I need to fill an array with 60 values type int, and I have the values inside a DbSet in the database.
Without making a loop, is there a way I can conver this List to a Int[].
The value is in a property called temperature
public void SetLineChartData()
{
//Suppose we have a list of 60 items.
using (ZigBeeContext db = new ZigBeeContext())
{
var lista = (from p in db.Medidas
select new Medida
{
Fecha = p.FechaHora
}).ToList();
}
lineChartData = new int[60];
lineChartData[0] = RandomNumberGenerator.randomScalingFactor();
hora[0] = DateTime.Now.ToShortTimeString();
lineChartData[1] = RandomNumberGenerator.randomScalingFactor();
hora[1] = DateTime.Now.ToShortTimeString();
lineChartData[2] = RandomNumberGenerator.randomScalingFactor();
hora[2] = DateTime.Now.ToShortTimeString();
lineChartData[3] = RandomNumberGenerator.randomScalingFactor();
hora[3] = DateTime.Now.ToShortTimeString();
lineChartData[4] = RandomNumberGenerator.randomScalingFactor();
hora[4] = DateTime.Now.ToShortTimeString();
lineChartData[5] = RandomNumberGenerator.randomScalingFactor();
hora[5] = DateTime.Now.ToShortTimeString();
lineChartData[6] = RandomNumberGenerator.randomScalingFactor();
hora[6] = DateTime.Now.ToShortTimeString();
//colorString = "rgba(" + RandomNumberGenerator.randomColorFactor() + "," + RandomNumberGenerator.randomColorFactor() + "," + RandomNumberGenerator.randomColorFactor() + ",.3)";
}
I need to fill an array with 60 values type int, and I have the values inside a DbSet in the database.
Without making a loop, is there a way I can conver this List to a Int[]. The value is in a property called temperature
Not sure what you mean by "Without making a loop" as many functions will perform loops even if they don't look like it.
If I understand what you are trying to do, then maybe something like this:
int[] myArray = lista.Select(x => x.temperature).ToArray();
LINQ can provide what you are asking for:
var arr = lista.Select(i => i.Fecha).ToArray();
With Linq you can do that like this :
List<MyObject> lst = new List<MyObject>(); // fake dbSet can be Queryable
int[] toto = lst.Take(60).Select(item => item.MyInt).ToArray();
private class MyObject
{
public int MyInt { get; set; }
}
Just use Linq:
public void SetLineChartData()
{
int[] yourIntArray; // your int array
//Suppose we have a list of 60 items.
using (ZigBeeContext db = new ZigBeeContext())
{
var lista = (from p in db.Medidas
select new Medida
{
Fecha = p.FechaHora,
}).ToList();
// here is how you can do that
yourIntArray = lista.Select(x =>
x.FechaHora //i think that's property that you need to be in int array
).ToArray();
}
}
If FechaHora is not an int already, and you want to cast it, you could do this...
int[] lista = db.Medidas.Select(p => p.FechaHora).Cast<int>().ToArray();
Related
I'm looking to create a method that loops through an list and replaces with matched values with a new value. I have something working below but it really doesnt follow the DRY principal and looks ugly.
How could I create a dictionary of value pairs that would hold my data of values to match and replace?
var match = acreData.data;
foreach(var i in match)
{
if (i.county_name == "DE KALB")
{
i.county_name = "DEKALB";
}
if (i.county_name == "DU PAGE")
{
i.county_name = "DUPAGE";
}
}
In your question, you can try to use linq and Replace to make it.
var match = acreData.data.ToList();
match.ForEach(x =>
x.county_name = x.county_name.Replace(" ", "")
);
or you can try to create a mapper table to let your data mapper with your value. as #user2864740 say.
