Analytics
Automated Data Visualizations in Python
Creating data visualizations in Python can be a challenge. For some it an be easy, but for most (and particularly new people to the language) they always have to search for the commands in the documentation or using some search engine. Over the past few years we have seem more and more libraries coming available to assist with many of the routine and tedious steps in most data science and machine learning projects. I’ve written previously about some data profiling libraries in Python. These are good up to a point, but additional work/code is needed to explore the data to suit your needs. One of these Python libraries, designed to make your initial work on a new data set easier is called AutoViz. It’s good to see there is continued development work on this library, which can be really help for creating initial sets of charts for all the variables in your data set, plus it has some additional features which help to make it very useful and cuts down on some of the additional code you might need to write.
The outputs from AutoViz are very extensive, and are just too long to show in this post. The images below will give you an indication of what if typically generated. I’d encourage you to install the library and run it on one of your data sets to see the full extent of what it can do. For this post, I’ll concentrate on some of the commands/parameters/settings to get the most out of AutoViz.
Firstly there is the install via pip command or install using Anaconda.
pip3 install autovizFor comparison purposes I’m going to use the same data set as I’ve used in the data profiling post (see above). Here’s a quick snippet from that post to load the data and perform the data profiling (see post for output)
import pandas as pd
import pandas_profiling as pp
#load the data into a pandas dataframe
df = pd.read_csv("/Users/brendan.tierney/Downloads/Video_Games_Sales_as_at_22_Dec_2016.csv")We can not skip to using AutoViz. It supports the loading and analzying of data sets direct from a file or from a pandas dataframe. In the following example I’m going to use the dataframe (df) created above.
from autoviz import AutoViz_Class
AV = AutoViz_Class()
df2 = AV.AutoViz(filename="", dfte=df) #for a file, fill in the filename and remove dfte parameterThis will analyze the data and create lots and lots of charts for you. Some are should in the following image. One the helpful features is the ‘data cleaning improvements’ section where it has performed a data quality assessment and makes some suggestions to improve the data, maybe as part of the data preparation/cleaning step.
There is also an option for creating different types of out put with perhaps the Bokeh charts being particularly useful.
chart_format='bokeh': interactive Bokeh dashboards are plotted in Jupyter Notebooks.chart_format='server', dashboards will pop up for each kind of chart on your web browser.chart_format='html', interactive Bokeh charts will be silently saved as Dynamic HTML files underAutoViz_Plotsdirectory
df2 = AV.AutoViz(filename="", dfte=df, chart_format='bokeh')
The next example allows for the report and charts to be focused on a particular dependent or target variable, particular in scenarios where classification will be used.
df2 = AV.AutoViz(filename="", dfte=df, depVar="Platform")
A little warning when using this library. It can take a little bit of time for it to run and create all the different charts. On the flip side, it save you from having to write lots and lots of code!
Migrating SAS files to CSV and database
Many organizations have been using SAS Software to analyse their data for many decades. As with most technologies organisations will move to alternative technologies are some point. Recently I’ve experienced this kind of move. In doing so any data stored in one format for the older technology needed to be moved or migrated to the newer technology. SAS Software can process data in a variety of format, one of which is their own internal formats. Thankfully Pandas in Python as a function to read such SAS files into a pandas dataframe, from which it can be saved into some alternative format such as CSV. The following code illustrates this conversion, where it will migrate all the SAS files in a particular directory, converts them to CSV and saves the new file in a destination directory. It also copies any existing CSV files to the new destination, while ignore any other files. The following code is helpful for batch processing of files.
import os
import pandas as pd
#define the Source and Destination directories
source_dir='/Users/brendan.tierney/Dropbox/4-Datasets/SAS_Data_Sets'
dest_dir=source_dir+'/csv'
#What file extensions to read and convert
file_ext='.sas7bdat'
#Create output directory if it does not already exist
if not os.path.exists(dest_dir):
os.mkdir(dest_dir)
else: #If directory exists, delete all files
for filename in os.listdir(source_dir):
os.remove(filename)
#Process each file
for filename in os.listdir(source_dir):
#Process the SAS file
if filename.endswith(file_ext):
print('.processing file :',filename)
print('...converting file to csv')
df=pd.read_sas(os.path.join(source_dir, filename))
df.to_csv(os.path.join(dest_dir, filename))
print('.....finished creating CSV file')
elif filename.endswith('csv'):
#Copy any CSV files to the Destination Directory
print('.copying CSV file')
cmd_copy='cp '+os.path.join(source_dir, filename)+' '+os.path.join(dest_dir, filename)
os.system(cmd_copy)
print('.....finished copying CSV file')
else:
#Ignore any other type of files
print('.ignoring file :',filename)
print('--Finished--')That’s it. All the files have now been converted and located in the destination directory.
