g-coin | simple implementation of Blockchain | Cryptocurrency library
kandi X-RAY | g-coin Summary
kandi X-RAY | g-coin Summary
A simple implementation of Blockchain for understanding easily. It includes only basic concepts. ※ 아래 글은 최신 버전의 코드가 반영되어 있지 않습니다. 참고해주세요.
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Top functions reviewed by kandi - BETA
- Load blocks from a chain
- Return an account object
- Add a block to the chain
- Apply a list of transactions
- Add a new transaction to the blockchain
- Checks the balance of a given transaction
- Add a transaction to the chain
- Return the sum of the amounts
- Replace the consensus
- Check if proof is valid
- Fetch the chain associated with the given address
- Fetch the block chain with the given neighbors
- Return the hash of the block
- Return a dictionary representation of the transaction
- Compute the hash of the header
- Dump the difficulty proof
- Find the proof of a block
- Validate the proof
- Validate the blockchain
g-coin Key Features
g-coin Examples and Code Snippets
Community Discussions
Trending Discussions on g-coin
QUESTION
I am scraping a HTML and storing data in a pandas dataframe. I need a loop for because the data in the html is in more than one url. My first idea was to create as many data frames as url I have, creating many variables but I have read that this is a bad idea. The solution I have read is to create a dict but I dont see how I can do this with data frames. I just want a final data frame with the information from the first row of the first data frame to the last row of the last dataframe.
This is my code so far
...ANSWER
Answered 2021-Mar-13 at 16:15You can do this way with pd.concat,
QUESTION
coins = ['big-coin-','coins','bitcoin']
for coin in coins:
if coin.endswith('-'):
coin = coin.replace('-','')
print(coin)
print(coins)
ANSWER
Answered 2020-Jul-30 at 19:56this uses a list comprehension to create a new list by removing all trailing - from every string present in the old list.
QUESTION
I'm trying to display the relative file path to my program file in a cout statement so it appears on the screen. This is what I have written down, but the computer mistakes the backslash as an exit sequence. It presents the following error:
Fross12.cpp:62:12: warning: unknown escape sequence: '\C'
This is the code I have written that I'm working with:
...ANSWER
Answered 2020-Apr-10 at 19:35Either use \\ to escape the backslash character so it's not interpreted special, or just use forward slashes / - That works on both Windows, Unix and other Operating Systems.
You can also use a raw string literal like R"my_raw_str(C:\whatever)my_raw_str".
You could also use a std::filesystem::path which takes care of all the details for you.
QUESTION
Given a list of n-element lists, A, and a target n-element list, t, find a set of lists, S, in A, whose lists sum up to t.
Summing up lists, here, is the addition of elements at the same position. For example, the sum of [1 2] + [2 3] + [7 5] is [10 10].
Here is an example of the problem:
n = 4
A = [[1 2 3 4] [0 0 1 0] [1 0 0 1] [2 0 0 0] [3 0 0 2] [3 0 0 1] [0 0 0 1]]
t = [4 0 1 3]
Then, we must find S.
S = [[3 0 0 1] [0 0 0 1] [0 0 1 0] [1 0 0 1]]
Notice that we don't need all the sets of lists that add up to t -- we only need one.
This problem may seem similar to the dynamic programming coin change that return an array.
Obviously, this problem can be done in brute force with time complexity of O(2^n) by going over the power set of A. Is there a more optimal solution? Is there another problem similar to this?
...ANSWER
Answered 2020-Jan-28 at 03:36Solving your problem is equivalent to solving Subset sum problem, which is NP-complete, so your problem is NP-complete too. It means that your problem can't be solved in polynomial time.
Although, if absolute values of all numbers in your lists are less than M, there is a subset sum problem solution in O(n*M*size(a)) (you just need to modify it to your problem, but it is still exponential relatively to number of bits in numbers and takes a lot of memory, but may be better than brute force in certain cases).
QUESTION
So I'm not quite sure what I'm doing wrong, but I'm bumping into a cross-origin request blocked issue when trying to make an API call to chasing-coins. Two reasons shown:
- CORS header 'Access-Control-Allow-Origin' missing
- CORS request did not succeed
This is my code
...ANSWER
Answered 2018-Oct-08 at 01:18This is related to a CORS issue with the server hosting the API. The source API has not set a configuration to allow browsers to request the resource from different origins, so any requests made from different origins with a browser will end up a pre-flight error.
The pre-flight error occurs during the TCP/IP handshake request and it's at this moment that the origin is confirmed and if the server is not configured to handle cross origin requests, the browser will not fulfil the request as expected.
To get around this, you will need to use a backend server such as nodejs to query the API and server it to your front-end code. This will work because nodejs does not have a CORS policy when requesting resource from external APIs.
