I want to read a csv file and store the values in a correct way in dictionaries.
using (var reader = new StreamReader(#"CSV_testdaten.csv"))
{
while (!reader.EndOfStream)
{
string new_line;
while ((new_line = reader.ReadLine()) != null)
{
var values = new_line.Split(",");
g.add_vertex(values[0], new Dictionary<string, int>() { { values[1], Int32.Parse(values[2]) } });
}
}
}
the add_vertex function looks like this:
Dictionary<string, Dictionary<string, int>> vertices = new Dictionary<string, Dictionary<string, int>>();
public void add_vertex(string name, Dictionary<string, int> edges)
{
vertices[name] = edges;
}
The csv file looks like this:
there are multiple lines with the same values[0] (e.g. values[0] is "0") and instead of overwriting the existing dictionary, it should be added to the dictionary which already exists with values[0] = 0. like this:
g.add_vertex("0", new Dictionary<string, int>() { { "1", 731 } ,
{ "2", 1623 } , { "3" , 1813 } , { "4" , 2286 } , { "5" , 2358 } ,
{ "6" , 1 } , ... });
I want to add all values which have the same ID (in the first column of the csv file) to one dictionary with this ID. But I'm not sure how to do this. Can anybody help?
When we have complex data and we want to query them, Linq can be very helpful:
var records = File
.ReadLines(#"CSV_testdaten.csv")
.Where(line => !string.IsNullOrWhiteSpace(line)) // to be on the safe side
.Select(line => line.Split(','))
.Select(items => new {
vertex = items[0],
key = items[1],
value = int.Parse(items[2])
})
.GroupBy(item => item.vertex)
.Select(chunk => new {
vertex = chunk.Key,
dict = chunk.ToDictionary(item => item.key, item => item.value)
});
foreach (var record in records)
g.add_vertex(record.vertex, record.dict);
Does this work for you?
vertices =
File
.ReadLines(#"CSV_testdaten.csv")
.Select(x => x.Split(','))
.Select(x => new { vertex = x[0], name = x[1], value = int.Parse(x[2]) })
.GroupBy(x => x.vertex)
.ToDictionary(x => x.Key, x => x.ToDictionary(y => y.name, y => y.value));
You can split your code in two parts. First will read csv lines:
public static IEnumerable<(string, string, string)> ReadCsvLines()
{
using (var reader = new StreamReader(#"CSV_testdaten.csv"))
{
while (!reader.EndOfStream)
{
string newLine;
while ((newLine = reader.ReadLine()) != null)
{
var values = newLine.Split(',');
yield return (values[0], values[1], values[2]);
}
}
}
}
and second will add those lines to dictionary:
var result = ReadCsvLines()
.ToArray()
.GroupBy(x => x.Item1)
.ToDictionary(x => x.Key, x => x.ToDictionary(t => t.Item2, t => int.Parse(t.Item3)));
With your input result would be:
Related
I'm attempting to intersect a list with a dictionary, which works perfectly:
public static IDictionary<string, string> GetValues(IReadOnlyList<string> keys, IHeaderDictionary headers)
{
return keys.Intersect(headers.Keys)
.Select(k => new KeyValuePair<string, string>(k, headers[k]))
.ToDictionary(p => p.Key, p => p.Value);
}
The usage of the above method would be something like this:
[TestMethod]
public void GetValues_returns_dictionary_of_header_values()
{
var headers = new List<string> { { "trackingId" }, { "SourceParty" }, { "DestinationParty" } };
var trackingIdValue = "thisismytrackingid";
var sourcePartyValue = "thisismysourceparty";
var destinationPartyValue = "thisismydestinationparty";
var requestHeaders = new HeaderDictionary
{
{"trackingId", new Microsoft.Extensions.Primitives.StringValues(trackingIdValue) },
{"SourceParty", new Microsoft.Extensions.Primitives.StringValues(sourcePartyValue) },
{"DestinationParty", new Microsoft.Extensions.Primitives.StringValues(destinationPartyValue) },
{"randomHeader", new Microsoft.Extensions.Primitives.StringValues("dontcare") }
};
var headerValues = HeaderOperators.GetValues(headers, requestHeaders);
Assert.IsTrue(headerValues.ContainsKey("trackingId"));
Assert.IsTrue(headerValues.ContainsKey("SourceParty"));
Assert.IsTrue(headerValues.ContainsKey("DestinationParty"));
Assert.IsTrue(headerValues.Count == headers.Count);
}
However, rather than an intersect I would like to do a left join, where for example if I search the dictionary for a value that does not exist it would still return that key with some default value.