For most, the above might be all you need, but sometimes you’ll need to move the the newer technology. In most cases the newer technology will easily use the CSV files. But in some instance your final destination might be a database. In my scenarios I use the CSV2DB app developed by Gerald Venzi. You can download the code from GitHub. You can use this to load CSV files into Oracle, MySQL, PostgreSQL, SQL Server and Db2 databases. Here’s and example of the command line to load into an Oracle Database.
csv2db load -f /Users/brendan.tierney/Dropbox/4-Datasets/SAS_Data_Sets/csv -t pva97nk -u analytics -p analytics -d PDB1
CAO Points 2022 – Grade inflation, deflation or in-line
Last week I wrote a blog post analysing the Leaving Cert results over the past 3-8 years. Part of that post also looked at the claim from the Dept of Education saying the results in 2022 would be “in-line on aggregate” with the results from 2021. The outcome of the analysis was grade deflation was very evident in many subjects, but when analysed and profiled at a very high level, they did look similar.
I didn’t go into how that might impact on the CAO (Central Applications Office) Points. If there was deflation in some of the core and most popular subjects, then you might conclude there could be some changes in the profile of CAO Points being awarded, and that in turn would have a small change on the CAO Points needed for a lot of University courses. But not all of them, as we saw last week, the increased number of students who get grades in the H4-H7 range. This could mean a small decrease in points for courses in the 520+ range, and a small increase in points needed in the 300-500-ish range.
The CAO have published the number of students of each 10 point range. I’ve compared the 2022 data, with each year going back to 2015. The following table is a high level summary of the results in 50 point ranges.
An initial look at these numbers and percentages might look like points are similar to last year and even 2020. But for 2015-2019 the similarity is closer. Again looking back at the previous blog post, we can see the results profiles for 20215-2019 are broadly similar and does indicate some normalisation might have been happening each year. The following chart illustrate the percentage of students who achieved points in each range.
From the above we can see the profile is similar across 2015-2019, although there does seem to be a flattening of the curve between 2015-2016!
Let’s now have a look at 2019 (the last pre-coivd year), 2021 and 2022. This will allow use to compare the “inflated” years to the last “normal” year.
This chart clearly shows a shifting of the profile to the left for the red line which represents 2022. This also supports my blog post last week, and that the Dept of Education has started the process of deflating marks.
Based on this shifting/deflating of marks, we could see the grade/CAO Points profiles reverting back to almost 2019 profile by 2025. For students sitting the Leaving Cert in 2023, there will be another shift to the left, and with another similar shift in 2024. In 2024, the students will be the last group to sit the Leaving Cert who were badly affected during the Covid years. Many of them lost large chunks on school and many didn’t sit the Junior Cert. I’d predict 2025 will see the first time the marks/points profiles will match pre-covid years.
For this analysis I’ve used a variety of tools including Excel, Python and Oracle Analytics.
The Dataset used can be found under Dataset menu, and listed as ‘CAO Points Profiles 2015-2022’. Also, check out the Leaving Certificate 2015-2022 dataset.
Leaving Cert 2022 Results – Inflation, deflation or in-line!
The Leaving Certificate 2022 results are out. Up and down the country there are people who are delighted with their results, while others are disappointed, and lots of other emotions.
The Leaving Certificate is the terminal examination for secondary education in Ireland, with most students being examined in seven subjects, with their best six grades counting towards their “points”, which in turn determines what university course they might get. Check out this link for learn more about the Leaving Certificate.
The Dept of Education has been saying, for several months, this results this year (2022) will be “in-line on aggregate” with the results from 2021. There has been some concerns about grade inflation in 2021 and the impact it will have on the students in 2022 and future years. At some point the Dept of Education needs to address this grade inflation and look to revert back to the normal profile of grades pre-Covid.
Let’s have a look to see if this is true, and if it is true when we look a little deeper. Do the aggregate results hide grade deflation in some subjects.