This is also why CURL and apps like Postman will work with the API, because the also don't enforce the CORS policy on the request.
QUESTION
I am completely stuck, and I have been searching for days, It probably doesn't help that I am a complete and total noob. All of the apis that I call in web reference give me this in the little preview box:
...ANSWER
Answered 2018-Jun-01 at 23:40This should be pretty easy!
All you have to do is call the api from your view controller asynchronously and wait for the api server to send a response back. This will most likely come back in the form of a JSON object and C# has lots of great libraries for storing and manipulating JSON data (most notably Newtonsoft.JSON)
Once you get the data back, store it as a JSON object and then pass whatever information to the label that you would like to display.
It might look something like this:(be sure to include Newtonsoft.Json.Linq)
QUESTION
I am building a system which detects coins that are picked up from a tray. This tray will be kept in a public place. People will pick up one or more coins, but would be expected to keep them back after some time.
I would have a live stream through a webcam placed at the top. I will have a calibration step, say at the beginning of the day, that captures the initial state of the tray to be used for comparing with the live feed. A few slots might be empty to begin with, as you can see in the sample image.
I need to detect slots that had a coin initially, but are missing the same at any given point of time during the day.
I am trying out a few approaches using OpenCV:
SSIM difference: I can use SSIM to find diff between my live image frame and initial state. However, a number of slots are larger than the corresponding coin sizes (e.g. top two rows). This could mean that if the coin was originally placed at the center, but was later put back to touch one of the edges, we may get a false positive.
Blob detection: Alternatively, I can pre-feed (or detect) slot co-ordinates. Then do a blob detection within every slot. If a blob was present in the original state, but is missing in a camera frame, this would mean a coin has been picked up. However, accurate blob detection could be a challenge if the contrast between the coin and the tray is low.
I might also need to watch out for slight variations in lighting due to shadows of people moving around.
Any thoughts on these or any pointers on alternate approaches that can be tried out? Is there any analogous implementation that I can learn from?
Many thanks in advance.
Edit: Thanks to @I.Newton's suggestion. For those who stumble upon this question and would benefit from a sample implementation, look here: https://github.com/kewats/computer-vision-samples/tree/master/image-processing/missing-coins-detection
...ANSWER
Answered 2018-Feb-09 at 07:06If you complete control over the lighting conditions, you can use simple color thresholding to solve the problem.
First make a mask for the boxes. You can do it in multiple ways by color threshold or by using adaptive threshold or canny edge etc. I did by color threshold
Then make a mask for the coins by the same method.
Now flood fill your box mask from from the center of each of this coins. It'll retain only those which do not have the coins.
Now you can compare this with your initial mask to figure out if all the coins are present
This does not include frame subtraction. So you need not worry about different position of coin in the box. Only thing you need to make sure is the lighting conditions for making the masks. If you want to make sure the coins are returned to the same box, you should go for template matching etc which again needs effort.
QUESTION
So I want to convert a JsonElement into multiple or one big Array. Im not really sure whats the right idea. Sadly, I dont even know how to start. Maybe some one could help me out. Why do I even need the Pojo Class if need to convert the JsonElement myself. I would be glad if someone could point out my problems.
Api Response:
...ANSWER
Answered 2018-Jan-27 at 03:56You can use Android Networking Library
https://github.com/amitshekhariitbhu/Fast-Android-Networking
on response you can create JsonObject
JSONObject currency = new JSONObject(response.toString());
JSONArray lisOfcur = currency.getJSONArray("list_of_cur");
QUESTION
If I try to get data from my Retrofit call, its empty. Probably because I use the wrong datatype.Not sure if its an Array or an ArrayList Maybe some one could help me out.
Api : https://chasing-coins.com/api/v1/top-coins/100
Interface :
...ANSWER
Answered 2018-Jan-27 at 01:39The result is not an array. It is an object.
You can try this:
QUESTION
I am using Retrofit2 for the first time and have a problem to get a simple Array in non JSON format.
Error: java.lang.IllegalStateException: Expected BEGIN_OBJECT but was STRING at line 1 column 3 path $[0]
This means its not an JSON Object since it does not start with "{"
I tried adding the ScalarsConverter but it doesent seems to work.
Api: https://chasing-coins.com/api/v1/coins
Interface:
...ANSWER
Answered 2018-Jan-23 at 18:16When you are using private List coinlist;, Gson expects the object to be
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Install g-coin
You can use g-coin like any standard Python library. You will need to make sure that you have a development environment consisting of a Python distribution including header files, a compiler, pip, and git installed. Make sure that your pip, setuptools, and wheel are up to date. When using pip it is generally recommended to install packages in a virtual environment to avoid changes to the system.
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