Hi i want to make this code but with BigInteger how i could do it?
Original code
int v=100;
ArrayList<Integer>[] lists;
lists = new ArrayList[v];
I want this exact code but instead of int, BigInteger is that possible?, I tried to to this
BigInteger v=BigInteger.valueOf(100);
ArrayList<BigInteger>[] lists;
lists = new ArrayList[v];
obviously does not work , i want to know which data structure i can use.
Related
I have a program that will create orders for a bunch of orders. However API has limitation that if I wanna do that I got to do it 10 at a time
If orderList.Count > 10 Then
Dim FirstTwenty = From n In orderList Take (10)
Dim theRest = From n In orderList Skip (10)
Dim result1 = Await internalActualcreateNormalLimitOrderMultiple(FirstTwenty.ToArray)
Dim result2 = Await internalActualcreateNormalLimitOrderMultiple(theRest.ToArray)
Return result1 + result2 'no longer json but we don't really use the resulting json unless for debugging
End If
Basically I want to split {1,2,3,4,5,6,7,8,9,10.11.12,...} into {1,2,3}{4,5,6},{7,8,9},...
And I wonder if I can use linq instead of for each
So I use this recursive function. Get first 10 or twenty and then recursively call the function and so on.
And I look at it and while it's simple, it doesn't seem right. Obviously number of orders won't be big. At most 15. But what about if on day I have 100? I can get like stackoverflow for recursive things.
If only there is a function that can split arrays into array using linq, where, take, and skip that'll be great.
Of course I can do for each but perhaps there is a more elegant way?
Then I wrote another code
Public Shared Function splitArrayIntoSmallerArrays(Of someObject)(arrayOfSomeObject As someObject(), chunkSize As Integer) As List(Of someObject())
Dim output = New List(Of someObject())
Dim newestArray = New List(Of someObject)
For i = 0 To arrayOfSomeObject.Count - 1
newestArray.Add(arrayOfSomeObject(i))
If newestArray.Count = chunkSize Then
output.Add(newestArray.ToArray)
newestArray = New List(Of someObject)
End If
Next
output.Add(newestArray.ToArray)
Return output
End Function
That'll do it in O(n)
But I think it can be done more simply by using linq, seek, and take but I don't know how. Or may be group by.
Any idea?
Your question was not very clear to me, but I believe you have an array with several "objects" inside it, correct? And before that you want to divide this matrix into smaller matrices, correct?
So how about passing this larger matrix to a JSON, creating an object that will be filled in by the smaller values and then transforming this JSON again into objects of the type above, then passing these objects to the smaller array, do you understand?
If you have access to Net 7.0, perhaps you're looking for Enumerable.Chunk?
Splits the elements of a sequence into chunks of size at most size.
Sorry if the problem is so basic, I'm a bit used to python not VB.net
I'm trying to read text file data (numbers) and store it in array/list
# Sample of text
1.30e+03,1.30e+03,1.30e+03
5.4600e+02,2.7700e+02,2.8000e+02
# PS: I can control the output of the numbers to have delimiter = ',' or space between numbers, whatever is easier to import
I wrote the following code to read string data and store it. yet, I don't know how to have a multidimensional array (2D or 3D) instead of 1D string (e.g. for the text above, it would be 2x3 array)
' Import Data
Comp_path = FinalPath & "Components_colors.txt"
reader = New StreamReader(Comp_path)
Dim W As String = ""
Dim wArray(10) As String
Dim i As Integer = 0
Do Until reader.Peek = -1
W = reader.ReadLine()
wArray(i) = W
i += 1
Loop
Moreover, I don't know the length of the text file, so I can't determine the length of the array like I did in the code above for the string wArray
For a file like this, you should turn to NuGet for a dedicated CSV parser. There are parsers built into .NET you could also use, but pulling one off of NuGet will also let you parse the values directly into something other than a string.
But if you really don't want to do that you can start with this (assuming Option Infer):
Public Function ImportData(filePath As String) As IEnumerable(Of Double())
Dim lines = File.ReadLines(filePath)
Return lines.Select(Function(line) line.Split(",").Select(AddressOf Double.Parse).ToArray())
End Function
And use it like this:
Comp_path = FinalPath & "Components_colors.txt"
Dim result = ImportData(Comp_path)
Note this code doesn't actually do any meaningful work yet. It doesn't even read the file. What it does is give you an object (result) that you can use with a For Each loop or linq operations. It will read the file in a just-in-time way, parsing out the data for each line as it goes. If you want an array (or List, which you should use in .Net more often), you can append a ToList() call to the end:
Comp_path = FinalPath & "Components_colors.txt"
Dim result = ImportData(Comp_path).ToList()
But you should try to avoid doing that it. It's much less efficient in terms of memory use. The first sample will only ever need to keep one line of the file in memory at a time. Adding ToArray() or ToList() needs to load the entire file.
Some more notes:
Many newer dynamic platforms like Python don't actually use real arrays in the formal computer science sense (fixed block of contiguous memory). Rather, they use collections, and just call them arrays. .Net has collections, too, but when you declare an array, you get an array. This has nice benefits for performance, but if you don't know you want that or how to take advantage of it you're probably better off asking for a generic List most of the time instead.
