Scrap-books-using-Beautifulsoup-from-books.toscrape

This jupyter notebook is used to demonstrate our recent work, "DeepLOB: Deep Convolutional Neural Networks for Limit Order Books", published in IEEE Transactions on Singal Processing. We use FI-2010 dataset and present how model architecture is constructed here. The FI-2010 is publicly avilable and interested readers can check out their paper.

A simple library and Jupyter notebook example that can propagate a gaussian laser beam through free space and through optical elements using ABCD matrices and the q-parameter. Personally, it is quicker than setting up a zemax file, and allows me to check beam sizes, waist locations, and calculate distances need for collimation optics.

BUILD YOUR OWN BLOCKCHAIN: A PYTHON TUTORIAL Download the full Jupyter/iPython notebook from Github here Build Your Own Blockchain – The Basics¶ This tutorial will walk you through the basics of how to build a blockchain from scratch. Focusing on the details of a concrete example will provide a deeper understanding of the strengths and limitations of blockchains. For a higher-level overview, I’d recommend this excellent article from BitsOnBlocks. Transactions, Validation, and updating system state¶ At its core, a blockchain is a distributed database with a set of rules for verifying new additions to the database. We’ll start off by tracking the accounts of two imaginary people: Alice and Bob, who will trade virtual money with each other. We’ll need to create a transaction pool of incoming transactions, validate those transactions, and make them into a block. We’ll be using a hash function to create a ‘fingerprint’ for each of our transactions- this hash function links each of our blocks to each other. To make this easier to use, we’ll define a helper function to wrap the python hash function that we’re using. In [1]: import hashlib, json, sys def hashMe(msg=""): # For convenience, this is a helper function that wraps our hashing algorithm if type(msg)!=str: msg = json.dumps(msg,sort_keys=True) # If we don't sort keys, we can't guarantee repeatability! if sys.version_info.major == 2: return unicode(hashlib.sha256(msg).hexdigest(),'utf-8') else: return hashlib.sha256(str(msg).encode('utf-8')).hexdigest() Next, we want to create a function to generate exchanges between Alice and Bob. We’ll indicate withdrawals with negative numbers, and deposits with positive numbers. We’ll construct our transactions to always be between the two users of our system, and make sure that the deposit is the same magnitude as the withdrawal- i.e. that we’re neither creating nor destroying money. In [2]: import random random.seed(0) def makeTransaction(maxValue=3): # This will create valid transactions in the range of (1,maxValue) sign = int(random.getrandbits(1))*2 - 1 # This will randomly choose -1 or 1 amount = random.randint(1,maxValue) alicePays = sign * amount bobPays = -1 * alicePays # By construction, this will always return transactions that respect the conservation of tokens. # However, note that we have not done anything to check whether these overdraft an account return {u'Alice':alicePays,u'Bob':bobPays} Now let’s create a large set of transactions, then chunk them into blocks. In [3]: txnBuffer = [makeTransaction() for i in range(30)] Next step: making our very own blocks! We’ll take the first k transactions from the transaction buffer, and turn them into a block. Before we do that, we need to define a method for checking the valididty of the transactions we’ve pulled into the block. For bitcoin, the validation function checks that the input values are valid unspent transaction outputs (UTXOs), that the outputs of the transaction are no greater than the input, and that the keys used for the signatures are valid. In Ethereum, the validation function checks that the smart contracts were faithfully executed and respect gas limits. No worries, though- we don’t have to build a system that complicated. We’ll define our own, very simple set of rules which make sense for a basic token system: The sum of deposits and withdrawals must be 0 (tokens are neither created nor destroyed) A user’s account must have sufficient funds to cover any withdrawals If either of these conditions are violated, we’ll reject the transaction. In [4]: def updateState(txn, state): # Inputs: txn, state: dictionaries keyed with account names, holding numeric values for transfer amount (txn) or account balance (state) # Returns: Updated state, with additional users added to state if necessary # NOTE: This does not not validate the transaction- just updates the state! # If the