Churning Data into Information

I work with a lot of data on the behalf of an agency without a lot of money. Exploring free-to-use and open-source tools is key to being effective in my job.

Recently, I’ve written a a couple of series on how to use R and SQL to sort through Homeless Management Information System data.

These data are essential to local governments helping individuals experiencing homelessness to be housed quickly and appropriately.

But one area R and SQL have not delivered is on-line interactive dashboards. Data is one thing, but easy to digest information is really key to informing stakeholders how the system is working to end homelessness.

In other projects I’ve attempted to generate graphs as images and upload to a static link. Then, each time the data change re-generate replace the image. But, most website servers cache the images so it is not ideal.

This has pushed me to try to learn D3.

I’m not going to lie, I’ve felt confused by languages, IDEs, and libraries. And I’ve overcome most of the these challenges. But I’ve never been so confused as by the layout and syntax of D3. The dyslexic feeling I get trying to work in D3 has discouraged me from spending too much time on it.

But recently I decided to take another stab at it– this time I lucked out and found the C3.js.

Essentially, C3 is a library which greatly simplifies D3. It boils down building a graph into a set of options passed to the C3 graph builder as a JSON object.

This code:

var chart = c3.generate({
    data: {
        x: 'Date',
        y: '# Individuals',
        xFormat: '%Y-%m-%d',
        url: 'https://ladvien.com/projects/d3/data/trendsInTX601.csv',
        type: 'line',
        // colors: {
        //     Count: '#990000'
        // }
        names: {
            NumberHomeless: "Homeless",
            NumberInRRH: "Rapid Rehousing",
            NumberInPSH: "Permanent Supportive Housing"
        }
    },
    
    title: {
        text: "Homeless or Formerly Homeless in TX-601"
    },

    legend: {
        show: true
    },

    axis: {
        x: {
            type: 'timeseries',
            tick: {
                count: 4,
                format: '%Y-%m-%d',
                // rotate: 90,
                multiline: false,
                
                culling: {
                    max:5 
                }
            }
        },
        y: {
            max: 3000,
            min: 0,
            label: "# Individuals"
            // Range includes padding, set 0 if no padding needed
            // padding: {top:0, bottom:0}
        },
    },
    
    point: {
        r: 0
    }
});

Using this CSV:

Produces the following graph:

One Hiccup

I did run into a one hiccup in setup. It seems the most recent version of d3 (version 4.0) has had much of its API overhauled. In such, it will not work with C3. But D3 v3 is still available from the D3 CDN:

<script src="https://d3js.org/d3.v3.min.js"></script>

Calling this library and following the instructions outlined by the C3 site, you can be generating graphs in little time.

Updating Data Securely and On Schedule

Now that I’ve the ability to use R and SQL to sort through my data, and I could quickly generate graphs using D3 and C3, it’d be really nice if a lot of this could be automated. And luckily, I’d run into a few other tools which made it pretty easy to replace the data on my C3 graphs.

Rsync

Rsync is primarily a Linux tool, but it is available on Windows as well. It is nice since it will allow you to quickly reconcile two file-trees (think of a manual Dropbox).

It will also allow you to sync a local file tree with a server file tree across an SSH connection. For example, I use the following command to sync the data mentioned above to the server

rsync -avz /Users/user/data/js-practice/d3/* ladvien@ladvien.com:/usr/share/nginx/html/projects/d3/

After running this command it will prompt for a password to access the server. Then, it will proceed to sync the two file-trees. Nifty!

This allows me to quickly update the data on the graph. Now, if only there were a way to automatically insert my password, then I could write a script to automate the whole process.

Python Keyring

Python Keyring is a tool which allows you to save and retrieve passwords from your PC’s keyring.

It is compatible with:

  • Mac OS X Keychain
  • Freedesktop Secret Service (requires secretstorage)
  • KWallet (requires dbus)
  • Windows Credential Vault

If you have Python installed you can install the Keyring tool with Pip:

$pip install keyring

After, you can store a password in the keyring by using the command-line tool. You will need to replace username with the name of your server login.

