How to Use Python With Real-Time Data and REST APIs

We take a look at how to use Python and a freely available REST API to call, manipulate, and display data on our machine.

Carlos F. Enguix

Mar. 18, 19 · Tutorial

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Python Tutorial

1. Introduction

The Forex Quote API provided by 1forge.com is one of the most generous places with free plans to get real-time currency exchange values. The https://1forge.com/forex-data-api site includes an introduction to the Forex data API.

For free accounts, the REST rate limit is 1000 requests per day returning results in JSON format. It supports more than 700 currency pairs. Unfortunately, the Peruvian Sol (PEN) is not supported.

You have to obtain an API key to submit requests. For that, you can register at https://1forge.com/register and, finally, in your free account, you can get your API key.

In order to learn which data type is returned, you can submit a raw request via your favorite web browser, including the currency pairs and your API key, such as:

https://forex.1forge.com/1.0.3/quotes?pairs=EURUSD,GBPJPY,AUDUSD&api_key="your_api_key"

[{"symbol":"EURUSD","bid":1.12333,"ask":1.12335,"price":1.12334,"timestamp":1552081127},
 {"symbol":"GBPJPY","bid":144.677,"ask":144.683,"price":144.68,"timestamp":1552081127},
 {"symbol":"AUDUSD","bid":0.70454,"ask":0.70456,"price":0.70455,"timestamp":1552081127}]

As you can see, the REST call returns a list of key values.

Please note that I am not using the Python client. Instead, I am using REST calls to the API. Also please note that over the weekends there are no currency updates via this API, as compared to other sites such as the XE currency converter.

REST API calls include (taken from the Forex site):

2. Analysis of Code Excerpts

In this case, I am working with a Python script that gets the currency exchange values of Euros compared to US Dollars and vice-versa. The code executes a REST request for getting the respective quotes.

2.1 Initial Code: Import Statements and Global Variables

import requests
import json
import datetime
from tkinter import *
import time

api_key = "your_api_key"
pairs = "EURUSD,USDEUR"
url = "https://forex.1forge.com/1.0.3/quotes?pairs=" + pairs + "&api_key=" + api_key

In this first code excerpt, we import the required libraries and set up the API key and the currency pairs to form the final URL where we'll send the REST request.

2.2 Get Currency Values Code Excerpt

def get_currency_values():
    """
        Returns currency pair values
        :return: currency pair values.
        Example EURUSD 1.1239 (euro to dollar conversion)
    """

    response = requests.get(url)

    data = response.text
    currencies = json.loads(data)
    forex_currencies = []

    for currency in currencies:
        for key, value in currency.items():
            if key == "symbol":
                symbol_from = value[:3]
                symbol_to = value[3:]
                str_currency = symbol_from + " TO " + symbol_to + ": "
            if key == "price":
                price = value
        forex_currencies.append(str_currency  + str(price))

    return forex_currencies

In this code snippet, we process the raw REST request and format it into a list of currency pairs with its respective values: for instance EUR to USD: 1.12329

2.3 Set Up GUI Window Elements

In the code excerpt depicted below, we set up the GUI Window with three labels, one containing the date/time and other labels depicting currency pair values. In this case Euro to Dollar and Dollar to Euro, the script can be customized to include the required currencies (may require you to add labels to the main window).

def setup_gui(window, symbol_pairs):
    """
        Returns a window with labels representing currency pairs information (prices)

        :param window: window to be setup with labels
        :param symbol_pairs: the symbol pairs with associated currency values
        :return: Returns a window with time, and currency pairs with associated currency values
    """

    window.wm_title("Currency Table")

    date_time = datetime.datetime.now().strftime("%A %d %B %Y %H:%M:%S:%f")
    str_date_time = "On " + str(date_time)

    l1 = Label(window, text=str_date_time)
    l1.grid(row=0, column=0)

    l2 = Label(window, text=symbol_pairs[0])
    l2.grid(row=1, column=0)

    l3 = Label(window, text=symbol_pairs[1])
    l3.grid(row=2, column=0)

    screen_width = window.winfo_screenwidth()
    screen_height = window.winfo_screenheight()