For example, if we input oneMoreKey:
var headers = new List<string> { { "trackingId" }, { "SourceParty" }, { "DestinationParty" }, {"oneMoreKey"} };
Then I would expect that the result of this would be something like this:
var headerValues = HeaderOperators.GetValues(headers, requestHeaders, "myDefaultValue");
Where headerValues is:
{"trackingId", "thisismytrackingid"}
{"SourceParty", "thisismysourceparty"}
{"DestinationParty", "thisismydestinationparty"}
{"oneMoreKey", "myDefaultValue"}
How do I add a default value to the intersection if one does not exist?
Based on this example: Left join on two Lists and maintain one property from the right with Linq you can also solve it with GroupJoin like this:
public static IDictionary<string, string> GetValues(IReadOnlyList<string> keys, IHeaderDictionary headers, string defaultValue)
{
return keys.GroupJoin(headers, key => key, header => header.Key, (key, header) => new { key, header })
.SelectMany(x => x.header.DefaultIfEmpty(), (x, header) => new { x.key, header.Value })
.Select(x => new KeyValuePair<string, string>(x.key, x.Value))
.ToDictionary(p => p.Key, p => p.Value ?? defaultValue);
}
You could use TryGetValue when creating the new dictionary to populate it with the defaults.
public static IDictionary<string, string> GetValues(IReadOnlyList<string> keys, IHeaderDictionary headers, string defaultValue)
{
return keys.ToDictionary(k => k, k => headers.TryGetValue(k, out string val) ? val : defaultValue);
}
Try this Linq in your GetValues function:
return keys.Intersect(headers.Keys)
.Select(k => new KeyValuePair<string, string>(k, headers[k]))
.Union(keys.Where(k => !headers.Keys.Contains(k)).Select(k => new KeyValuePair<string, string>(k, "myDefaultValue")))
.ToDictionary(p => p.Key, p => p.Value);
It is doing a union with any values in the header dictionary keys that can't be found in the key list, and pairing these with the default value.
I have this structure:
private readonly Dictionary<string, Dictionary<string, int>> _storage =
new Dictionary<string, Dictionary<string, int>>();
key: Firmware(string): key: Device(string) : value CountOfUsers (int)
I need to get the total of users for each device, but I really don't know how to do it with LINQ. Already tried a lot of variants. Please, help!
For now, I just use a whole function for it
private XlsRow2 GetTotalPerDevice(Dictionary<string, Dictionary<string, int>> storage)
{
XlsRow2 totalPerDeviceRow = new XlsRow2();
totalPerDeviceRow._Name = "Grand Total";
totalPerDeviceRow.UseBorders = true;
foreach (var deviceModel in _allDeviceModels)
{
foreach (var firmware in storage)
{
foreach (var device in firmware.Value)
{
var countOfUsers = 0;
if (deviceModel == device.Key)
{
countOfUsers += device.Value;
if (!_totalsPerDevice.ContainsKey(deviceModel))
{
_totalsPerDevice.Add(deviceModel, countOfUsers);
}
else
{
_totalsPerDevice[deviceModel] += countOfUsers;
}
}
}
}
}
foreach (var deviceModel in _allDeviceModels)
{
if (_totalsPerDevice.ContainsKey(deviceModel))
{
totalPerDeviceRow._AddColumn(_totalsPerDevice.First(k => k.Key == deviceModel.ToString()).Value.ToString());
}
else
{
totalPerDeviceRow._AddColumn("");
}
}
return totalPerDeviceRow;
}
Something like this for example?