$keyring set system username

And retrieve it with:

$keyring get system username

This is great. It means we can store our password in the keyring and retrieve it securely from a script.

Great! Now we could write a script to have Rsync sync the any data changes locally with the server. Right? Well, almost. We needed one more tool.

SSHPass

There is a problem with using Rsync to sync files remotely from a script. When Rsync is called from a script it will not wait for parameters to be passed to the tool. Sigh.

Luckily, I’m not the only with this problem and a tool was created to solve this problem.

If you are on a Mac you’ll need to use Brew to install SSHPass.

brew install https://raw.githubusercontent.com/kadwanev/bigboybrew/master/Library/Formula/sshpass.rb 

There we go! Now we can automate the whole process.

I wrote this script to do the dirty work:

#!/bin/sh
PASSWORD=("$(keyring get system ladvien.com)")
ECHO ""
ECHO "****************************"
ECHO "* Updating D3 Projects     *"
ECHO "****************************"
ECHO ""
sshpass -p "$PASSWORD" rsync -avz /Users/user/data/js-practice/d3/* root@ladvien.com:/usr/share/nginx/html/projects/d3/

Cron

Ok! One last bit of sugar on this whole process. Let’s create a Cron job. This will run the script in the background at an interval of our choosing.

For me, I’ve a staff who pulls data and runs a master script every Monday. So, I’ll set my automated script to update my C3 graph data on Tuesday, when I know new data is available.

You can use Nano to edit your Cron job list.

env EDITOR=nano crontab -e

To run a Cron job on Tuesday we would set the fifth asterisk to 2.

* * * * 2 /the/path/to/our/update_script.sh

And don’t forget to make the update_script.sh executable.

chmod +x update_script.sh

I’m a hacker hacking with a hacksaw!

Setup Headless WiFi on Re4son's Kali Pi

I bought a few Raspberry Pi Zero W’s for $10. It was happenstance I also purchased the Udemy course Learn Ethical Hacking from Scratch. I figure, I might as well put these things together.

I also discovered the Sticky Fingers Kali Pi kernel and distros put together by Re4son.

It has worked well so far. However, I’ve not fully tested the Bluetooth LE hardware on the custom kernel.

One of the issues I’ve had is not being able to connect to new hotspots headlessly. Usually, you’d boot the rp0w connected to a monitor, keyboard, mouse, and edit wpa_supplicant.conf directly. But what if you want to go into a new location with only your laptop and the rp0w. How would you add the wifi credentials to the rp0w without a monitor, etc.

For awhile, I tried to get the ethernet gadget setup to work on the rp0w without any luck. I think the problems relates to trying to use the gadget hardware on a Mac rather than a Windows machine.

In the end, I decided I would add a script which would do the following:

  1. Mount the /boot partition (which is editable through PC’s SD card reader).
  2. Look for a file on the /boot called “wpa_supplicant.txt” and copy it to the /etc/wpa_supplicant.conf
  3. Look for a file on the /boot called “interfaces.txt” and copy it to the /etc/networks/interfaces
  4. Unmount /boot
  5. Remove the /boot directory

I saved this script in /root as wifi_setup.sh. I then added a call to it in /etc/rc.local

#!/bin/sh -e
#
# rc.local
#
# This script is executed at the end of each multiuser runlevel.
# Make sure that the script will "exit 0" on success or any other
# value on error.
#
# In order to enable or disable this script just change the execution
# bits.
#
# By default this script does nothing.
/root/wifi_setup.sh || exit 1
exit 0

Here’s the wifi_setup.sh

#!/bin/bash

if [ ! -d "/boot" ]; then
        echo 'Mounting /boot'
        cd ..
        mkdir /boot
        mount /dev/mmcblk0p1 /boot
fi

if [ -f "/boot/wpa_supplicant.txt" ]; then
        echo 'Applying wpa_supplicant'
        cp /boot/wpa_supplicant.txt /etc/wpa_supplicant.conf
        mv /boot/wpa_supplicant.txt /boot/wpa_supplicant.applied.txt
fi

if [ -f "/boot/interfaces.txt" ]; then
        echo 'Applying intefaces'
        cp /boot/interfaces.txt /etc/network/interfaces
        mv /boot/interfaces.txt /boot/interfaces.applied
fi

umount /boot
rm -r /boot

This has let me add a new network from my laptop with merely an SD card reader.