transaction is valid, then update the state state = state.copy() # As dictionaries are mutable, let's avoid any confusion by creating a working copy of the data. for key in txn: if key in state.keys(): state[key] += txn[key] else: state[key] = txn[key] return state In [5]: def isValidTxn(txn,state): # Assume that the transaction is a dictionary keyed by account names # Check that the sum of the deposits and withdrawals is 0 if sum(txn.values()) is not 0: return False # Check that the transaction does not cause an overdraft for key in txn.keys(): if key in state.keys(): acctBalance = state[key] else: acctBalance = 0 if (acctBalance + txn[key]) < 0: return False return True Here are a set of sample transactions, some of which are fraudulent- but we can now check their validity! In [6]: state = {u'Alice':5,u'Bob':5} print(isValidTxn({u'Alice': -3, u'Bob': 3},state)) # Basic transaction- this works great! print(isValidTxn({u'Alice': -4, u'Bob': 3},state)) # But we can't create or destroy tokens! print(isValidTxn({u'Alice': -6, u'Bob': 6},state)) # We also can't overdraft our account. print(isValidTxn({u'Alice': -4, u'Bob': 2,'Lisa':2},state)) # Creating new users is valid print(isValidTxn({u'Alice': -4, u'Bob': 3,'Lisa':2},state)) # But the same rules still apply! True False False True False Each block contains a batch of transactions, a reference to the hash of the previous block (if block number is greater than 1), and a hash of its contents and the header Building the Blockchain: From Transactions to Blocks¶ We’re ready to start making our blockchain! Right now, there’s nothing on the blockchain, but we can get things started by defining the ‘genesis block’ (the first block in the system). Because the genesis block isn’t linked to any prior block, it gets treated a bit differently, and we can arbitrarily set the system state. In our case, we’ll create accounts for our two users (Alice and Bob) and give them 50 coins each. In [7]: state = {u'Alice':50, u'Bob':50} # Define the initial state genesisBlockTxns = [state] genesisBlockContents = {u'blockNumber':0,u'parentHash':None,u'txnCount':1,u'txns':genesisBlockTxns} genesisHash = hashMe( genesisBlockContents ) genesisBlock = {u'hash':genesisHash,u'contents':genesisBlockContents} genesisBlockStr = json.dumps(genesisBlock, sort_keys=True) Great! This becomes the first element from which everything else will be linked. In [8]: chain = [genesisBlock] For each block, we want to collect a set of transactions, create a header, hash it, and add it to the chain In [9]: def makeBlock(txns,chain): parentBlock = chain[-1] parentHash = parentBlock[u'hash'] blockNumber = parentBlock[u'contents'][u'blockNumber'] + 1 txnCount = len(txns) blockContents = {u'blockNumber':blockNumber,u'parentHash':parentHash, u'txnCount':len(txns),'txns':txns} blockHash = hashMe( blockContents ) block = {u'hash':blockHash,u'contents':blockContents} return block Let’s use this to process our transaction buffer into a set of blocks: In [10]: blockSizeLimit = 5 # Arbitrary number of transactions per block- # this is chosen by the block miner, and can vary between blocks! while len(txnBuffer) > 0: bufferStartSize = len(txnBuffer) ## Gather a set of valid transactions for inclusion txnList = [] while (len(txnBuffer) > 0) & (len(txnList) < blockSizeLimit): newTxn = txnBuffer.pop() validTxn = isValidTxn(newTxn,state) # This will return False if txn is invalid if validTxn: # If we got a valid state, not 'False' txnList.append(newTxn) state = updateState(newTxn,state) else: print("ignored transaction") sys.stdout.flush() continue # This was an invalid transaction; ignore it and move on ## Make a block myBlock = makeBlock(txnList,chain) chain.append(myBlock) In [11]: chain[0] Out[11]: {'contents': {'blockNumber': 0, 'parentHash': None, 'txnCount': 1, 'txns': [{'Alice': 50, 'Bob': 50}]}, 'hash': '7c88a4312054f89a2b73b04989cd9b9e1ae437e1048f89fbb4e18a08479de507'} In [12]: chain[1] Out[12]: {'contents': {'blockNumber': 1, 'parentHash': '7c88a4312054f89a2b73b04989cd9b9e1ae437e1048f89fbb4e18a08479de507', 'txnCount': 5, 'txns': [{'Alice': 3, 'Bob': -3}, {'Alice': -1, 'Bob': 1}, {'Alice': 3, 'Bob': -3}, {'Alice': -2, 'Bob': 2}, {'Alice': 3, 'Bob': -3}]}, 'hash': '7a91fc8206c5351293fd11200b33b7192e87fad6545504068a51aba868bc6f72'} As expected, the genesis block includes an invalid transaction which initiates account balances (creating tokens out of thin air). The hash of the parent block is referenced in the child block, which contains a set of new transactions which affect system state. We can now see the state of the system, updated to include the transactions: In [13]: state Out[13]: {'Alice': 72, 'Bob': 28} Checking Chain Validity¶ Now that we know how to create new blocks and link them together into a chain, let’s define functions to check that new blocks are valid- and that the whole chain is valid. On a blockchain network, this becomes important in two ways: When we initially set up our node, we will download the full blockchain history. After downloading the chain, we would need to run through the blockchain to compute the state of the system. To protect against somebody inserting invalid transactions in the initial chain, we need to check the validity of the entire chain in this initial download. Once our node is synced with the network (has an up-to-date copy of the blockchain and a representation of system state) it will need to check the validity of new blocks that are broadcast to the network. We will need three functions to facilitate in this: checkBlockHash: A simple helper function that makes sure that the block contents match the hash checkBlockValidity: Checks the validity of a block, given its parent and the current system state. We want this to return the updated state if the block is valid, and raise an error otherwise. checkChain: Check the validity of the entire chain, and compute the system state beginning at the genesis block. This will return the system state if the chain is valid, and raise an error otherwise. In [14]: def checkBlockHash(block): # Raise an exception if the hash does not match the block contents expectedHash = hashMe( block['contents'] ) if block['hash']!=expectedHash: raise Exception('Hash does not match contents of block %s'% block['contents']['blockNumber']) return In [15]: def checkBlockValidity(block,parent,state): # We want to check the following conditions: # - Each of the transactions are valid updates to the system state # - Block hash is valid for the block contents # - Block number increments the parent block number by 1 # - Accurately references the parent block's hash parentNumber = parent['contents']['blockNumber'] parentHash = parent['hash'] blockNumber = block['contents']['blockNumber'] # Check transaction validity; throw an error if an invalid transaction was found. for txn in block['contents']['txns']: if isValidTxn(txn,state): state = updateState(txn,state) else: raise Exception('Invalid transaction in block %s: %s'%(blockNumber,txn)) checkBlockHash(block) # Check hash integrity; raises error if inaccurate if blockNumber!=(parentNumber+1): raise Exception('Hash does not match contents of block %s'%blockNumber) if block['contents']['parentHash'] != parentHash: raise Exception('Parent hash not accurate at block %s'%blockNumber) return state In [16]: def checkChain(chain): # Work through the chain from the genesis block (which gets special treatment), # checking that all transactions are internally valid, # that the transactions do not cause an overdraft, # and that the blocks are linked by their hashes. # This returns the state as a dictionary of accounts and balances, # or returns False if an error was detected ## Data input processing: Make sure that our chain is a list of dicts if type(chain)==str: try: chain = json.loads(chain) assert( type(chain)==list) except: # This is a catch-all, admittedly crude return False elif type(chain)!=list: return False state = {} ## Prime the pump by checking the genesis block # We want to check the following conditions: # - Each of the transactions are valid updates to the system state # - Block hash is valid for the block contents for txn in chain[0]['contents']['txns']: state = updateState(txn,state) checkBlockHash(chain[0]) parent = chain[0] ## Checking subsequent blocks: These additionally need to check # - the reference to the parent block's hash # - the validity of the block number for block in chain[1:]: state = checkBlockValidity(block,parent,state) parent = block return state We can now check the validity of the state: In [17]: checkChain(chain) Out[17]: {'Alice': 72, 'Bob': 28} And even if we are loading the chain from a text file, e.g. from backup or loading it for the first time, we can check the integrity of the chain and create the current state: In [18]: chainAsText = json.dumps(chain,sort_keys=True) checkChain(chainAsText) Out[18]: {'Alice': 72, 'Bob': 28} Putting it together: The final Blockchain Architecture¶ In an actual blockchain network, new nodes would download a copy of the blockchain and verify it (as we just did above), then announce their presence on the peer-to-peer network and start listening for transactions. Bundling transactions into a block, they then pass their proposed block on to other