Find The Maximum Value Of A DataTable?
Jun 20, 2012
I have been very stumped by this one. I have a fairly large (~1500 x ~1000) DataTable of positive and negative integers only that I acquired from a .csv file. For my program, I need to find the maximum value of the entire table, not just in a single row or column. Optimally, the code would be short and sweet, but that's not always the case ;).
The name of my DataTable is BeamMap and I am trying to return a value of MaxValue (already declared as an integer). I can post the code I have for creating the DataTable upon request.
Extra Credit: (not really)
Is there a way to quickly find the location (ie., row,column) of said maximum value? So far, all of the examples I've seen check cell by cell for a predetermined value, which is rather inefficient for the number of data points that I have.
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Jun 22, 2010
SqlServer Table1 has data as follows
Sno-------date
1------01/01/2010
8------01/01/2010
1------02/01/2010
[Code]....
1) I want to display the SMALLEST Date into textbox1 which is 01/01/2010
2) I want to display the BIGGEST Date into textbox2 which is 18/01/2010
3) I want to display the BIGGEST SNO against date 18/01/2010 into textbox3 which is 9
4) I want to display total records against date 18/01/2010 into textbox4 which is 3
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Jan 20, 2010
SqlServer Table1 has data as follows
Sno-------date
1------01/01/2010
8------01/01/2010
1------02/01/2010
5------02/01/2010
2------18/01/2010
9------18/01/2010
3------18/01/2010
1------03/01/2010
6------03/01/2010
My questions are:
1) I want to display the SMALLEST Date into textbox1 which is 01/01/2010
2) I want to display the BIGGEST Date into textbox2 which is 18/01/2010
3) I want to display the BIGGEST SNO against date 18/01/2010 into textbox3 which is 9
4) I want to display total records against date 18/01/2010 into textbox4 which is 3
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Oct 11, 2011
i am working on this exercise where i have to find suburbs with minimum and maximum percentage POS (public open space).i manage to get the minimum and maximum but i need a way to allow for two or more suburbs with same minimum or maximum..for example three subrubs ( suburb A, suburb B, and suburb C) all has same POS of 2%, then i need to list the three in the list box as minimum with subrub name(from my code i can get only one) with the maximum values as well( allow two or more suburbs with same maximum in a similar way)..below is the code.. i have removed some codes to make it read easy whi are not relevant.. i got POS percentage correct and i wanna start from there..
For intSuburb = 1 To pFClass1.FeatureCount(Nothing)
'SOME CODE HERE(this bit is long and is not relevant)..............
dblPOSPercent = CDbl(Format$(((dblSumPOSArea / dblSuburbArea) * 100), "###.#0"))[code]......
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Dec 28, 2011
I've got two data tables with store numbers. I need to find out what store numbers are in one data table that arent in another.say one table A might look like:
34, 35, 39
the other table B may be
34, 35, 39, 45
I need to find the 45 If I use nested For Next I can get matches but anything not a match would show up not just the 45 value as the next progresses.
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Feb 6, 2012
Is it possible to get the row index of a DataTable so that you can access the previous and next row? For example I have a DataTable that contains two columns ChapterTitle and PageURL. This is for a table of contents of a book. ChapterTitle is the chapter name and PageURL is an HTML page that contains the chapter (chaptername.html). When going into one chapter of the book I want to be able to tell which is the next and previous chapter.
After finding the chapter that I'm currently in how can get the next and previous rows?
ChapterTable.Select("PageURL = '" & PageURL& "'")
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Feb 14, 2012
I have 2 datatable with same structure :
table1=Column1,Column2,Column3
table2=Column1,Column2,Column3
I want to find same row in table 1 and table 2.
Sample:
Table1:
column1 | column2 | column3
------------------------------
AAA | BBB | CCCC
BBB | BBB | CCCC
CCC | BBB | CCCC
Table2:
column1 | column2 | column3
------------------------------
AAA | BBB | CCCC
BBB | BBB | CCCC
CCD | BBB | CCCC
It will return table with contain like this :
column1 | column2 | column3
------------------------------
AAA | BBB | CCCC
BBB | BBB | CCCC
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Jul 10, 2009
I want to compare each row in Table1 with Table2 and also all the columns in each row.I want to do the following1. Get Row1 from Table1. Check if the same row is present in Table22.f Row1 is present ,Check every column in Row1 with corresponding columns of that Row in Table23. Bind Table1 to a Grid. Highlight the changed cells in Red.