Dictionary<string, string> dict = new Dictionary<string, string>();
dict.Add("DE KALB", "DEKALB");
dict.Add("DU PAGE", "DUPAGE");
var match = acreData.data;
string val = string.Empty;
foreach (var i in match)
{
if (dict.TryGetValue(i.county_name, out val))
i.county_name = val;
}
If this were my problem and it is possible a county could have more than one common misspelling I would create a class to hold the correct name and the common misspellings. The you could easily determine if the misspelling exists and correct if. Something like this:
public class County
{
public string CountyName { get; set; }
public List<string> CommonMisspellings { get; set; }
public County()
{
CommonMisspellings = new List<string>();
}
}
Usage:
//most likely populate from db
var counties = new List<County>();
var dekalb = new County { CountyName = "DEKALB" };
dekalb.CommonMisspellings.Add("DE KALB");
dekalb.CommonMisspellings.Add("DE_KALB");
var test = "DE KALB";
if (counties.Any(c => c.CommonMisspellings.Contains(test)))
{
test = counties.First(c => c.CommonMisspellings.Contains(test)).CountyName;
}
If you are simply replacing all words in a list containing space without space, then can use below:
var newList = match.ConvertAll(word => word.Replace(" ", ""));
ConvertAll returns a new list.
Also, I suggest not to use variable names like i, j, k etc..but use temp etc.
Sample code below:
var oldList = new List<string> {"DE KALB", "DE PAGE"};
var newList = oldList.ConvertAll(word => word.Replace(" ", ""));
We can try removing all the characters but letters and apostroph (Cote d'Ivoire has it)
...
i.country_name = String.Concat(i.country_name
.Where(c => char.IsLetter(c) || c == '\''));
...
I made a comment under answer of #Kevin and it seems it needs further explanation. Sequential searching in list does not scale well and unfortunately for Kevin, that is not my opinion, asymptotic computational complexity is math. While searching in dictionary is more or less O(1), searching in list is O(n). To show a practical impact for solution with 100 countries with 100 misspellings each, lets make a test
public class Country
{
public string CountryName { get; set; }
public List<string> CommonMisspellings { get; set; }
public Country()
{
CommonMisspellings = new List<string>();
}
}
static void Main()
{
var counties = new List<Country>();
Dictionary<string, string> dict = new Dictionary<string, string>();
Random rnd = new Random();
List<string> allCountryNames = new List<string>();
List<string> allMissNames = new List<string>();
for (int state = 0; state < 100; ++state)
{
string countryName = state.ToString() + rnd.NextDouble();
allCountryNames.Add(countryName);
var country = new Country { CountryName = countryName };
counties.Add(country);
for (int miss = 0; miss < 100; ++miss)
{
string missname = countryName + miss;
allMissNames.Add(missname);
country.CommonMisspellings.Add(missname);
dict.Add(missname, countryName);
}
}
List<string> testNames = new List<string>();
for (int i = 0; i < 100000; ++i)
{
if (rnd.Next(20) == 1)
{
testNames.Add(allMissNames[rnd.Next(allMissNames.Count)]);
}
else
{
testNames.Add(allCountryNames[rnd.Next(allCountryNames.Count)]);
}
}
System.Diagnostics.Stopwatch st = new System.Diagnostics.Stopwatch();
st.Start();
List<string> repairs = new List<string>();
foreach (var test in testNames)
{
if (counties.Any(c => c.CommonMisspellings.Contains(test)))
{
repairs.Add(counties.First(c => c.CommonMisspellings.Contains(test)).CountryName);
}
}
st.Stop();
Console.WriteLine("List approach: " + st.ElapsedMilliseconds.ToString() + "ms");
st = new System.Diagnostics.Stopwatch();
st.Start();
List<string> repairsDict = new List<string>();
foreach (var test in testNames)
{
if (dict.TryGetValue(test, out var val))
{
repairsDict.Add(val);
}
}
st.Stop();
Console.WriteLine("Dict approach: " + st.ElapsedMilliseconds.ToString() + "ms");
Console.WriteLine("Repaired count: " + repairs.Count
+ ", check " + (repairs.SequenceEqual(repairsDict) ? "OK" : "ERROR"));
Console.ReadLine();
}
And the result is
List approach: 7264ms
Dict approach: 4ms
Repaired count: 4968, check OK
List approach is about 1800x slower, actually more the thousand times slower in this case. The results are as expected. If that is a problem is another question, it depends on concrete usage pattern in concrete application and is out of scope of this post.