nodes. We’ve seen how to verify a copy of the blockchain, and how to bundle transactions into a block. If we recieve a block from somewhere else, verifying it and adding it to our blockchain is easy. Let’s say that the following code runs on Node A, which mines the block: In [19]: import copy nodeBchain = copy.copy(chain) nodeBtxns = [makeTransaction() for i in range(5)] newBlock = makeBlock(nodeBtxns,nodeBchain) Now assume that the newBlock is transmitted to our node, and we want to check it and update our state if it is a valid block: In [20]: print("Blockchain on Node A is currently %s blocks long"%len(chain)) try: print("New Block Received; checking validity...") state = checkBlockValidity(newBlock,chain[-1],state) # Update the state- this will throw an error if the block is invalid! chain.append(newBlock) except: print("Invalid block; ignoring and waiting for the next block...") print("Blockchain on Node A is now %s blocks long"%len(chain)) Blockchain on Node A is currently 7 blocks long New Block Received; checking validity... Blockchain on Node A is now 8 blocks long

Python script and Jupyter Notebook, to check for, and plot a weathergami (all max/min combinations) for a given station in the ACIS database.

Understanding gender differences in professional European football through Machine Learning interpretability and match actions data. This repository contains the full data pipeline implemented for the study *Understanding gender differences in professional European football through Machine Learning interpretability and match actions data*. We evaluated European male, and female football players' main differential features in-match actions data under the assumption of finding significant differences and established patterns between genders. A methodology for unbiased feature extraction and objective analysis is presented based on data integration and machine learning explainability algorithms. Female (1511) and male (2700) data points were collected from event data categorized by game period and player position. Each data point included the main tactical variables supported by research and industry to evaluate and classify football styles and performance. We set up a supervised classification pipeline to predict the gender of each player by looking at their actions in the game. The comparison methodology did not include any qualitative enrichment or subjective analysis to prevent biased data enhancement or gender-related processing. The pipeline had three representative binary classification models; A logic-based Decision Trees, a probabilistic Logistic Regression and a multilevel perceptron Neural Network. Each model tried to draw the differences between male and female data points, and we extracted the results using machine learning explainability methods to understand the underlying mechanics of the models implemented. A good model predicting accuracy was consistent across the different models deployed. ## Installation Install the required python packages ``` pip install -r requirements.txt ``` To handle heterogeneity and performance efficiently, we use PySpark from [Apache Spark](https://spark.apache.org/). PySpark enables an end-user API for Spark jobs. You might want to check how to set up a local or remote Spark cluster in [their documentation](https://spark.apache.org/docs/latest/api/python/index.html). ## Repository structure This repository is organized as follows: - Preprocessed data from the two different data streams is collecting in [the data folder](data/). For the Opta files, it contains the event-based metrics computed from each match of the 2017 Women's Championship and a single file calculating the event-based metrics from the 2016 Men's Championship published [here](https://figshare.com/collections/Soccer_match_event_dataset/4415000/5). Even though we cannot publish the original data source, the two python scripts implemented to homogenize and integrate both data streams into event-based metrics are included in [the data gathering folder](data_gathering/) folder contains the graphical images and media used for the report. - The [data cleaning folder](data_cleaning/) contains descriptor scripts for both data streams and [the final integration](data_cleaning/merger.py) - [Classification](classification/) contains all the Jupyter notebooks for each model present in the experiment as well as some persistent models for testing.

A collection of helpful functions for use with nbgrader; automatically fix broken notebooks whether it's your fault or the students, check for plagiarism, email feedback, get scores for individual tests, and more!