HMIS, R, SQL -- Work Challenge Three

Creating a Data Error Report by User

In this work challenge we will combine Client and Enrollment data, then we will add a non-HMIS dataframe which contains user account information. After these data are merged, we will then parse them for missing data elements and provide a by-user list of data errors.

Data Needed

As stated above, the data needed are:

  1. Client.csv
  2. Enrollment.csv
  3. A dataframe containg HMIS user contact info.

The key to this challenge literally is at the end of every HMIS CSV. Each exported CSV contains some metadata which describes how the data were produced.

The DateCreated should represent when the respective row was actually entered into the HMIS. DateUpdated is the last time that row was modified and saved in the HMIS. The UserID is the case-manager who last modified these data. Lastly, the ExportID is the number which identifies a collection of HMIS CSVs to be in the same batch.

We are going to focus in on the UserID element. Notice, you will not find the usernames, real names, email address, or really any contact information for individual HMIS users. However, having a unique user ID in each CSV would still allow HUD to use internal validity tests to determine the reliability of the user.

For us, we are going to take another source of data containing all of the UserIDs and contact information for the users. Now, this will probably be different each HMIS software vendor. But each vendor should have a way to export a list of the users in the system with their UserID, which will allow us to join these data to the HMIS CSVs.

For those participating in the work challenge from my CoC, I’ll provide a CSV with these user data.

After actual user names are joined to the CSVs, then we will begin to parse the CSVs for data errors. If you aren’t yet familiar with the term parse in computer science, think of it as diagraming a setence where we make the computer do all the work. Instead of a sentence, we will be diagraming a row of data to determine if there are any errors.

What’s an HMIS Data Error?

The HMIS Data Dictionary is specific about what a data error is.

  • 8 – Client doesn’t know
  • 9 – Client refused
  • 99 – Data not collected
  • Blank
  • Incomplete response
  • Non-determinable response

Here’s an example of a Client.csv which contains one of each type of error.

PersonalID FirstName LastName DOB SSN DisablingCondition VeteranStatus
ZP1U3EPU2FKAWI6K5US5LDV50KRI1LN7   Tesa 2010-01-01 123-45-6789 1 8
IA26X38HOTOIBHYIRV8CKR5RDS8KNGHV Fela Falla 1999-1-1 4321 1 1
LASDU89NRABVJWW779W4JGGAN90IQ5B2 Sarah Kerrigan   Blahblah 99 0

Here are the data errors:

  1. Tesa is first name blank
  2. Sarah’s DOB is blank
  3. Fela’s SSN is an incomplete response (must be 9 digits)
  4. Sarah’s SSN is non-determinable
  5. Sarah’s DisablingCondition was not collected.
  6. Tesa refused to provide a VeteranStatus.

The Goal

We are going to take a HMIS data and join it with a dataframe containing end-user information. Then, we will create a query to subset the dataframe so we get a dataframe which contains only rows with data errors. Lastly, we will get counts of the types of data errors and the names end-users who’ve caused the most data errors.

