Develop Reference

Magick.net check if two images are identical

I'm trying to compare two screenshots from a webpage using Magick.NET, a C# library from ImageMagick. My code looks like this:
//Adapt image a bit otherwise he'll throw an error over the whole image
newScreenshot.ColorFuzz = new Percentage(15);
//Get the difference, 1 = perfectly the same, less then 1 not.
double diff = newScreenshot.Compare(benchmarkScreenshot, new ErrorMetric(), imgDiff);
//Output the result image for comparaison
imgDiff.Write(compareResultPath);
if (diff < 0.998)
{
//Do something
}
In this case I would get values lower then 1, where I imagined 1 would be "Identical" and everything less then 1 wouldn't be. I was wrong... So the only way I could think of to check if they are as identical as possible is to lower the tolerence by lowering the value in the if-statement.
So if I have a screenshot from a website, and I adapt it I get the following values for the "diff" variable:
Identical image: 0.99842343024053205
Removing a sentence: 0.99776453647987487
Removing one letter from any word on the page: 0.99698398328761506
I'm very afraid of the fact that removing an entire sentence has a higher value then just a single letter.
I also tried with ErrorMetric.Absolute rather then new ErrorMetric(), the values that I got for the "diff" variable were:
Identical image: 1949
Removing a sentence: 766
Removing one letter from any word on the page: 75
Is there a better, more accurate way then what I'm trying to do to check if there's an actual change or not?

Formatting a string to display custom decimal values

I'm trying to format some doubles properly so that they will display properly for my uses (I'm building a statement in Devexpress, so I'm working with a lot of numbers).
Here are the basic formatting rules I'd like to have happen:
1000.2 -> 1,000.20
1000 -> 1,000
1000.22 -> 1,000.22
Is this possible using string formatting in C#? I've tried the following, but not been able to achieve my goal:
#,#.## - gives me 1,000.2 for the first value
#,#.#0 - gives me 1,000.00 for the second value
#,#.00 - gives me 1,000.00 for the second value
EDIT: Some more information. DevExpress gives me the ability to use string formatting to set up the values after they've been bound to the report. We're doing it at report time (and not at calculation time in the behind the scenes code) because we use the Sum function within the tables that DevExpress offers us. The reason we do THAT is so that we can minimize calls to our database by doing one large pull of data, then using that table over and over again in the statement and filtering based on the restrictions within.
EDIT EDIT:
Based on the feedback I've receieved here in the comments, it's not possible to perform the formatting I'd like to do with only providing a string format; I would need to insert some code either when I provide the data to the report (and then remove any and all formatting from the report) and perform all summing functions at the code level (to ensure that the sum values have the expected decimal places), or I would need to accept .00 at the end of, for example, some amount of yen (100 JPY would never be represented as 100.00 JPY, as an example).
This is a bit of an esoteric case, but it's good to know!

You can use string formatting coupled to a simple if condition. To shorten it's use, you can also make it an Extension method. It can look like this :
public static string FormatConditionnaly(this double input)
{
return input % 1 == 0 ? input.ToString("#,0") : input.ToString("#,0.00");
}
Basically, if you number does not contain any decimals (the % 1 == 0 check), you format it without decimals. If it fails the check, you add the two zeroes.
It is used like that :
const double flatNumber = 1000;
string result1 = flatNumber.FormatConditionnaly(); //1,000
const double numberWithDecimals = 1000.5;
string result2 = numberWithDecimals.FormatConditionnaly(); //1,000,50

Bit of a hack but you can give this a try:
s = String.Format("{0:N2}", 1000).Replace(".00", "");

Use the "N" format specifier as the format string when you call ToString(); See here
For example:
int intValue = 123456789;
Console.WriteLine(intValue.ToString("N2",
CultureInfo.InvariantCulture).Replace(".00", "");
You can customize group sizes etc. as needed.