var result = _storage.SelectMany(x => x.Value)
.GroupBy(x => x.Key)
.Select(x => new { Device = x.Key, Total = x.Sum(y => y.Value) });
Since the keys for the data that you would like to aggregate is in the second-level dictionary, a good first step would be to dump all key-value pairs from inner dictionaries into a flat sequence. After that all you need is to aggregate the counts, like this:
var res = _storage
.SelectMany(d => d.Value)
.GroupBy(kvp => kvp.Key)
.ToDictionary(g => g.Key, g => g.Sum(kvp => kvp.Value));
A Dictionary implements IEnumerable<KeyValuePair<TKey,TValue> which means you can use LINQ on it. In this case you have a dictionary of dictionaries and need to group by the second level key. To do that, you need to flatten the dictionaries, something that can be done with SelectMany
_storage.Selectmany(pair=>pair.Value);
Once you have the leaf-level entries, you can group by their keys:
_storage.Selectmany(pair=>pair.Value)
.GroupBy(leaf=>leaf.Key);
And calculate the sum per group:
var totals=_storage.SelectMany(pair=>pair.Value)
.GroupBy(leaf=>leaf.Key)
.Select(grp=>new {
Device = grp.Key,
TotalUsers =grp.Sum(leaf=>leaf.Value)
});
The equivalent query is rather cleaner:
var totals2 = from frm in _storage
from dev in frm.Value
group dev by dev.Key into grp
select new {
Device = grp.Key,
Total=grp.Sum(leaf=>leaf.Value)
};
Given the following dictionary:
var _storage = new Dictionary<string, Dictionary<string, int>> {
["Frm1"]=new Dictionary<string, int> {
["Device1"]=4,
["Device2"]=5
},
["Frm2"]=new Dictionary<string, int> {
["Device1"]=41,
["Device3"]=5
}
};
Both queries return the same values
foreach(var total in totals)
{
Console.WriteLine ($"{total.Device} = {total.Total}");
}
------------------
Device1 = 45
Device2 = 5
Device3 = 5
You can do this like:
Dictionary<string, Dictionary<string, int>> _storage = new Dictionary<string, Dictionary<string, int>>();
Dictionary<string, int> x = new Dictionary<string, int>();
x.Add("x", 2);
x.Add("z", 2);
x.Add("y", 2);
_storage.Add("x", x);
_storage.Add("z", x);
_storage.Add("y", x);
var b = _storage.SelectMany(keyValuePair => keyValuePair.Value)
.GroupBy(keyValuePair => keyValuePair.Key)
.ToDictionary(valuePairs => valuePairs.Key, grouping => grouping.Sum(kvp => kvp.Value));
result will be like:
Following on from this post is it possible to create a new list of the duplicate records found (and excluded) in the merge? I want to let the user know which records were excluded. The code I have is working in that it is correctly merging the data and excluding any duplicate keys, but I want to be able to show the keys excluded after the merge.
var fileLocation = #"D:\TFS2010-UK\Merge_Text\PM.INX";
var fileContents =
File.ReadLines(FileLocation, Encoding.Default)
.Select(line => line.Split(','))
.ToDictionary(line => line[0].Replace("\"", ""), line => line[1] + ',' + line[2] + ',' + line[3]);
// define an array of items to be added...
var newContent = new Dictionary<string, string>
{
{ "XYZ789", "\"XYZ789\",1,123.789" },
{ "GHI456", "\"GHI456\",2,123.456" },
{ "ABC123", "\"ABC123\",1,123.123" }
};
var uniqueElements = fileContents.Concat(newContent.Where(kvp => !fileContents.ContainsKey(kvp.Key)))
.OrderBy(x => x.Key)
.ToDictionary(y => y.Key, z => z.Value);
// append new lines to the existing file...
using (var writer = new StreamWriter(fileLocation))
{
// loop through the data to be written...
foreach (var pair in uniqueElements)
{
// and write it to the file...
writer.WriteLine("\"{0}\",{1}", pair.Key, pair.Value);
}
}
Many thanks. Martin
var removedKeys = newContent.Where(kvp => fileContents.ContainsKey(kvp.Key))
.Select(kvp => kvp.Key);
Simply select the keys in newContent that are already contained in fileContents.
I have a List of String like
List<String> MyList=new List<String>{"A","B"};
and a
Dictionary<String, Dictionary<String,String>> MyDict=new Dictionary<String,Dictionary<String,String>>();
which contains
Key Value
Key Value
"ONE" "A_1" "1"
"A_2" "2"
"X_1" "3"
"X_2" "4"
"B_1" "5"
"TWO" "Y_1" "1"
"B_9" "2"
"A_4" "3"
"B_2" "6"
"X_3" "7"
I need to merge the the list and Dictionary into a new Dictionary
Dictionary<String,String> ResultDict = new Dictionary<String,String>()
The resulting dictionary contains
Key Value
"A_1" "1"
"A_2" "2"
"B_1" "5"
"A_4" "3"
"B_2" "6"
"X_2" "4"
"X_3" "7"
Merge rule
First add the items which has a substring equals to any item in the list.
Then Merge the items in the "MyDict" so the result should not contain duplicate keys as well as duplicate values.
Here is my source code.