The data elements we will look into for errors:

  1. FirstName
  2. LastName
  3. DOB
  4. VeteranStatus
  5. DisablingCondition
  6. RelationshipToHoH

To get this information we will need to do the following:

  1. Load Client.csv, Enrollment.csv, and Users.xlsx
  2. Left join the clientDf and enrollmentDf.
  3. Left join the usersDf to the result of step 2.
  4. Parse the data elements listed above for data errors
  5. Create a dataframe which contains only rows with data errors
  6. Use the SQL Count function to count the number of data errors by the element list above.
  7. Use the SQL Count function to count how many times a end-users name is associated with a row containing errors.
  8. Create a dataframe of these counts
  9. Save the dataframe containing the error counts into an Excel file (.xlsx)

The Resources

Below are the resources which should help for each step:

TBD

Working with R Excel Libraries

We’ve worked a bit with Comma Separated Values (.csv) files, but it they aren’t the only way to store data. There are a lot of data storage formats, each with its strengths and weaknesses. One of the deficits of the CSV format is it cannot store formatting or graphs. This is the reason Excel format (.xls or .xlsx) has become another industry standard.

Excel is a program created by Microsoft to allow people to easily work with spreadsheets. With it, they created a way of storing data which allows for formatting and other information to be included. In fact, Excel documents have become so sophisticated programmers can include entire programs within the document. This is the reason you’ll often get the “Enable Content” button when open Excel document. That means there is some code embedded in the Excel document which will run if you say “Enable”. (Be careful, malicious programmers can insert code which could royally blink up your computer.)

When working with HMIS data being able to load and write Excel documents is necessary. Unfortunately, it adds a lot of complexity.

There are several R libraries which will allow us to work with Excel documents in R. They have different strengths, therefore, I’ll focus on two libraries, rather than one.

Installing R Libraries for Excel

Installing either of these libraries should be as simple as running the following code:

install.packages("XLConnect", dependencies=TRUE)
install.packages("openxlsx")

However, there are lots of ifs. Both of these libraries rely on the rJava library. Unfortunately, there is often some mismatch of computer architecture. What does that mean? Well, often you’ll install R for amd64, but rJava is easiest to get working with R for i386.

Just know, RStudio has a way to set the version of R you are using by going to Tools then go to Global Options. If you are in Windows, at the top of the R General section you will see the option to change your R version. If you are having difficulty getting the above Excel documents working, try switching the R version to i386. (Don’t forget to restart RStudio after switching.)

Past this, I’d be more than happy to help you troubleshoot. Just leave a comment below or shoot me an email. However, it can get pretty hairy–especially on a Mac.

Working with XLConnect

Now days, I only use XLConnect to load data from Excel sheets. I’ve just been too lazy to re-write all my code to use one library (which would be openxlsx). It’s my opinion the reason to use XLConnect is it’s a little easier to understand how it loads data. Its weakness is it doesn’t have as much flexibility in formatting Excel documents to be saved on your computer. And it can be confusing to save Excel sheets.

Loading Data from Xlsx Documents

Loading data using XLConnect is a little different than using the read.csv function. Like I stated earlier, Xlsx documents contain other information besides data. One critical piece of information is the sheet number.

Unlike CSVs a single Excel document can contain multiple spreadsheets. Each of these sheets will be broken out in tabs when you open an Excel document

XLConnect doesn’t make any assumptions, it wants you to tell it which sheet you’d like to load.

Here’s how to load an Excel document, the first sheet, in XLConnect:

library(XLConnect)
excelDf <- readWorksheetFromFile("/Users/user/Data/VI-SPDAT v2.0.xlsx", sheet = 1, startRow = 1)

It is similar to the read.csv() function, but notice the file in the path refers to VI-SPDAT v2.0.xlsx? You want to make sure your file format is either .xlsx or .xls as the readWorkSheetFromFile() function only works with Excel documents.

Also, there are two other parameters. The first, sheet = 1 is telling XLConnect to read in only the first sheet. Just know, you could set it to whatever sheet number you’d like. And for reference, the sheets are 1, 2, 3, 5…etc., left to right when opened in Excel. So, even if your sheets have different names XLConnect will still load the data respective to their numerical order.

The second parameter is startRow = 1. This allows you to tell R where to start the dataframe. For example, if you had a header in your Excel document which didn’t contain data.