    # currency window info positioned on the lower right side of the screen
    # and with a given screen width and height
    xpos = screen_width - 250
    ypos = screen_height - 150
    window.geometry("250x75+" + str(xpos) + "+" + str(ypos))

    return window

2.4 Code Excerpt Setting Up A Top Window With Date/Time & Currency Pairs Values

Finally, we set up the window so that currency information is always showing at the top of other windows:

def main():    
    while True:
        window = Tk()
        symbol_pairs = get_currency_values()
        window = setup_gui(window, symbol_pairs)        
        window.update()        

        # let the window be always on top of other windows        
        window.lift()        
        window.attributes('-topmost', True)        

        # we get the next currency pair values every 60 seconds        
        time.sleep(60)        
        window.destroy()

if __name__ == '__main__':    
    main()

3. Whole Code Script

And this is the whole Python script:

import requests
import json
import datetime
from tkinter import *
import time


api_key = "your_api_key"
pairs = "EURUSD,USDEUR"
url = "https://forex.1forge.com/1.0.3/quotes?pairs=" + pairs + "&api_key=" + \
      api_key


def get_currency_values():
    """
        Returns currency pair values
        :return: currency pair values.
        Example EURUSD 1.1239 (euro to dollar conversion)
    """

    response = requests.get(url)

    data = response.text
    currencies = json.loads(data)
    forex_currencies = []

    for currency in currencies:
        for key, value in currency.items():
            if key == "symbol":
                symbol_from = value[:3]
                symbol_to = value[3:]
                str_currency = symbol_from + " TO " + symbol_to + ": "
            if key == "price":
                price = value
        forex_currencies.append(str_currency  + str(price))

    return forex_currencies


def setup_gui(window, symbol_pairs):
    """
        Returns a window with labels representing currency pairs information (prices)

        :param window: window to be setup with labels
        :param symbol_pairs: the symbol pairs with associated currency values
        :return: Returns a window with time, and currency pairs with associated currency values
    """

    window.wm_title("Currency Table")

    date_time = datetime.datetime.now().strftime("%A %d %B %Y %H:%M:%S:%f")
    str_date_time = "On " + str(date_time)

    l1 = Label(window, text=str_date_time)
    l1.grid(row=0, column=0)

    l2 = Label(window, text=symbol_pairs[0])
    l2.grid(row=1, column=0)

    l3 = Label(window, text=symbol_pairs[1])
    l3.grid(row=2, column=0)

    screen_width = window.winfo_screenwidth()
    screen_height = window.winfo_screenheight()

    # currency window info positioned on the lower right side of the screen
    # and with a given screen width and height
    xpos = screen_width - 250
    ypos = screen_height - 150
    window.geometry("250x75+" + str(xpos) + "+" + str(ypos))

    return window


def main():

    while True:

        window = Tk()
        symbol_pairs = get_currency_values()
        window = setup_gui(window, symbol_pairs)
        window.update()

        # let the window be always on top of other windows
        window.lift()
        window.attributes('-topmost', True)

        # we get the next currency pair values every 60 seconds
        time.sleep(60)
        window.destroy()


if __name__ == '__main__':
    main()

4. Setting Up Automatic Script Execution in a Windows 10 Environment

The final step is to rename the file to "forex.pyw" (or any name you want, really; just make sure to end the name of the file with the ".pyw" extension, because it is a GUI application):

pythonw.exe forex.pyw

This is the final resulting window that appears on top of other windows and changes the currency values every 60 seconds:

If you are running this script on Windows, you can enable the automatic execution of the script when logging in to your user account, by following these steps:

Press the Windows Button + R
Open the Startup Window: "shell:startup"

Create a Windows link in "C:\Users\YourUserName\AppData\Roaming\Microsoft\Windows\Start Menu\Programs\Startup with the following properties:

Target: C:\Anaconda35\pythonw.exe forex.pyw (this is my Anaconda Python installation and the Python script which is found in the "Start in" directory).
Start in: C:\Users\YourUserName\PycharmProjects\forex (is the directory where my script is).

Given that I am no Linux expert I am not sure if you can run an equivalent "cron job."

For those that require continuous information about real-time currency exchange values, this Python script will be really helpful.

REST Web Protocols Python (language) Data (computing)

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