Skip to content

Latest commit

 

History

History
107 lines (80 loc) · 4.19 KB

CHRISTIAN_DUMAS.md

File metadata and controls

107 lines (80 loc) · 4.19 KB

Stock Alert in Racket

Christian Dumas

April 30, 2017

Overview

This set of code allows an individual to perform several actions on stock values.

Using Yahoo finance, a list of stock tickers can be made which periodically sends updates of increases or decreases (negative increases).

You can also quickly send immediate values, or view immediate values through the GUI.

Authorship note: All of the code described here was written by myself.

Libraries Used

The code uses four libraries:

(require net/url)
(require xml)
(require html)
(require (prefix-in goo: racket/gui))
  • The net/url library provides the ability to make queries to the Yahoo Finance API.
  • The xml library is used to allow access to xml utilities to access the stock values.
  • The html library is also used to parse stock values.
  • The racket/gui library is used to access timer constructs.

Key Code Excerpts

Here is a discussion of the most essential procedures, including a description of how they embody ideas from UMass Lowell's COMP.3010 Organization of Programming languages course.

Four examples are shown and they are individually numbered.

1. Map to parse fairly arbitrary data into strings.

The following code gets and fully parses a list of stock values as a list of strings.

(define (get-stock-values stksymbol)
  (map cadr (cdadr (csv->sxml (pcdata-string (car (read-html-as-xml (get-pure-port (string->url (string-append "http://download.finance.yahoo.com/d/quotes.csv?s=" stksymbol "&f=bop"))))))))))

It takes a string input.

2. Initialization using a Global Object

This procedure produces a "stock-list" object which has the shown local procedures.

(define (make-stock-list)
  (let ((stocklst (list))
        (stocksend #f)
        (lastsend (current-seconds)))
    (lambda (command . opt)
      (cond [(eq? command 'add_stock) (set! stocklst (append stocklst (list (cons (first opt) (get-stock-values (first opt))))))]
            [(eq? command 'remove_stock) (set! stocklst (remove (first opt) stocklst (lambda (x y) (equal? x (car y)))))]
            [(eq? command 'toggle_send) (if stocksend (set! stocksend #f) (set! stocksend #t))]
            [(eq? command 'send?) stocksend]
            [(eq? command 'get_list)  stocklst]))))

3. Interfacing with the GUI

This code was partially written by each of us, and is the central stitchings to combine front and back end.

Each of these functions is called by his gui, and my stock list object uses values to determine what to do.

(define (add_stock a)
  (begin (stock_list 'add_stock (htdp:text-contents text_box)) #t))
(define (remove_stock a)
  (begin (stock_list 'remove_stock (htdp:text-contents text_box)) #t))
(define (view_purchase a)
  (begin (htdp:draw-message i (first (get-stock-values (htdp:text-contents text_box)))) #t))
(define (view_open a)
  (begin (htdp:draw-message i (second (get-stock-values (htdp:text-contents text_box)))) #t))
(define (view_close a)
  (begin (htdp:draw-message i (third (get-stock-values (htdp:text-contents text_box)))) #t))
(define (send a)
  (begin (send-txt (htdp:text-contents text_box)) #t))
(define (set_auto a)
  (begin (stock_list 'toggle_send) #t))

4. Mapping to print values which fit a criteria.

The following code is our stock checking algorithm.

It simply triggers an event each timer tick that checks the entire stock list to see if any of the values have changed by the desired amount.

(define (check_stocks)
  (if (stock_list 'send?) (map (lambda (x) (if
                                            (> (first (get-stock-values (first x)))
                                               (* (second (first (member
                                                                  (first x)
                                                                  (stock_list 'get_list)
                                                                  (lambda (findval listval) (equal? findval (first listval))))))
                                                  1.1)) (send-txt (first x)) 0)) (stock_list 'get_list)) 0))

(define timeguy (new goo:timer% [notify-callback check_stocks]
                                [interval 1000]
                                [just-once? #f]))