Why don't you format the values before binding to DevExpress control using plain old C# (Assuming you are doing a bind, as you have not given sufficient details.)
In c# the Math.Round() should do the trick.
Example Math.Round(doubleValue,2) where the second parameter is the number of decimal places.
EDIT:
#,##0.00
I Do not have DevExpress controls to test my solution but I did find http://documentation.devexpress.com/#windowsforms/CustomDocument1498 online (not sure if you see it already).
It seems you can use the Number or Currency masks.
Also take a look at the Zero Placeholder under the custom section. based on the description, '0' is filled where the user has not supplied a value.
example: 123.4 --> 123.40

If the string that you're trying to format is in an XRTableCell of an XtraReport instance, you can handle the BeforePrint event on that cell to format its text. This event is triggered anytime that the report is rendered. Call GetCurrentColumnValue to retrieve the value that you want to format, use any of the code methods from the previous answers that will work for you, and then set that cell's text with your formatted string. Using #dweeberly's answer:
private void OnBeforePrint(object sender, PrintEventArgs e)
{
object value = this.GetCurrentColumnValue("YourField");
if (value != null)
{
yourCell.Text = String.Format("{0:N2}", value.ToString()).Replace(".00", "");
}
}

Based on the feedback I've receieved here in the comments, it's not possible to perform the formatting I'd like to do with only providing a string format; I would need to insert some code either when I provide the data to the report (and then remove any and all formatting from the report) and perform all summing functions at the code level (to ensure that the sum values have the expected decimal places), or I would need to accept .00 at the end of, for example, some amount of yen (100 JPY would never be represented as 100.00 JPY, as an example).
This is a bit of an esoteric case, but it's good to know!

string(";P") is bigger or string("-_-") is bigger?

I found very confusing when sorting a text file. Different algorithm/application produces different result, for example, on comparing two string str1=";P" and str2="-_-"
Just for your reference here gave the ASCII for each char in those string:
char(';') = 59; char('P') = 80;
char('-') = 45; char('_') = 95;
So I've tried different methods to determine which string is bigger, here is my result:
In Microsoft Office Excel Sorting command:
";P" < "-_-"
C++ std::string::compare(string &str2), i.e. str1.compare(str2)
";P" > "-_-"
C# string.CompareTo(), i.e. str1.CompareTo(str2)
";P" < "-_-"
C# string.CompareOrdinal(), i.e. CompareOrdinal(w1, w2)
";P" > "-_-"
As shown, the result varied! Actually my intuitive result should equal to Method 2 and 4, since the ASCII(';') = 59 which is larger than ASCII('-') = 45 .
So I have no idea why Excel and C# string.CompareTo() gives a opposite answer. Noted that in C# the second comparison function named string.CompareOrdinal(). Does this imply that the default C# string.CompareTo() function is not "Ordinal" ?
Could anyone explain this inconsistency?
And could anyone explain in CultureInfo = {en-US}, why it tells ;P > -_- ? what's the underlying motivation or principle? And I have ever heard about different double multiplication in different cultureInfo. It's rather a cultural shock..!

?
std::string::compare: "the result of a character comparison depends only on its character code". It's simply ordinal.
String.CompareTo: "performs a word (case-sensitive and culture-sensitive) comparison using the current culture". So,this not ordinal, since typical users don't expect things to be sorted like that.
String::CompareOrdinal: Per the name, "performs a case-sensitive comparison using ordinal sort rules".
EDIT: CompareOptions has a hint: "For example, the hyphen ("-") might have a very small weight assigned to it so that "coop" and "co-op" appear next to each other in a sorted list."

Excel 2003 (and earlier) does a sort ignoring hyphens and apostrophes, so your sort really compares ; to _, which gives the result that you have. Here's a Microsoft Support link about it. Pretty sparse, but enough to get the point across.

