string[] sArray = { APPLE|apple, SOURCE|source, BIOS|bios, APPLE|device };
Above is the string array, and I need to split these array and get before values of pipe symbol **|** using LINQ.
Now am using like this to get into array:
List<string> lVirtualDir = new List<string>();
foreach (string _sArray in sArray)
{
lVirtualDir.Add(_sArray.Remove(cus.IndexOf('|'), _sArray.Length - _sArray.IndexOf('|')));
}
This above code will get result as
APPLE
SOURCE
BIOS
APPLE
I need to sort this code part in LINQ.
This should do it:
lVirtualDir = sArray.Select(x => x.Split('|')[0].Trim())
.OrderBy(x => x).ToList();
Related
I have the following data structure:
Dictionary<string, Dictionary<string, List<int>>> data =
new Dictionary<string, Dictionary<string, List<int>>>();
I want to filter some of the elements in that dictionary based on value in first element of the list of the inner dictionary.
for example:
{legion1
{soldier1, [10,1000]},
{soldier2, [50,1000]}
}
Now let's say I want to do foreach loop in which to work only elements where
the value of the first element of the list is less than 20
expected result in the foreach loop is:
{legion1{soldier1, [10,1000]}}
What I've tried:
I do foreach loop and then I want to use something similar:
data.where(x => x.value.where(o => o[0] < 20 ))
I always get error that that way is incorrect.
Please tell how can I solve the issue and why my way is failing.
You can filter and iterate over the result set like so:
var resultSet =
data.ToDictionary(e => e.Key,
e => e.Value.Where(x => x.Value[0] < 20)
.ToDictionary(k => k.Key, v => v.Value)
);
foreach(var item in resultSet){
var key = item.Key; // string
var values = item.Value; // Dictionary<string, List<int>>
...
...
}
The problem is that you are applying operator [] incorrectly. Moreover, since you want to use both Legion and Soldier, you should construct a tuple combining the two of them:
foreach (var t in data.SelectMany(lg => lg.Value.Select(s => new {
Legion = lg
, Soldier = s
})).Where(ls => ls.Soldier.Value[0] < 20)) {
Console.WriteLine("Legion={0} Soldier = {1}", t.Legion.Key, t.Soldier.Key);
}
I want to sort a list of strings (with possibly duplicate entries) by using as ordering reference the order of the entries in another list. So, the following list is the list I want to sort
List<String> list = ['apple','pear','apple','x','x','orange','x','pear'];
And the list that specifies the order is
List<String> order = ['orange','apple','x','pear'];
And the output should be
List<String> result = ['orange','apple','apple','x','x','x','pear','pear'];
Is there a clean way of doing this?
I don't understand if I can use list's sort and compare with the following problem. I tried using map, iterable, intersection, etc.
There might be a more efficient way but at least you get the desired result:
main() {
List<String> list = ['apple','pear','apple','x','x','orange','x','pear'];
List<String> order = ['orange','apple','x','pear'];
list.sort((a, b) => order.indexOf(a).compareTo(order.indexOf(b)));
print(list);
}
Try it on DartPad
The closure passed to list.sort(...) is a custom comparer which instead of comparing the passed item, compares their position in order and returns the result.
Using a map for better lookup performance:
main() {
List<String> list = ['apple','pear','apple','x','x','orange','x','pear'];
List<String> orderList = ['orange','apple','x','pear'];
Map<String,int> order = new Map.fromIterable(
orderList, key: (key) => key, value: (key) => orderList.indexOf(key));
list.sort((a, b) => order[a].compareTo(order[b]));
print(list);
}
Try it on DartPad
I'm having a list of string like
var target = new List<string>() { "C", "C-sharp", "java" };
I'm having a string request = "C is a programming language"
This list should match with the string and should return
C,C-sharp
How can i do this?