In the following code , rating in generating error
string[] allLines = File.ReadAllLines(#"Ratings.csv");
var parsed = from line in allLines
let row = line.Split(';')
select new
{
UserId = row[0],
ItemId = row[1],
rating = row[3]
};
var Rating = parsed.Select(x => new AddRating (x.UserId, x.ItemId,x.rating));
client.Send(new Batch(Rating));
var detailViews = parsed.Select(x => new AddDetailView(x.UserId, x.ItemId,x.rating ));
The exception is telling you what the issue is. Your constructor is expecting doubles, and you're passing it strings. In order to fix it, you've gotta parse your string inputs into doubles.
The way your code is written, you'll have to change the way you're using the .Select statement in order to parse it in a decent error handling manner.
I'd suggest swapping the .Select for a foreach, then parsing each property, then instantiating your class.
foreach (var item in parsed)
{
double userId = 0;
double itemId = 0;
double rating = 0;
double.TryParse(item.UserId, out userId);
double.TryParse(item.ItemId, out itemId);
double.TryParse(item.rating, out rating);
var rating = new AddRating(userId, itemId, rating);
//**** do whatever you want with the new object
}
String st = "85.78";
Double db = Convert.ToDouble(st);
//Or With Error Hndler
try
{
string st = "85.78";
Double db = Convert.ToDouble(st);
}
catch (FormatException)
{
// Your error handler
}
How do I conditionally update List<object> items using LINQ, I have managed to get a way to update all items in List<object> using this syntax:
var updatedList = sourceList.Select( x => { x.PropertyA = NewValue; return x; }).ToList();
var updatedList = sourceList.Select( x => {return x = x.PropertyA == SomeValue ? x1 : x;}).ToList();
You can either project it to a new collection using the .Select, or affect the original list using the .ForEach extension method. Both are shown below, given an arbitrary condition.
class Program
{
static void Main(string[] args)
{
List<testClass> ogList = new List<testClass>();
bool testCondition = true;
//use the select to update and project to new collection
var updated =
ogList
.Select(x =>
{
if (testCondition)
x.testProp = 1;
return x;
}).ToList();
//use the foreach to update original collection
ogList.ForEach(x =>
{
if (testCondition)
x.testProp = 1;
});
}
}
public class testClass
{
public int testProp { get; set; }
}
You can use this code:
sourceList.Where(w => w.CheckProperty == valueofProperty).Select(s => {
s.PropertyA = valueofPropertyA ;
s.PropertyB = valueofPropertyB;
return s;
}).ToList();
Hope this answer will help you.
So here I creating objects of my database, list of my db_table and table.
private DB dbs = new DB();
List<tab1> lst = new List<tab1>();
tab1 tabobj = new tab1();
here you will get the list of data in your table
lst = dbs.tab1.ToList();
````````````
updating the table
```````````
tabobj.c1 = "value";
tabobj.c2 = "value";
adding updated columns to table
dbs.tab1.Add(tabobj);
save changes here
dbs.SaveChanges();
data of updated table
lst = dbs.tab1.ToList();
I receive the above error message when performing a unit test on a method. I know where the problem is at, I just don't know why it's not present in the dictionary.
Here is the dictionary:
var nmDict = xelem.Descendants(plantNS + "Month").ToDictionary(
k => new Tuple<int, int, string>(int.Parse(k.Ancestors(plantNS + "Year").First().Attribute("Year").Value), Int32.Parse(k.Attribute("Month1").Value), k.Ancestors(plantNS + "Report").First().Attribute("Location").Value.ToString()),
v => {
var detail = v.Descendants(plantNS + "Details").First();
return new HoursContainer
{
BaseHours = detail.Attribute("BaseHours").Value,
OvertimeHours = detail.Attribute("OvertimeHours").Value,
TotalHours = float.Parse(detail.Attribute("BaseHours").Value) + float.Parse(detail.Attribute("OvertimeHours").Value)
};
});
var mergedDict = new Dictionary<Tuple<int, int, string>, HoursContainer>();
foreach (var item in nmDict)
{