We could skip down to row three, where the column headers are, by telling XLConnect startRow = 3.

Writing a Dataframe to Excel Document

Writing Excel documents are a little more complex–and one reason I’m not a huge fan of XLConnect.

Here’s how you’d write an Excel file:

######################### Data ###################################
###################### DO NOT CHANGE #############################
peopleDf <- data.frame(PersonalID=c("ZP1U3EPU2FKAWI6K5US5LDV50KRI1LN7", "IA26X38HOTOIBHYIRV8CKR5RDS8KNGHV", "LASDU89NRABVJWW779W4JGGAN90IQ5B2"), 
                       FirstName=c("Timmy", "Fela", "Sarah"),
                       LastName=c("Tesa", "Falla", "Kerrigan"),
                       DOB=c("2010-01-01", "1999-1-1", "1992-04-01"))
##################################################################
##################################################################

# Create a workbook to contain the worksheet(s).
peopleWorkbook <- loadWorkbook("People.xlsx",  create = TRUE)
# Create and name the worksheet.
myPeopleWorksheet <- createSheet(peopleWorkbook, "My People")
# Add the data to the worksheet, put it in the workbook, save it to the computer.
writeWorksheetToFile("People.xlsx", data = peopleDf, sheet = "My People")

After running this code you should have a file called People.xlsx in your working directory (remember, getwd() will tell provide the working directory). If you open this file, it should look something like this:

This looks a little complex, but it’s just because XLConnect makes it look complex. Here’s what it is is doing:

  1. A workbook is created, which is a place where worksheets can be stored.
  2. myPeopleWorksheet is created inside the workbook created above. The sheet is called “My People”
  3. The worksheet has our peopleDf added to it, then it is saved as a file called “People.xlsx” in our working directory.

Like I said, it’s a lot of unneeded complexity, in my opinion.

Why use Excel Documents

After the added complexity of reading and saving Excel documents you might wonder what the benefit is? Great question.

As stated at the beginning, Excel documents can contain other information besides just data. It contain formatting, images, graphs, and a lot of other stuff. And one of the reasons for writing report scripts is to automate all redundant tasks.

Imagine, you’ve got a data set of 12,000 participant enrollments. You want to create a spreadsheet which puts the enrollment in descending order. And you want to create this report daily.

If you used the write.csv() you would need to open the CSV after creating it, then manually add the sort to the document, save it as an Excel file, then send it out. I guarantee, after doing that for several weeks you are going to want to find a way to automate it. Especially, if you decide the headers need to have font size 18 as well.

Excel documents allow us to store the formating tweaks and XLConnect allows us to insert them automatically.

Adding formatting can get a little more complex and will be the focus of another article. Also, we will use openxlsx as it is much easier to output formatting, again, just my opinion.

Comparing Values in R and SQL

Comparative Functions

Comparing two or more values is an extremely important concept when talking to computers. In writing a report script, it is is essential. Comparisons allow us to filter to values within a range, allowing us to provide a report of relevant information.

Take the following data:

######################### Data ###################################
###################### DO NOT CHANGE #############################
peopleDf <- data.frame(PersonalID=c("ZP1U3EPU2FKAWI6K5US5LDV50KRI1LN7", "IA26X38HOTOIBHYIRV8CKR5RDS8KNGHV", "LASDU89NRABVJWW779W4JGGAN90IQ5B2"), 
           FirstName=c("Timmy", "Fela", "Sarah"),
           LastName=c("Tesa", "Falla", "Kerrigan"),
           DOB=c("2010-01-01", "1999-1-1", "1992-04-01"))
##################################################################
##################################################################

If you run the above in R you should get a dataframe called peopleDf which looks like this:

PersonalID FirstName LastName DOB
ZP1U3EPU2FKAWI6K5US5LDV50KRI1LN7 Timmy Tesa 2010-01-01
IA26X38HOTOIBHYIRV8CKR5RDS8KNGHV Fela Falla 1999-1-1
LASDU89NRABVJWW779W4JGGAN90IQ5B2 Sarah Kerrigan 1992-04-01

It’s a simple table. But let’s say we wanted to get a list of everyone born before 2000-01-01. Of course, we can easily see Timmy is the only person born after 2000. But if our table was thousands of records it wouldn’t be possible to quickly assess.

Luckily, this is pretty straight forward in SQL-R. We will use a less than operator (<). You probably remember this sign from high-school while solving inequalities. However, we will be using it as what’s known as a relational operator.

In short, it states,

Is x less than y

If x is less than y the computer is going to say the statement is true (or 1 in binary). If it is not, then the computer will say it’s false (or 0 in binary). Believe it or not, this simple operation is why you have a device in your pocket which could calculate the internal mass of the sun.

For us, things are a little simpler. We just want to know who was born before 2000. Let’s re-write the statement above with our problem:

Is Sarah’s DOB less than 2000-01-01

Well, what is Sarah’s DOB? 1992-04-01. Let’s rewrite and assess (gah, this feels like high-school algebra again).

Is 1992-04-01 less than 2000-01-01

Hmm. This can get confusing for humans, but more importantly, confusing to computers.

In English, we’d probably state this as,

Did 1992-04-01 come before 2001-01-01?

Essentially, that’s what we are doing. Just know, the computer will translate all dates into a number. This number is how many seconds transpired since 1970-01-01.

Why? On Thursday, January 1st 1970 the Universal Coordinated Time (UTC) was established. Think of it is when the world came together to standardize time. Computer people figured, “Well, if we have to convert dates into a raw number for computers to understand it, it might as well be the number of seconds since UTC was established.”

Ok, enough history lesson. How is this relevant?

  1. Computers convert dates into seconds since 1970-01-01.
  2. Comparing dates is actually comparing numbers.

Taking our statement again, let’s re-write it with the number of seconds since 1970-01-01

Is number of seconds between 1970-01-01 and 1992-04-01 less than number of seconds between 1970-01-01 and 2000-01-01

Which becomes:

Is 702,086,400 less than 46,684,800 seconds

Aha, now this makes sense. And the result is true. We can now say, in computer speak: Sarah was born before 2000-01-01.

Why? Really, dude.

In my world there is a saying: RFTM.

It’s hard to follow now days. Everything moves quick and we don’t have time to dig into the “Why.” But, like most things, if you want to be good, you must take the time to do so.

The reason we review how computers understand dates is it directly impacts how we write reports. Do you remember the date conversion trick to get dates to work in SQL from R? This is because R holds dates as the number of seconds since 1970 and passes it as a string to SQL. But, then SQL tries to convert the date from a date into seconds again, screwing everything up.

It pays to RFTM.

Filtering Dataframes by Date

Back to the problem. How do we write a script which provides a dataframe of people born before 2000-01-01?

The code is actually pretty simple,

library(sqldf)
nonMillennialsDf <- sqldf("SELECT * FROM peopleDf WHERE DOB < '2000-01-01'")

This should provide a nonMillennialsDf dataframe, which contains:

PersonalID FirstName LastName DOB
IA26X38HOTOIBHYIRV8CKR5RDS8KNGHV Fela Falla 1999-1-1
LASDU89NRABVJWW779W4JGGAN90IQ5B2 Sarah Kerrigan 1992-04-01

And there we go, for all my nerdsplaining the code’s pretty simple, right?

Well, there are a few gotchas. Notice the date we’ve written. It has the following format YYYY-MM-DD and is surrounded by single quotes. Any time you use dates in SQL they must be written in this format.