Thanks to cultural/internationalization issues, parsing numeric (or date) values to string and back again is much slower and more error-prone than you've believed in the past, especially coming from a dynamic platform. It is slow on these other platforms, too, but they want you to pretend it isn't. The first introduction to a strongly-typed platform like .Net can feel stifling in this area, but once you understand the performance and and reliability benefits, you won't want to go back.
In strongly-typed platforms it is very important to understand the data types you are working with at every level of an expression. Otherwise, building and reading statements like the Return line in my answer will be way more difficult and frustrating than it needs to be.
Thanks to #RedBassett for this Ressource (Kotlin problem solving): https://kotlinlang.org/docs/tutorials/koans.html
I'm aware this question exists here:
Creating a 4 digit Random Number using java with no repetition in digits
but I'm new to Kotlin and would like to explore the direct Kotlin features.
So as the title suggests, I'm trying to find a Kotlin specific way to nicely solve generate a 4 digit number (after that it's easy to make it adaptable for length x) without repeating digits.
This is my current working solution and would like to make it more Kotlin. Would be very grateful for some input.
fun createFourDigitNumber(): Int {
var fourDigitNumber = ""
val rangeList = {(0..9).random()}
while(fourDigitNumber.length < 4)
{
val num = rangeList().toString()
if (!fourDigitNumber.contains(num)) fourDigitNumber +=num
}
return fourDigitNumber.toInt()
}
So the range you define (0..9) is actually already a sequence of numbers. Instead of iterating and repeatedly generating a new random, you can just use a subset of that sequence. In fact, this is the accepted answer's solution to the question you linked. Here are some pointers if you want to implement it yourself to get the practice:
The first for loop in that solution is unnecessary in Kotlin because of the range. 0..9 does the same thing, you're on the right track there.
In Kotlin you can call .shuffled() directly on the range without needing to call Collections.shuffle() with an argument like they do.
You can avoid another loop if you create a string from the whole range and then return a substring.
If you want to look at my solution (with input from others in the comments), it is in a spoiler here:
fun getUniqueNumber(length: Int) = (0..9).shuffled().take(length).joinToString('')
(Note that this doesn't gracefully handle a length above 10, but that's up to you to figure out how to implement. It is up to you to use subList() and then toString(), or toString() and then substring(), the output should be the same.)
I am trying to get a column in a dataframe form float to string. I have tried
df = readtable("data.csv", coltypes = {String, String, String, String, String, Float64, Float64, String});
but I got complained
syntax: { } vector syntax is discontinued
I also have tried
dfB[:serial] = string(dfB[:serial])
but it didn't work either. So, I'd like to know what would be the proper approach to change column data type in Julia.
thx
On your first attempt, Julia tells you what the problem is - you can't make a vector with {}, you need to use []. Also, the name of the keyword argument should be eltypes rather than coltypes.
On the second try, you don't have a float, you have a Vector of floats. So to change the type you need to change the type of all elements. In Julia, elementwise operations on vectors are generalized by the 'dot' syntax, e.g. string.(collect(dfB[:serial])) . The collect is needed currently to cast the DataArray to a normal Array first – this will fail if the DataArray contains NAs. IMHO the DataFrames interface is still rather wonky, so expect a few headaches like this ATM.
having a bit of trouble finding a solution to this.
I want to take a large ordered text file of words and create - in the same order - a text file of fixed length numeric values.
For example:
Input File Output File
AAA -> 00000001
AAH -> 00002718
AAZ -> 71827651
Initially it seemed a hash function would do the trick. However they are one way. Also perhaps they are a bit "heavyweight" for this. After all, I don't need any cryptography. Plus, it's a reference file. It will never change.
Any compression is a bonus not essential. That said, I don't want the file to get any bigger than it already is. Which is why I don't just want to write out the words as text but with fixed lengths.
So, bottom line; input is a NSString of variable length, output is an integer of fixed length. And, I must be able to take the integer and figure out the string.
Any help much appreciated!
Thanks!
xj
Well, this would be a bit of a brute force method, but here's my guess.
Start by making a custom function to convert one letter of text to an integer less than 100. (I'm not sure if such a function already exists, if so then great!) You might need to just go to stuff like "if ([input isEqual: #"a"]){ return 1;}
Then, run that function on each letter of text, and get the final integer by combining the previous results.
For example:
int myVal1 = [intConverter firstLetter];
int myVal2 = [intConverter secondLetter];
int myVal3 = [intConverter thirdLetter];
int finalValue =100^3 + 100^2*myVal1 + 100*myVal2 + myVal3;
Then, finalValue would be of the form 1(myVal1)(myVal2)(myVal3), which is what I think you're looking for.
To get back the original string, simply use the mod (%) and division functions to get the individual values back, then run the intConverter function backwards. (This would probably mean writing a new function that basically runs those if statements in reverse, but oh well.)
I hope this helps.