mergedDict.Add(Tuple.Create(item.Key.Item1, item.Key.Item2, "NM"), item.Value);
}
var thDict = xelem.Descendants(plantNS + "Month").ToDictionary(
k => new Tuple<int, int, string>(int.Parse(k.Ancestors(plantNS + "Year").First().Attribute("Year").Value), Int32.Parse(k.Attribute("Month1").Value), k.Ancestors(plantNS + "Report").First().Attribute("Location").Value.ToString()),
v => {
var detail = v.Descendants(plantNS + "Details").First();
return new HoursContainer
{
BaseHours = detail.Attribute("BaseHours").Value,
OvertimeHours = detail.Attribute("OvertimeHours").Value,
TotalHours = float.Parse(detail.Attribute("BaseHours").Value) + float.Parse(detail.Attribute("OvertimeHours").Value)
};
});
foreach (var item in thDict)
{
mergedDict.Add(Tuple.Create(item.Key.Item1, item.Key.Item2, "TH"), item.Value);
}
return mergedDict;
and here is the method that is being tested:
protected IList<DataResults> QueryData(HarvestTargetTimeRangeUTC ranges,
IDictionary<Tuple<int, int, string>, HoursContainer> mergedDict)
{
var startDate = new DateTime(ranges.StartTimeUTC.Year, ranges.StartTimeUTC.Month, 1);
var endDate = new DateTime(ranges.EndTimeUTC.Year, ranges.EndTimeUTC.Month, 1);
const string IndicatorName = "{6B5B57F6-A9FC-48AB-BA4C-9AB5A16F3745}";
DataResults endItem = new DataResults();
List<DataResults> ListOfResults = new List<DataResults>();
var allData =
(from vi in context.vDimIncidents
where vi.IncidentDate >= startDate.AddYears(-3) && vi.IncidentDate <= endDate
select new
{
vi.IncidentDate,
LocationName = vi.LocationCode,
GroupingName = vi.Location,
vi.ThisIncidentIs, vi.Location
});
var finalResults =
(from a in allData
group a by new { a.IncidentDate.Year, a.IncidentDate.Month, a.LocationName, a.GroupingName, a.ThisIncidentIs, a.Location }
into groupItem
select new
{
Year = String.Format("{0}", groupItem.Key.Year),
Month = String.Format("{0:00}", groupItem.Key.Month),
groupItem.Key.LocationName,
GroupingName = groupItem.Key.GroupingName,
Numerator = groupItem.Count(),
Denominator = mergedDict[Tuple.Create(groupItem.Key.Year, groupItem.Key.Month, groupItem.Key.LocationName)].TotalHours,
IndicatorName = IndicatorName,
}).ToList();
for (int counter = 0; counter < finalResults.Count; counter++)
{
var item = finalResults[counter];
endItem = new DataResults();
ListOfResults.Add(endItem);
endItem.IndicatorName = item.IndicatorName;
endItem.LocationName = item.LocationName;
endItem.Year = item.Year;
endItem.Month = item.Month;
endItem.GroupingName = item.GroupingName;
endItem.Numerator = item.Numerator;
endItem.Denominator = item.Denominator;
}
foreach(var item in mergedDict)
{
if(!ListOfResults.Exists(l=> l.Year == item.Key.Item1.ToString() && l.Month == item.Key.Item2.ToString()
&& l.LocationName == item.Key.Item3))
{
for (int counter = 0; counter < finalResults.Count; counter++)
{
var data = finalResults[counter];
endItem = new DataResults();
ListOfResults.Add(endItem);
endItem.IndicatorName = data.IndicatorName;
endItem.LocationName = item.Key.Item3;
endItem.Year = item.Key.Item1.ToString();
endItem.Month = item.Key.Item2.ToString();
endItem.GroupingName = data.GroupingName;
endItem.Numerator = 0;
endItem.Denominator = item.Value.TotalHours;
}
}
}
return ListOfResults;
}
The error occurs here:
Denominator = mergedDict[Tuple.Create(groupItem.Key.Year, groupItem.Key.Month, groupItem.Key.LocationName)].TotalHours,
I do not understand why it is not present in the key. The key consists on an int, int, string (year, month, location) and that is what I have assigned it.
I've looked at all of the other threads concerning this error message but I didn't see anything that applied to my situation.
I was unsure of what tags to put on this but from my understanding the dictionary was created with linq to xml, the query is linq to sql and it's all part of C# so I used all the tags. if this was incorrect then I apologize in advance.
The problem is with comparisons between the keys you are storing in the Dictionary and the keys you are trying to look up.