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Nov 25, 2011
Dim datatable_default_view As DataTable = DataTable.DefaultView.ToTable
Dim servicenumber As String = datatable_default_view.Rows.Item(e.RowIndex)("Service Number").ToString
If datatable.PrimaryKey.Length = 0 Then
Dim keys(0) As DataColumn
keys(0) = datatable.Columns("Service Number")
datatable.PrimaryKey = keys
End If
Dim datarow_edited As DataRow = datatable.Rows.Find(servicenumber)
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Jan 7, 2012
I have a Dynamic DataTable Created at runtime. The Setup is like so
Id | Name | Age
-----------------
3 | Mike | 21
6 | John | 43
8 | Sara | 34
What I am trying to do is come up with a linq statement I could use to find and update specific rows.
Such as a statement to change AGE to '33' WHERE ID = '3'
My code So far is:
-[VB.NET]-
Dim MyRow As DataRow = From column In MyTable.Rows Where column("Id") = 3
MyRow(0)("Age") = 33
But this is not updating my DataTable entry.
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Mar 1, 2012
Dim datatable_default_view As DataTable = _datatable.DefaultView.ToTable
Dim servicenumber As String = datatable_default_view.Rows.Item(e.RowIndex)("Service Number").ToString
'gets the service number of the selected row[code]....
I've put this code under the DatagridView_CellEndEdit event
The Problem: The 'data_row edited' variable doesn't get initialized when exiting the cell in edit mode using the keyboard (ie: pressing the down/up arrow).If I use the mouse it works as expected. Why is this ?
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Sep 27, 2010
When i load my database i load it into a DataSet.When i search the database i load the results in to a DataTable.I want to find what index a search result has in the DataSet.When navigating the dataset i can use this code to get the index ds.Tables"Filmer").Rows.IndexOf(ds.Tables ("Filmer"). Rows(inc))But i can't make i get the dataset index of a search result from the DataTable.I thought that i could use the same code when navigating the DataTable, but it only returns.
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Aug 5, 2011
I want to find a particular ID in a DataTable, I am using a DataView to filter the results, but how do I know which row in the original table the filter view corresponds to? Any ideas? In know I could use LINQ but I don't think this would help either?
[Code]...
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May 8, 2009
I am converting DataTables to a generic list and need a quick and easy way to implement a Find function. It seems I am going to have to use a Predicate. Upon further investigation, I still can't seem to re-create the functionality. Private Function ByKey(ByVal Instance As MyClass) As Boolean Return Instance.Key = "I NEED THIS COMPARISON TO BE DYNAMIC!" End Function
Dim Blah As MyClass = MyList.Find(AddressOf ByKey) But I have no way to pass in a key variable to this predicate to do the comparison, as I used to do with DataTable..Dim MyRow as DataRow = MyTable.Rows.Find(KeyVariable) How can I setup a predicate delegate function in VB.NET to accomplish this?
Do not recommend LINQ or lambdas because this is question is regarding .NET version 2.0.
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May 7, 2010
How can I query a DataTable to find all of the unique values in a column? SQL has the 'unique' or 'distinct' keywords, but I dont know how to do this against a DataTable.
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Apr 27, 2011
having a couple of issues with this and i don't really know how to fix this
vb.net
Imports System.Data.OleDb
Public Class Form1
Dim cn As OleDbConnection
[Code]....
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Jun 21, 2012
I am trying to program a noise reduction algorithm that works with a set of datapoints in a VB.NET DataTable after being helped with my other question. Basically, I want to take two integers, a coordinate value (yCoord for example) and a threshold smoothing value (NoiseThresh), and take the average of the values in the range of (yCoord - NoiseThresh, yCoord + NoiseThresh) and store that number into an array. I'd repeat that process for each column (in this example) and end up with a one-dimensional array of average values. My questions are:
1) Did anything I just say make any sense ;), and
2) Can anyone help me with the code? I've got very little experience working with databases.
[Code]...
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Dec 15, 2011
I have a bound datagrid which I fill from various search options that are available to the end user.Currently I have one of the columns (status) set as a DataGridViewComboBoxColumn with a collection of two items. 'Open' and 'Closed'When the I select for example 'Closed' and hit the 'Update' button an exception is passed with the caption'Update unable to find TableMapping['Tracker'] or DataTable 'Tracker''I have been looking at hope the mapping works for the last 3 hours but getting nowhere fast and I really need to get this project completed by the end of the week.The bound controls are:
Binding Source = BS
Data Member = Tracker
Data Source = TrackerDataSet
[code]...