Another tricky part is trying to find if a date falls between two dates. Let’s take the peopleDf and write a query which provides everyone who was born between 1998-01-01 and 2005-01-01

Here’s the query.

bornBetweenDf <- sqldf("SELECT * FROM peopleDf WHERE DOB > '1998-01-01' AND DOB < '2005-01-01'") 

This should result in a table with only Fela:

PersonalID FirstName LastName DOB
IA26X38HOTOIBHYIRV8CKR5RDS8KNGHV Fela Falla 1999-1-1

It is important to understand, the first comparison removed Sarah, as 1992-04-01 is less than 1998-01-01. Then, the second comparison got rid of Timmy as 2010-01-01 is greater than 2005-01-01.

Now()

There is one more critical command in writing robust date comparisons. The NOW() function. This function is different in R and SQL, but pretty much every programming language has a version of the function.

Essentially, the NOW() asks the computer what today’s date is when the script runs.

In SQL-R it looks like this:

nowDf <- sqldf("SELECT *, DATE('NOW') As 'TodaysDate' FROM peopleDf")

This should provide:

PersonalID FirstName LastName DOB TodaysDate
ZP1U3EPU2FKAWI6K5US5LDV50KRI1LN7 Timmy Tesa 2010-14-01 2017-07-18
IA26X38HOTOIBHYIRV8CKR5RDS8KNGHV Fela Falla 1999-1-1 2017-07-18
LASDU89NRABVJWW779W4JGGAN90IQ5B2 Sarah Kerrigan 1992-04-01 2017-07-18

And it doesn’t matter when this script is run, it will always insert today’s date in the TodaysDate column. Nifty, right? Trust me, if you don’t see the possibilities yet, give it time. It’ll grow into one of your favorite functions.

Well, we can’t talk about the NOW() function without discussing the DATE() function I slipped in there. What does it do?

As we discussed earlier, the computer looks at dates as the number of seconds since 1970-01-01. When you use the NOW() function by itself then it will return the number of seconds–um, not something humans like to read. The DATE() function says, “Take whatever is inside the parentheses and try to convert it into a human readable date.” Voila! A human readable date.

Age

Let’s get fancy. We can use the NOW() function and our peopleDf to calculate everyone’s age.

peopleWithAgeDf <- sqldf("SELECT *, (DATE('NOW') - DOB) As 'Age' FROM peopleDf")

This should provide:

PersonalID FirstName LastName DOB Age
ZP1U3EPU2FKAWI6K5US5LDV50KRI1LN7 Timmy Tesa 2010-14-01 7
IA26X38HOTOIBHYIRV8CKR5RDS8KNGHV Fela Falla 1999-1-1 18
LASDU89NRABVJWW779W4JGGAN90IQ5B2 Sarah Kerrigan 1992-04-01 25

Cool, right? Now, it does not matter when this above code of line is run, it will calculate everyone’s age correctly.

One important note, if the date and time are wrong on your computer this calculation will be incorrect.

The nerd-judo which can be done with dates in SQL-R is endless. But this covers a lot of the basics.

If you’ve missed the code bits throughout this article, here it is all at once:

######################### Data ###################################
###################### DO NOT CHANGE #############################
peopleDf <- data.frame(PersonalID=c("ZP1U3EPU2FKAWI6K5US5LDV50KRI1LN7", "IA26X38HOTOIBHYIRV8CKR5RDS8KNGHV", "LASDU89NRABVJWW779W4JGGAN90IQ5B2"), 
           FirstName=c("Timmy", "Fela", "Sarah"),
           LastName=c("Tesa", "Falla", "Kerrigan"),
           DOB=c("2010-14-01", "1999-1-1", "1992-04-01"))
##################################################################
##################################################################
library(sqldf)
nonMillennialsDf <- sqldf("SELECT * FROM peopleDf WHERE DOB < '2000-01-01'")
bornBetweenDf <- sqldf("SELECT * FROM peopleDf WHERE DOB > '1998-01-01' AND DOB < '2005-01-01'") 
nowDf <- sqldf("SELECT *, DATE('NOW') As 'TodaysDate' FROM peopleDf")
peopleWithAgeDf <- sqldf("SELECT *, (DATE('NOW') - DOB) As 'Age' FROM peopleDf")