select what you need
.Select(g => new{
//number of objects in the group
//i.e. the frequency of the word
Count = g.Count(),
//the actual word
Word = g.Key,
//a sequence of line numbers of each instance of the
//word in the group
Positions = g.Select(x => x.lineNumber)});
foreach(var entry in processed)
{
Console.WriteLine("{0} {1} {2}",
entry.Count,
entry.Word,
string.Join(" ",entry.Positions));
}
I like 0 based counting, so you may want to add 1 in the appropriate place.

You are tracking two different properties of the entity "word" in two separate data structures. I would suggest creating a class to represent that entity, something like
public class WordStats
{
public string Word { get; set; }
public int Count { get; set; }
public List<int> AppearsInLines { get; set; }
public Word()
{
AppearsInLines = new List<int>();
}
}
Then track things in a
Dictionary<string, WordStats> wordStats = new Dictionary<string, WordStats>();
Use the word itself as the key. When you encounter a new word, check whether there is already an instance of Word with that specific key. If so, get it and update the Count and AppearsInLines property; if not create a new instance and add it to the dictionary.
foreach(var y in Enumerable.Range(0,lines.Count()))
{
foreach(var word in lines[y].Split())
{
WordStats wordStat;
bool alreadyHave = words.TryGetValue(word, out wordStat);
if (alreadyHave)
{
wordStat.Count++;
wordStat.AppearsInLines.Add(y);
}
else
{
wordStat = new WordStats();
wordStat.Count = 1;
wordStat.AppearsInLines.Add(y);
wordStats.Add(word, wordStat);
}

Remove duplicated elements from a List<String>

I would like to remove the duplicate elements from a List. Some elements of the list looks like this:
Book 23
Book 22
Book 19
Notebook 22
Notebook 19
Pen 23
Pen 22
Pen 19
To get rid of duplicate elements i've done this:
List<String> nodup = dup.Distinct().ToList();
I would like to keep in the list just
Book 23
Notebook 22
Pen 23
How can i do that ?

you can do someting like
string firstElement = dup.Distinct().ToList().First();
and add it to another list if you want.

It's not 100% clear what you want here - however...
If you want to keep the "largest" number in the list, you could do:
List<string> noDup = dup.Select(s => s.Split(new[] {' '}, StringSplitOptions.RemoveEmptyEntries)
.Select(p => new { Name=p[0], Val=int.Parse(p[1]) })
.GroupBy(p => p.Name)
.Select(g => string.Join(" ", g.Key, g.Max().ToString()))
.ToList();
This would transform the List<string> by parsing the numeric portion into a number, taking the max per item, and creating the output string as you have specified.

You can use LINQ in combination with some String operations to group all your itemy by name and MAX(Number):
var q = from str in list
let Parts = str.Split(new char[] { ' ' }, StringSplitOptions.RemoveEmptyEntries)
let item = Parts[ 0 ]
let num = int.Parse(Parts[ 1 ])
group new { Name = item, Number = num } by item into Grp
select new {
Name = Grp.Key,
Value = Grp.Max(i => i.Number).ToString()
};
var highestGroups = q.Select(g =>
String.Format("{0} {1}", g.Name, g.Value)).ToList();
(Same as Reed's approach but in query syntax which is better readable to my mind)
Edit: I cannot reproduce your comment that it does not work, here is sample data:
List<String> list = new List<String>();
list.Add("Book 23");
list.Add("Book 22");
list.Add("Book 19");
list.Add("Notebook 23");
list.Add("Notebook 22");
list.Add("Notebook 19");
list.Add("Pen 23");
list.Add("Pen 22");
list.Add("Pen 19");
list.Add("sheet 3");
var q = from str in list
let Parts = str.Split(new char[] { ' ' }, StringSplitOptions.RemoveEmptyEntries)
let item = Parts[ 0 ]
let num = int.Parse(Parts[ 1 ])
group new { Name = item, Number = num } by item into Grp
select new {
Name = Grp.Key,
Value = Grp.Max(i => i.Number).ToString()
};
var highestGroups = q.Select(g => String.Format("{0} {1}", g.Name, g.Value));
MessageBox.Show(String.Join(Environment.NewLine, highestGroups));
The result:
Book 23
Notebook 23
Pen 23
sheet 3

You may want to add a custom comparer as a parameter, as you can see in the example on MSDN.
In this example I assumed Foo is a class with two members.
class Program
{
static void Main(string[] args)
{
var list = new List<Foo>()
{
new Foo("Book", 23),
new Foo("Book", 22),
new Foo("Book", 19)
};
foreach(var element in list.Distinct(new Comparer()))
{
Console.WriteLine(element.Type + " " + element.Value);
}
}
}
public class Foo
{
public Foo(string type, int value)
{
this.Type = type;
this.Value = value;
}
public string Type { get; private set; }
public int Value { get; private set; }
}
public class Comparer : IEqualityComparer<Foo>
{
public bool Equals(Foo x, Foo y)
{
if(x == null || y == null)
return x == y;
else
return x.Type == y.Type;
}
public int GetHashCode(Foo obj)
{
return obj.Type.GetHashCode();
}
}
This works on an IList, assuming that we want the first item each, not the one with the highest number. Be careful with different collection types (like ICollection or IEnumerable), as they do not guarantee you any order. Therefore any of the Foos may remain after the Distinct.
You could also override both Equals and GetHashCode of Foo instead of using a custom IEqualityComparer. However, I would not actually recommend this for a local distinct. Consumers of your class may not recognize that two instances with same value for Type are always equal, regardless of their Value.

a bit old fashioned , but it should work ,
If I understand correctrly
Dictionary<string,int> dict=new Dictionary<string,int>();
//Split accepts 1 character ,assume each line containes key value pair seperated with spaces and not containing whitespaces
input=input.Replace("\r\n","\n");
string[] lines=input.Split('\n');
//break to categories and find largest number at each
foreach(line in lines)
{
string parts[]=line.Split(' ');
string key=parts[0].Trim();
int value=Convert.ToInt32(parts[1].Trim());
if (dict.ContainsKey(key))
{
dict.Add(key, value);
}
else
{
if (dict[key]<value)
{
dict[key]=value;
}
}
}
//do somethig with dict