Dictionary<String, String> ResultDict = new Dictionary<string, string>();
List<String> TempList = new List<string>(MyDict.Keys);
for (int i = 0; i < TempList.Count; i++)
{
ResultDict = ResultDict.Concat(MyDict[TempList[i]])
.Where(TEMP => MyList.Contains(TEMP.Key.Contains('_') == true ? TEMP.Key.Substring(0, TEMP.Key.LastIndexOf('_'))
: TEMP.Key.Trim()))
.ToLookup(TEMP => TEMP.Key, TEMP => TEMP.Value)
.ToDictionary(TEMP => TEMP.Key, TEMP => TEMP.First())
.GroupBy(pair => pair.Value)
.Select(group => group.First())
.ToDictionary(pair => pair.Key, pair => pair.Value); }
for (int i = 0; i < TempList.Count; i++)
{
ResultDict = ResultDict.Concat(MyDict[TempList[i]])
.ToLookup(TEMP => TEMP.Key, TEMP => TEMP.Value)
.ToDictionary(TEMP => TEMP.Key, TEMP => TEMP.First())
.GroupBy(pair => pair.Value)
.Select(group => group.First())
.ToDictionary(pair => pair.Key, pair => pair.Value);
}
its working fine, but I need to eliminate the two for loops or at least one
(Any way to do this using LINQ or LAMBDA expression)
Here's one way you could do it with LINQ and lambdas, as requested:
var keysFromList = new HashSet<string>(MyList);
var results =
MyDict.Values
.SelectMany(x => x)
.OrderBy(x => {
int i = x.Key.LastIndexOf('_');
string k = (i < 0) ? x.Key.Trim()
: x.Key.Substring(0, i);
return keysFromList.Contains(k) ? 0 : 1;
})
.Aggregate(new {
Results = new Dictionary<string, string>(),
Values = new HashSet<string>()
},
(a, x) => {
if (!a.Results.ContainsKey(x.Key)
&& !a.Values.Contains(x.Value))
{
a.Results.Add(x.Key, x.Value);
a.Values.Add(x.Value);
}
return a;
},
a => a.Results);
Loop wise this code is simpler, but not Linq:
public static Dictionary<string, string> Test()
{
int initcount = _myDict.Sum(keyValuePair => keyValuePair.Value.Count);
var usedValues = new Dictionary<string, string>(initcount); //reverse val/key
var result = new Dictionary<string, string>(initcount);
foreach (KeyValuePair<string, Dictionary<string, string>> internalDicts in _myDict)
{
foreach (KeyValuePair<string, string> valuePair in internalDicts.Value)
{
bool add = false;
if (KeyInList(_myList, valuePair.Key))
{
string removeKey;
if (usedValues.TryGetValue(valuePair.Value, out removeKey))
{
if (KeyInList(_myList, removeKey)) continue;
result.Remove(removeKey);
}
usedValues.Remove(valuePair.Value);
add = true;
}
if (!add && usedValues.ContainsKey(valuePair.Value)) continue;
result[valuePair.Key] = valuePair.Value;
usedValues[valuePair.Value] = valuePair.Key;
}
}
return result;
}
private static bool KeyInList(List<string> myList, string subKey)
{
string key = subKey.Substring(0, subKey.LastIndexOf('_'));
return myList.Contains(key);
}
I am trying to create a dictionary from 2 lists where one list contains keys and one list contains values. I can do it using for loop but I am trying to find if there is a way of doing it using LINQ.
Sample code will be helpfull. Thanks!!!!
In .NET4 you could use the built-in Zip method to merge the two sequences, followed by a ToDictionary call:
var keys = new List<int> { 1, 2, 3 };
var values = new List<string> { "one", "two", "three" };
var dictionary = keys.Zip(values, (k, v) => new { Key = k, Value = v })
.ToDictionary(x => x.Key, x => x.Value);
List<string> keys = new List<string>();
List<string> values = new List<string>();
Dictionary<string, string> dict = keys.ToDictionary(x => x, x => values[keys.IndexOf(x)]);
This of course assumes that the length of each list is the same and that the keys are unique.
UPDATE: This answer is far more efficient and should be used for lists of non-trivial size.
You can include the index in a Select expression to make this efficient:
var a = new List<string>() { "A", "B", "C" };
var b = new List<string>() { "1", "2", "3" };
var c = a.Select((x, i) => new {key = x, value = b[i]}).ToDictionary(e => e.key, e => e.value );
foreach (var d in c)
Console.WriteLine(d.Key + " = " + d.Value);
Console.ReadKey();
var dic = keys.Zip(values, (k, v) => new { k, v })
.ToDictionary(x => x.k, x => x.v);
You can use this code and working perfectly.
C# Code:
var keys = new List<string> { "Kalu", "Kishan", "Gourav" };
var values = new List<string> { "Singh", "Paneri", "Jain" };
Dictionary<string, string> dictionary = new Dictionary<string, string>();
for (int i = 0; i < keys.Count; i++)
{
dictionary.Add(keys[i].ToString(), values[i].ToString());
}
foreach (var data in dictionary)
{
Console.WriteLine("{0} {1}", data.Key, data.Value);
}
Console.ReadLine();
Output Screen: