Simple String Similarity Algorithm in JavaScript or, How to Tell if Two Strings are Similar, even if they aren’t exactly the same

This blog post is brought to you by the developer of BitBudget. BitBudget is an automated budgeting app for Android and iOS which syncs with your bank account and helps you avoid overspending. If you’d like to quit living paycheck-to-paycheck and get a better handle on your finances, download it today! https://bitbudget.io

At the moment I happen to be working on a personal finance app called BitBudget, where I need to be able to figure out if two purchases were made with the same merchant, or different merchants. For example, does a financial transaction labeled “VZWRLSS*PRPAY AUTOPAY 02/19 PURCHASE” represent a transaction with the same company as “VZWRLSS*PRPAY AUTOPAY 03/19 PURCHASE”? What about “CALM 03/26 PURCHASE” and “CALM 02/26 PURCHASE INTERNET”? Many transactions are easy to compare, “McDonald’s” vs “Amazon”, or “Chipotle Mexican Grill” vs “Starbucks”, but once banks and payment processors start throwing in all this extra information things get tricky.

While I personally am not really a computer science / algorithms kind of guy, sometimes you really need an algorithm to get the job done! So if you find yourself in the same boat I have your answer right here. After a quick google search on this topic I discovered that there appear to be three different types of string comparison algorithms:

  1. Edit Distance Based
  2. Token Based
  3. Sequence Based

If you’d like to read more about the three types of algorithm’s I suggest reading: String similarity — the basic know your algorithms guide!

For my use-case, I decided that an Edit Distance Based algorithm would be the quickest strategy to implement myself, so that’s what I’m going with and would like to present below. The actual code that I will end up using in my app may feature a few modifications for speed, such as shortening the number of iterations before returning a result, but what I have so far should be a good start if you need something quick and easy:

var string = [];
string[0] = 'CALM 03/26 PURCHASE';
string[1] = 'CANVA* 02644-3020257 03/28 PURCHASE HTTPSCANVA.CO DE';
string[2] = 'VZWRLSS*PRPAY AUTOPAY 03/19 PURCHASE';
string[3] = 'WWW.NORDVPN.COM HTTPSWWW.NORD';
var findMe = 'CALM 02/26 PURCHASE INTERNET';
function calculateSimilarity(aString, bString) {
var matchingCharacters = 0;
var totalCharacters;
if (aString.length >= bString.length) {
totalCharacters = aString.length;
} else {
totalCharacters = bString.length
}
var shortestStringLength;
if (aString.length < bString.length) {
shortestStringLength = aString.length;
} else if (bString.length < aString.length) {
shortestStringLength = bString.length;
} else {
shortestStringLength = aString.length;
}
for (var i = 0; i < shortestStringLength; i++) {
if (aString[i] === bString[i]) {
matchingCharacters++;
}
}
var percentSimilar = matchingCharacters / totalCharacters;
return percentSimilar;
}
console.log(calculateSimilarity(findMe, string[0]).toString());
console.log(calculateSimilarity(findMe, string[1]).toString());
console.log(calculateSimilarity(findMe, string[2]).toString());
console.log(calculateSimilarity(findMe, string[3]).toString());
 

Working with ISO 8601 dates in Python Part II

This blog post is brought to you by the developer of BitBudget. BitBudget is an automated budgeting app for Android and iOS which syncs with your bank account and helps you avoid overspending. If you’d like to quit living paycheck-to-paycheck and get a better handle on your finances, download it today! https://bitbudget.io

If you happen to have stumbled upon this post I apologize, I’m not going to be doing a lot of explaining here. Rather, I really just wanted to post this little snippet of code for my own reference so I don’t lose it! But hey, maybe you’ll find it useful too…

from datetime import date, datetime
now = datetime.now()
print(now)
now_iso_8601 = now.isoformat()
print(now_iso_8601)
import time as time_
current_time = time_.time()
print(current_time)
# date.isoformat() vs date.fromisoformat
date_from_iso_format = date.fromisoformat('1987-02-06')
print(date_from_iso_format)
date_isoformat = date.isoformat(now)
print(date_isoformat)
# REFERENCE: https://topherpedersen.blog/2019/07/12/how-to-get-the-current-year-month-and-day-as-integers-in-python-3-using-the-datetime-module/
# REFERENCE: https://www.w3schools.com/python/python_datetime.asp
year = now.year
month = now.month
day = now.day
print("One month ago...")
one_month_ago = date(year, month - 1, day)
print(one_month_ago)
print("One year ago...")
one_year_ago = date(year - 1, month, day)
print(one_year_ago)
print("Two years ago...")
two_years_ago = date(year - 2, month, day)
print(two_years_ago)
view raw date_playground.py hosted with ❤ by GitHub
 

How to Push a Previous Commit Back to the Top of the Master Branch in GitHub

This blog post is brought to you by the developer of BitBudget. BitBudget is an automated budgeting app for Android and iOS which syncs with your bank account and helps you avoid overspending. If you’d like to quit living paycheck-to-paycheck and get a better handle on your finances, download it today! https://bitbudget.io

Having trouble trying to push an old commit back to the top of your master branch in GitHub? This can be quite the doozy! I find myself frequently wanting to return my GitHub repository back to a previous state, and Git does not make this easy to do! What usually happens for me is that whenever I’m ready to finally push the previous commit back to the master branch, I end up running into a merge conflict. Ouch.

So, this is what you need to do if you find yourself in this situation. First, checkout the old commit that you want to restore your repository to (replace ‘c0mm1t1d’ with the commit id you want to checkout):

$ git checkout c0mm1t1d

Then create a new branch to work with:

$ git switch -c my-new-branch

$ git push origin my-new-branch

For good measure, make a small change to your new branch and commit the change. I suggest adding a comment or some other superficial change so you can verify that your repo has been updated exactly the way you like. Then commit the change:

$ git add -A

$ git commit -m "bug fix"

$ git push origin my-new-branch

Now time for the magic! We will merge our new branch back into the master branch using the “favor ours merge strategy” to ensure that our new branch is favored over the old branch should any merge conflicts arise:

$ git merge -s ours master

$ git checkout master

$ git merge my-new-branch

$ git push origin master

Alight, so there’s one last key piece of information I must mention: At some point you are going to be prompted to “Please enter a commit message to explain why this merge is necessary”, and then will get stuck inside of some awful vi/vim editor which you can’t get out of. Here’s what you need to do! Enter a short message explaining the merge, press ESCAPE, type:

:wq
Then press ENTER again to exit the prompt. And that’s it! Your repo and master branch are back in business.

 

Trouble getting Realm Version 5.0.0 to Work in React-Native? Here’s The Solution…

This blog post is brought to you by the developer of BitBudget. BitBudget is an automated budgeting app for Android and iOS which syncs with your bank account and helps you avoid overspending. If you’d like to quit living paycheck-to-paycheck and get a better handle on your finances, download it today! https://bitbudget.io

Welcome back dear internet friend!

So it looks like you’re having trouble getting Realm Version 5.0.0 in your React-Native app? It’s not your fault! For the past several hours I’ve found myself banging my head against the wall with the same problem, and here’s what I’ve discovered: Realm has not updated their JavaScript documentation to match version 5.

That’s right, while the documentation may “say” that it’s for version 5, as of April 2020 the code samples are all for version 4 and likely will not work if you’ve gone ahead and installed version 5. The fix for this is simple however. Just go ahead and uninstall version 5, and then install version 4 and all shall be well!

$ npm uninstall --save realm

$ npm install --save realm@4.0.0-beta.0

$ cd ios

$ pod install

$ cd ../

Then try running you’re app again…

$ npx react-native run-android

Furthermore, I think the reason behind this mistake by the Realm team is that they are primarily focused on iOS first, and Android second, and React-Native/NodeJS last! So if you are doing native iOS development you probably should be using version 5 if you’re starting a new project. But if you’re a React-Native or Node developer, you definitely want to be using version 4 until they updated their docs.

 

React Native UI Component Not Updating when Redux Store Changes

This blog post is brought to you by the developer of BitBudget. BitBudget is an automated budgeting app for Android and iOS which syncs with your bank account and helps you avoid overspending. If you’d like to quit living paycheck-to-paycheck and get a better handle on your finances, download it today! https://bitbudget.io

Having trouble getting your React Native UI components to update after the state of your Redux store has changed? Your problem is likely related to the brave new world of ES6 and the Functional Programming Paradigm. Specifically, in your Redux reducers you need to make sure you are keeping everything “immutable”. The simplest way to fix this if the spread operator (…) isn’t working for you is to try wrapping values that you wish to copy in JSON.parse and JSON.stringify methods. I know it’s very ugly, but it is an extremely effective method for fixing issues with React, Redux, and UI components that are failing to sync with state changes in your Redux store. For example, take a look at the two reducers below. The first example shows a broken reducer from one of my applications. And the second example shows the same reducer after I fixed it using the method described above:

Broken Reducer

const initialState = {
snacks: []
}
const logCaloriesReducer = (state, action) => {
// check for state undefined to prevent
// redux from crashing app on load
if (typeof state === 'undefined') {
return initialState;
}
switch(action.type) {
case 'LOG_CALORIES':
const updatedState = { ...state };
const indexOfNextSnack = updatedState.snacks.length;
const newSnack = {
calories: action.payload.calories,
time: action.payload.time
};
updatedState.snacks[indexOfNextSnack] = newSnack;
return updatedState;
default:
return state;
return state;
}
};
view raw broken_reducer.js hosted with ❤ by GitHub

Working Reducer

const initialState = {
snacks: []
}
const logCaloriesReducer = (state, action) => {
// check for state undefined to prevent
// redux from crashing app on load
if (typeof state === 'undefined') {
return initialState;
}
switch(action.type) {
case 'LOG_CALORIES':
const newState = JSON.parse(JSON.stringify(state));
const indexOfNextSnack = state.snacks.length;
const newSnack = {
calories: action.payload.calories,
time: action.payload.time
};
newState.snacks[indexOfNextSnack] = newSnack;
return newState;
default:
return state;
return state;
}
};
view raw working_reducer.js hosted with ❤ by GitHub
 

How to Build a Simple Web Server in Golang to Serve Static HTML Pages

This blog post is brought to you by the developer of BitBudget. BitBudget is an automated budgeting app for Android and iOS which syncs with your bank account and helps you avoid overspending. If you’d like to quit living paycheck-to-paycheck and get a better handle on your finances, download it today! https://bitbudget.io

Quick little demonstration of how to server static HTML pages using Golang. This example assumes both your index.html and webserver.go files are in the same directory:

// REFERENCE (Simple Static Web Server in Go): https://stackoverflow.com/questions/26559557/how-do-you-serve-a-static-html-file-using-a-go-web-server
package main
import (
"net/http"
)
func main() {
http.Handle("/", http.FileServer(http.Dir("./")))
http.ListenAndServe(":3000", nil)
}
view raw webserver.go hosted with ❤ by GitHub
<!DOCTYPE html>
<html>
<body>
<h1>My Super Sweet Homepage</h1>
<button onclick="doStuff()">CLICK HERE</button>
<script>
function doStuff() {
alert("do stuff!");
}
</script>
</body>
</html>
view raw index.html hosted with ❤ by GitHub

Need routes to other pages? Check out this example I have posted on GitHub: SimpleGolangWebServer

Need to serve up JSON instead of HTML? Check out this example by Tom Hudson: simple-json-api.go

 

The Best React-Native/Redux Tutorial

This blog post is brought to you by the developer of BitBudget. BitBudget is an automated budgeting app for Android and iOS which syncs with your bank account and helps you avoid overspending. If you’d like to quit living paycheck-to-paycheck and get a better handle on your finances, download it today! https://bitbudget.io

This post is sort of just a bookmark for myself, as I know I will undoubtedly need to reference the React-Native/Redux boilerplate for years to come. However, maybe someone else out there on the internet will find this helpful as well! TLDR: Aligator.io has the best quickstart tutorial with all of the boilerplate code that you need to get up and running with Redux in a React-Native project.

Now for some more opinion and a quick rant: All of the boilerplate code that is necessary to get up and running with Redux is its biggest drawback. Personally, I hate boilerplate code. Maybe that’s because I’m a pretty messy and disorganized person, but I can’t stand having to write and learn tons and tons of boilerplate code just to get started with something. Take the Django web framework for instance. The first Python web-dev project I ever undertook I initially turned to Django after coming from a PHP background. But after 4 pages of “Getting Started” material I still had not gotten to “hello, world.” So I ended up ditching Django in favor of the much simpler Flask web framework, and haven’t looked back since.

With Redux I find myself in a similar predicament. I need some sort of state management for my React projects as the built in system just isn’t cutting it anymore, but is Redux really the best option? A much simpler solution is Unstated. So if you’ve made it this far in my post and are having similar feelings, I suggest checking out Unstated.

The only problem with Unstated is that employers are probably using Redux (or possibly MobX-State-Tree). So you kind of have to learn it, just because that’s what everyone seems to be using. In essence, I don’t think Redux is so bad. Actions, reducers, and a store. Pretty straight forward right? It sounds simple, but in practice it’s probably the most painful part of programming in React.

 

* What went wrong: Execution failed for task ‘:app:validateSigningDebug’. > Keystore file ‘debug.keystore’ not found for signing config ‘debug’.

This blog post is brought to you by the developer of BitBudget. BitBudget is an automated budgeting app for Android and iOS which syncs with your bank account and helps you avoid overspending. If you’d like to quit living paycheck-to-paycheck and get a better handle on your finances, download it today! https://bitbudget.io

Having trouble running getting your React Native app to run? Haven’t worked on it in a month or two? Now you’re running into this error about debug.keystore not found? Fret not dear internet friend! Here are some solutions that may help.

I personally ran into this error after cloning a previous version of an app that I was working on from Github. Like you, I ended up trying many different things to fix this problem. However, I’m not sure if any of the steps I performed prior to stumbling upon a good solution were necessary. But just to make sure, I’m going to include some of the steps that I took before getting my app to work again in case any of these steps may be helpful or necessary to anyone else out there on the internet.

First I installed all of my node packages with npm…

$ cd MyAwesomeReactNativeApp 

$ npm install 

After installing all of my node dependencies I then attempted to run the app for the first time and ran into the error message described above. My first attempt at fixing the problem involved attempting to reinstall all of my native Android dependencies with gradle…

$ cd android

$ ./gradlew build --refresh-dependencies

$ ./gradlew clean

I’m not sure if this is ever necessary for Android like it is for iOS with cocoapods and pod install, but it is something I did, but it probably didn’t actually do anything and likely wasn’t necessary.

Next, I attempted to create a new debug.keystore file myself using the following terminal commands:

$ cd android/app

$ keytool -genkey -v -keystore debug.keystore -storepass android -alias androiddebugkey -keypass android -keyalg RSA -keysize 2048 -validity 10000

Unfortunately this didn’t actually work! But what did work was importing my project into Android Studio, cleaning the build folder from within Android Studio, and then running the app on the built-in Android emulator instead of my actual Android device. Please note that I was prompted with an error message when running the app on the simulator that Android Studio wanted to delete the previous version of the app installed on my emulator, so please make sure to do this if your are prompted for something similar.

Also, please note that I deleted the old version of my app from my physical phone before attempting to run the app on my personal device as well. However, this was not sufficient to solve the problem. In conclusion, you need to make sure you delete any old versions of the app that were signed with old keys from your emulator or device AND then use Android Studio to clean your build folder and run the app. In my case, I believe Android Studio handled fixing all of the issues related to the mismatched debug.keystore files behind the scenes for me, so if you are stuck on this, I suggest you let Android Studio fix the problem for you as well.

Hope you found this blog post helpful.

@topherPedersen

P.S. This was the first time I worked on this particular app since publishing it on the Google Play Store. So signing the production release of the app was probably a big part of the problem as well. Whatever the exact cause, the steps above should fix the issue.

 

App Store Binary Rejected: Guideline 4.2 – Design – Minimum Functionality

This blog post is brought to you by the developer of BitBudget. BitBudget is an automated budgeting app for Android and iOS which syncs with your bank account and helps you avoid overspending. If you’d like to quit living paycheck-to-paycheck and get a better handle on your finances, download it today! https://bitbudget.io

Was your app recently rejected from Apple’s App Store due to minimal functionality or content under guideline 4.2? You’re not alone! On this episode of Misadventures in Startups I talk about my own experience with the arbitrary and fickle nature of Apple’s App Store review process, and suggest a possible solution: Cross Platform Application Develop for Android, iOS, and the Web with ReactJS & React-Native. Are Google or Apple’s monopolistic policies over mobile application distribution getting in your way? Facebook Inc. has a tool for that.

 

How to Strip Newline Characters from a String in Golang

This blog post is brought to you by the developer of BitBudget. BitBudget is an automated budgeting app for Android and iOS which syncs with your bank account and helps you avoid overspending. If you’d like to quit living paycheck-to-paycheck and get a better handle on your finances, download it today! https://bitbudget.io

Having trouble stripping newline characters from a string in Golang? The easy way I’ve found is to use strings.Replace. Also, make sure to see the “gotcha” involving runes below the example code. Sometimes you will need to change the “/n” character to the newline rune “/r/n”.

package main
import (
"fmt"
"strings"
)
func main() {
var string_a string = "My super \nsweet \nstring has \nmany newline\n characters"
fmt.Println(string_a)
var string_b string = string_a
string_b = strings.Replace(string_b, "\n", "", -1)
fmt.Println(string_b)
}
view raw strip_newline.go hosted with ❤ by GitHub

However, beware of this gotcha involving runes. I’m still a newbie Golang coder so I don’t fully understand all of the differences between strings, bytes, runes, and characters, but sometimes the code above will not work. Instead, of stripping the newline character “/n”, you’ll need to strip the newline rune “/r/n”. In this case, your code will look something like:

string_b = strings.Replace(string_b, "\r\n", "", -1)