For the analysis presented in this blog post, I’ve just looked at results at Higher Level across all subjects, and for the deeper dive I’ll look at some of the most popular subjects.
Firstly let’s have a quick look at the distribution of grades by subject for 2022 and 2021.
Remember the Dept of Education said the 2022 results should be in-line with the results of 2021. This required them to apply some adjustments, after marking the exam scripts, to give an updated profile. The following chart shows this comparison between the two years. On initial inspection we can see it is broadly similar. This is good, right? It kind of is and at a high level things look broadly in-line and maybe we can believe the Dept of Education. Looking a little closer we can see a small decrease in the H2-H4 range, and a slight increase in the H5-H8.
Let’s dive a little deeper. When we look at the grade profile of students in 2021 and 2022, How many subjects increased the number of students at each grade vs How many subjects decreased grades vs How many approximately stated the same. The table below shows the results and only counts a change if it is greater than 1% (to allow for minor variations between years).
This table in very interesting in that more subjects decreased their H1s, with some variation for the H2-H4s, while for the lower range of H5-H7 we can see there has been an increase in grades. If I increased the margin to 3% we get a slightly different results, but only minor changes.
“in-line on aggregate” might be holding true, although it appears a slight increase on the numbers getting the lower grades. This might indicate either more of an adjustment to weaker students and/or a bit of a down shifting of grades from the H2-H4 range. But at the higher end, more subjects reduced than increase. The overall (aggregate) numbers are potentially masking movements in grade profiles.
Let’s now have a look at some of the core subjects of English, Irish and Mathematics.
For English, it looks like they fitted to the curve perfectly! keeping grades in-line between the two years. Mathematics is a little different with a slight increase in grades. But when you look at Irish we can see there was definite grade deflation. For each of these subjects, the chart on the left contains four years of data including 2019 when the last “normal” leaving certificate occurred. With Irish the grade profile has been adjusted (deflated) significantly and is closer to 2019 profile than it is to 2021. There was been lots and lots of discussions nationally about how and when grades will revert to normal profile. The 2022 profile for Irish seems to show this has started to happen in this subject, which raises the question if this is occurring in any other subjects, and is hidden/masked by the “in-line on aggregate” figures.
This blog post would become just too long if I was to present the results profile for each of the 42+ subjects.
Let’s have a look as two of the most common foreign languages, French and Spanish.
Again we can see some grade deflation, although not to be same extent as Irish. For both French and Spanish, we have reduced numbers for the H2-H4 range and a slight increase for H5-H7, and shift to the left in the profile. A slight exception is for those getting a H1 for both subjects. The adjustment in the results profile is more pronounced for French, and could indicate some deflation adjustments.
Next we’ll look at some of the science subjects of Physics, Chemistry and Biology.
These three subjects also indicate some adjusts back towards the pre-Covid profile, with exception of H1 grades. We can see the 2022 profile almost reflect the 2019 profile (excluding H1s) and for Biology appears to be at a half way point between 2019 and 2022 (excluding H1s)
Just one more example of grade deflation, and this with Design, Communication and Graphics (or DCG)
Yes there is obvious grade deflation and almost back to 2019 profile, with the exception of H1s again.
I’ve mentioned some possible grade deflation in various subjects, but there are also subjects where the profile very closely matches the 2021 profile. We have seen above English is one of those. Others include Technology, Art and Computer Science.
I’ve analyzed many more subjects and similar shifting of the profile is evident in those. Has the Dept of Education and State Examinations Commission taken steps to start deflating grades from the highs of 2021? I’d said the answer lies in the data, and the data I’ve looked at shows they have started the deflation process. This might take another couple of years to work out of the system and we will be back to “normal” pre-covid profiles. Which raises another interesting question, Was the grade profile for subjects, pre-covid, fitted to the curve? For the core set of subjects and for many of the more popular subjects, the data seems to indicate this. Maybe the “normal” distribution of marks is down to the “normal” distribution of abilities of the student population each year, or have grades been normalised in some way each year, for years, even decades?
For this analysis I’ve used a variety of tools including Excel, Python and Oracle Analytics.
The Dataset used can be found under Dataset menu, and listed as ‘Leaving Certificate 2015-2022’. An additional Dataset, I’ll be adding soon, will be for CAO Points Profiles 2015-2022.
Oralytics 
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