SQL Server CE 3.5 cuts off strings early (C#)

Hey Everyone, I am writing some code that makes use of SQL Server CE 3.5 and I am having a very strange problem. I have a string field in one of the tables that needs to store a full file path.
Over the course of trying to fix this problem I have that field set as nvarchar with a max size of 4000, but it is still cutting longer strings that are much shorter than the limit off
for example:
D:\iTunes\iTunes Media\Music\Abigail Williams\In The Absence Of Light\02 Final Destiny Of The Gods.m
This is clearly smaller than 4000 characters, yet it is missing the p3 at the end of the string.
I am using a table adapter to enter the data into the database with the following query:
INSERT INTO [Track] ([Artist_ID], [Album_ID], [FilePath], [LastUpdate])
VALUES (#Art, #Al, #Fp, #LU)
I know that the strings are fully formed on insert because I am using the following code to check:
if(!temp.Filepath.EndsWith(".mp3"))
MessageBox.Show("File Error");
this.trackTableAdapter1.InsertQuery(ArtID, AlID, temp.Filepath, File.GetLastWriteTime(temp.Filepath));
The message box does not get shown, so the string must end correctly on insert.
the query that extracts the data is:
SELECT
*
FROM Track
WHERE Artist_ID=#Artist_ID AND Album_ID=#Album_ID
The involved code is:
foreach (Database.MusicDBDataSet.TrackRow TR in this.trackTableAdapter1.GetAlbumTracks(AR.Artist_ID, AlR.Album_ID).Rows)
{
//if (!TR.FilePath.EndsWith(".mp3"))
//MessageBox.Show("File Path Error");
this.ArtistList[AR.Name].AlbumList[this.ArtistList[AR.Name].AlbumList.Count - 1].TrackList.Add(new Track(TR.FilePath, AlR.Name, AR.Name));
}
Has anyone ever run into this problem before?

Check the XSD file. Specifically, check the FilePath column of your table and look for the max length.

Maybe take a look at the SQLServerCE Parameter Size limitation.

What is the specific maximum length? Is it around 100 chars? (Guessing based on your provided input example).
The 100 unicode chars also matches with D.K. Mulligan's answer. Looking at SQL ServerCE Paramater Size Property
For variable-length data types, the Size property describes the maximum amount of data to send to the server. For example, the Size property can be used to limit the amount of data sent to the server for a string value to the first 100 bytes.
For Unicode string data, the Size property refers to the number of characters. The count for strings does not include the terminating character.
Try bumping the size to see if this is the magic number that is truncating your strings.

DB2 ZOS String Comparison Problem

I am comparing some CHAR data in a where clause in my sql like this,
where PRI_CODE < PriCode
The problem I am having is when the CHAR values are of different lengths.
So if PRI_CODE = '0800' and PriCode = '20' it is returning true instead of false.
It looks like it is comparing it like this
'08' < '20'
instead of like
'0800' < '20'
Does a CHAR comparison start from the Left until one or the other values end?
If so how do I fix this?
My values can have letters in it so convering to numeric is not an option.

It's not comparing '08' with '20', it is, as you expect, comparing '0800' with '20'.
What you don't seem to expect, however, is that '0800' (the string) is indeed less than '20' (the string).
If converting it to numerics for a numeric comparison is out of the question, you could use the following DB2 function:
right ('0000000000'||val,10)
which will give you val padded on the left with zeroes to a size of 10 (ideal for a CHAR(10), for example). That will at least guarantee that the fields are the same size and the comparison will work for your particular case. But I urge you to rethink how you're doing things: per-row functions rarely scale well, performance-wise.
If you're using z/OS, you should have a few DBAs just lying around on the computer room floor waiting for work - you can probably ask one of them for advice more tailored to your specific application :-)
One thing that comes to mind in the use of an insert/update trigger and secondary column PRI_CODE_PADDED to hold the PRI_CODE column fully padded out (using the same method as above). Then make sure your PriCode variable is similarly formatted before executing the select ... where PR_CODE_PADDED < PriCode.
Incurring that cost at insert/update time will amortise it over all the selects you're likely to do (which, because they're no longer using per-row functions, will be blindingly fast), giving you better overall performance (assuming your database isn't one of those incredibly rare beasts that are written more than read, of course).