When you add something to a Dictionary or access the indexer of a Dictionary it uses the GetHashCode() method to get a hash value of the key. The hashcode for a Tuple is unique to that instance of the Tuple. This means that unless you are passing in the exact same instance of the Tuple class into the indexer, it will not find the previously stored value. Your usage of mergedDict[Tuple.Create(... creates a brand new Tuple with a different hash code than is stored in the Dictionary.
I would recommend creating your own class to use as the key and implementing GetHashCode() and the Equality methods on that class. That way the Dictionary will be able to find what you previously stored there.
More:
The reason this is confusing to a lot of people is that for something like String or Int32, String.GetHashCode() will return the same hash code for two different instances that have the same value. A more specialized class such as Tuple doesn't always work the same. The implementor of Tuple could have gotten the hash code of each input to the Tuple and added them together (or something), but running Tuple through a decompiler you can see that this is not the case.
I am trying to get data from database for Google charts in my program. I would like to create an array of anonymous type (var) instead of repeating my code over and over again:
public JsonResult GetChartData(int sID, int regionID)
{
var testPathOne = from p in _rep.GetMetricsData().GetLHDb().page_loads
where p.t_3id == sID && p.test_path_id == 1
select new { time = p.time, created_at = p.created_at };
var testPathTwo = from p in _rep.GetMetricsData().GetLHDb().page_loads
where p.t_3id == sID && p.test_path_id == 2
select new { time = p.time, created_at = p.created_at };
var tOne = testPathOne.ToArray();
var tTwo = testPathTwo.ToArray();
var name = new { test1 = tOne, test2 = tTwo };
return Json(name);
}
i know that i will need a for loop so i can go through all the test path id's instead of hard coding them like this p.test_path_id == 1, but my question is how would i make this part dynamic var name = new { test1 = tOne, test2 = tTwo };
Edit:
I apologize, I would like to do something like this:
name is an array
for loop:
testPath = query
name.Add(testPath)
I hope that makes sense
The easiest solution in this particular case would be to just give a name to the class that is currently anonymous. While there are workarounds that you can use, when you need to start working really hard to use an anonymous type you probably shouldn't be using it. It's there to make certain tasks quicker and easier; if that isn't happening then you are likely better off with a real class.
That solution would look something like this:
//Please give me a real name
public class ClassToBeRenamed
{
public DateTime Time { get; set; }
public DateTime CreatedAt { get; set; }
}
List<ClassToBeRenamed[]> myList = new List<ClassToBeRenamed[]>();
for (int i = 0; i < 10; i++)
{
myList.Add((from p in _rep.GetMetricsData().GetLHDb().page_loads
where p.t_3id == sID && p.test_path_id == i
select new ClassToBeRenamed { Time = p.time, CreatedAt = p.created_at })
.ToArray());
}
Having said all of that, it's still possible.
var myList = new[]{
from p in _rep.GetMetricsData().GetLHDb().page_loads
where p.t_3id == sID && p.test_path_id == 1
select new { time = p.time, created_at = p.created_at }.ToArray()
}.ToList();
for (int i = 2; i < 10; i++)
{
myList.Add(from p in _rep.GetMetricsData().GetLHDb().page_loads
where p.t_3id == sID && p.test_path_id == i
select new { time = p.time, created_at = p.created_at }.ToArray()
);
}
var myArray = myList.ToArray();
If it's really, really important that you have an array, and not a list, then you could call ToArray on myList at the very end. It's important that you start out with a list, and only convert it to an array at the end because Arrays have a fixed size once they are created. You can mutate their contents, but you can't make them bigger or smaller. A List on the other hand, is designed to mutate it's size over time, so it can start out with 0 or 1 items and then add items over time, which is important for us in this particular context. (It's actually useful quite often, which is why it is frequently useful to use List over arrays.)
Instead of using LINQ use foreach loops. You are more limited with LINQ.
Also define your ArrayLists at the beginning and add to them as you go.
var test1 = new ArrayList();
var test2 = new ArrayList();
foreach(PageLoad p in _rep.GetMetricsData().GetLHDb().page_loads)
{
if(p.t_3id == sID)
{
var tr = new { time = p.time, created_at = p.created_at };
switch(p.test_path_id)
{
case 1: test1.Add(tr); break;
case 2: test2.Add(tr); break;
}
}
}
return Json(new { test1, test2, });
You do not need to define the names of properties anonymous types because they default to the variable names.