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Sep 26, 2008
An unhandled exception of type 'System.InvalidOperationException' occurred in system.windows.forms.dllerror in line: dbAdp.Update(dbDset) in btnSave_Click, (elseif editflag = true) blockdescription: Update unable to find TableMapping['Table'] or DataTable 'Table'I was also wondering if I could simply use the ExecuteNonQuery for the delete statement, but since I've placed my data in a datarow, I'm not sure if i can actually use it. Any thoughts on this? Btw, this is my first time using a datarow, and I've recently been studying how to use ADO.net.
dr = dbDset.Tables(0).Rows(CurIndex)
dr.Delete()
dbAdp.Update(dbDset.Tables("addresses"))
[code].....
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Nov 20, 2010
If want to do a DataView.Find on a DataTable that is already 'ORDERED' by the Column I am seaching, so a DataView.SORT should not be necessary, but it throws an Exception if I don't give a .sort command before the .find command. Is there any way to avoid this apparant duplication ? and speed up the search time. Its a very large table - 1 million rows. I am using VB 2010
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Jul 21, 2010
How do i search a dataset or datatable for a record by entering 3 values in the search. If the row exists, I want to amend some of the data in that row?
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Nov 21, 2008
I'm attempting to invoke with parameters:[code]Value of '415' is not valid for 'Value'. 'Value' should be between 'minimum' and 'maximum'.Parameter name: Value..What does this mean? Is there a way around it?
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Apr 4, 2011
how can i get the maximum number in visual basic
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Jul 24, 2011
I'm trying to get the maximum value of two numbers.I want my variable z to be equal to the maximum between x and y
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Dec 10, 2009
I created a new control. When the user changes the font, I don't want the user to change the font past font size 14. If the user changes the font past 14, the font should reset to 14.
[code]...
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Aug 18, 2011
I am trying to display value of the field ("UserID") for every row exists in datatable to checkboxlist(make the checkboxlist item selected).
I used for loop, but only the field value from last row of RoleUsers table is selected in the checkboxlist.
Here is my code
Private Sub DisplayRoleUser()
Dim conn As SqlConnection
Dim cmd As SqlCommand
[Code].....
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Mar 15, 2010
I have a datatable and I apply a filter to the defaultview.rowfilter property of that datatable. If I then loop through the rows collection of the datatable, will I only be able to see those rows that the filter applies to, or will it loop through all the rows?
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Apr 21, 2010
I am working on a project that takes an xml schema and xml data files and places them into a DataTable, the 2 files are generated from a working table that i have written to disk. I wish to load these 2 files into a DataTable. Here is What i have
vb.net
Friend Function CreateTable(ByVal tableName As String) As Boolean
Dim table As New DataTable(tableName)
table.ReadXmlSchema(tableName & ".xsd")
[code]....
this however produces the following error on line 3
Quote:
System.ArgumentException was unhandled Message=DataTable 'get_item_list' does not match to any DataTable in source.
get_item_list is the parameter passed into this function (tableName)
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May 20, 2011
I have a datagridview bound to a datatable setting its datasource property to the datatable. I would like to have a child form that contains a list of columns associated with the datatable that contains a checkbox that will allow the user to hide and show the columns ( I do not know the best control to use here) (I assume this is the easy part as All i need to do is loop through each of the datatable's columns to get the column name)
now I would like save these visible columns on some event like form_closing so that the next time the user opens the form up it will remember the settings
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Apr 16, 2012
I came across a problem with using a BindingSource as my DataGridViews.DataSource. Whenever I applied a filter to a column in the BindingSource and the user makes changes that don't match the column filter the DataGridViewRows would automatically disappear. A similar thing would happen when applying a Sort to a column. If the user made any changes the DridGirdViewRows would automatically sort causing rows to be moved around. This was not ideal for my application and there isn't anyway to stop this from happening with the BindingSource.
To correct this issue I have to use subsets of data. I use a DataView to apply the filter and sort to the main DataTable, which creates the subset DataTable.The problem is when I use the DataView.ToTable method I loose the Primary Key and RowError information. So I have to reapply this information everytime the user filters or sorts the DataGridView.Is there a better way to get a subset DataTable?[code]...
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