here is the solution with linq
var m = from t in target
where t[0] == 'C'
select t;
Using Linq and String.Contains:
var filtered = target.Where(str => str.Contains("C"));
Another option, without Linq, is to change the existing list using List<T>.RemoveAll:
target.RemoveAll(str => !str.Contains("C"));
If you really need a regex (for something more complex), you may also use:
Regex validate = new Regex(".a.", RegexOptions.IgnoreCase);
var filtered = target.Where(str => validate.Match(str).Success);
I have an array of strings from a log file with the following format:
var lines = new []
{
"--------",
"TimeStamp: 12:45",
"Message: Message #1",
"--------",
"--------",
"TimeStamp: 12:54",
"Message: Message #2",
"--------",
"--------",
"Message: Message #3",
"TimeStamp: 12:55",
"--------"
}
I want to group each set of lines (as delimited by "--------") into a list using LINQ. Basically, I want a List<List<string>> or similar where each inner list contains 4 strings - 2 separators, a timestamp and a message.
I should add that I would like to make this as generic as possible, as the log-file format could change.
Can this be done?
Will this work?
var result = Enumerable.Range(0, lines.Length / 4)
.Select(l => lines.Skip(l * 4).Take(4).ToList())
.ToList()
EDIT:
This looks a little hacky but I'm sure it can be cleaned up
IEnumerable<List<String>> GetLogGroups(string[] lines)
{
var list = new List<String>();
foreach (var line in lines)
{
list.Add(line);
if (list.Count(l => l.All(c => c == '-')) == 2)
{
yield return list;
list = new List<string>();
}
}
}
You should be able to actually do better than returning a List>. If you're using C# 4, you could project each set of values into a dynamic type where the string before the colon becomes the property name and the value is on the left-hand side. You then create a custom iterator which reads the lines until the end "------" appears in each set and then yield return that row. On MoveNext, you read the next set of lines. Rinse and repeat until EOF. I don't have time at the moment to write up a full implementation, but my sample on reading in CSV and using LINQ over the dynamic objects may give you an idea of what you can do. See http://www.thinqlinq.com/Post.aspx/Title/LINQ-to-CSV-using-DynamicObject. (note this sample is in VB, but the same can be done in C# as well with some modifications).
The iterator implementation has the added benefit of not having to load the entire document into memory before parsing. With this version, you only load the amount for one set of blocks at a time. It allows you to handle really large files.
Assuming that your structure is always
delimeter
TimeStamp
Message
delimeter
public List<List<String>> ConvertLog(String[] log)
{
var LogSet = new List<List<String>>();
for(i = 0; i < log.Length(); i += 4)
{
if (log.Length <= i+3)
{
var set = new List<String>() { log[i], log[i+1], log[i+2], log[i+3] };
LogSet.Add(set);
}
}
}
Or in Linq
public List<List<String> ConvertLog(String[] log)
{
return Enumerable.Range(0, lines.Length / 4)
.Select(l => lines.Skip(l * 4).Take(4).ToList())
.ToList()
}
Suppose I have the following list:
var strings = new List<string>();
strings.Add("1");
strings.Add("12.456");
strings.Add("Foobar");
strings.Add("0.56");
strings.Add("zero");
Is there some sort of query I can write in Linq that will return to me only the numeric items, i.e. the 1st, 2nd, and 4th items from the list?
-R.
strings.Where(s => { double ignored; return double.TryParse(s, out ignored); })
This will return all the strings that are parseable as doubles as strings. If you want them as numbers (which makes more sense), you could write an extension method:
public static IEnumerable<double> GetDoubles(this IEnumerable<string> strings)
{
foreach (var s in strings)
{
double result;
if (double.TryParse(s, out result))
yield return result;
}
}
Don't forget that double.TryParse() uses your current culture, so it will give different results on different computers. If you don't want that, use double.TryParse(s, NumberStyles.AllowDecimalPoint, CultureInfo.InvariantCulture, out result).
Try this:
double dummy = 0;
var strings = new List<string>();
strings.Add("1");
strings.Add("12.456");
strings.Add("Foobar");
strings.Add("0.56");
strings.Add("zero");
var numbers = strings.Where(a=>double.TryParse(a, out dummy));
You could use a simple predicate to examine each string, like so:
var strings = new List<string>();
strings.Add("1");
strings.Add("12.456");
strings.Add("Foobar");
strings.Add("0.56");
strings.Add("zero");
var nums = strings.Where( s => s.ToCharArray().All( n => Char.IsNumber( n ) || n == '.' ) );