Figuring out Postgres Part 2(Adding data)

My database is set up. My table is set up. Now it's time to add some data. There are 2 main ways we can do it - add data from an external file, or add data with Python.

Adding data from an external file

A colleague of mine introduced me to a website - Kaggle. You can download datasets in a few different formats from this site which is pretty amazing! I found one for cat breed characteristics. I don't put much stock in breeds and that sort of thing, but I thought it would be a nice data set to use.

The table I created previously wasn't exactly a good match for this data so I created a new table. One that was specifically for domestic cats and not all cats, big and small.

In SQL Shell(psql)

Using the copy command in the screenshot below, I copied data from the csv file to my domestic_cats table.

Printing a simple query in my Python file revealed that the data was actually copied. It was pretty exciting to see it all there.

Data printed to the terminal

Input data with Python

Back in my Python file I inserted a new entry into the table and printed it to the terminal by querying that entry using it's primary key, BREED_NAME.

There are of course several different ways you can execute both options. You could insert data from a csv file into the database using code rather than shell commands. You could ask for user input instead of hardcoding data insertions into the table each time. But to me, those are essentially just variations of adding data from a file and adding data using code.

Comments

Deviants in a normal world

It's definitely been a bit since I've seen this graphy. Anyone who has learnt about standard deviation knows this graph. Standard Deviation Standard deviation shows us how spread out all the values in a set are from the mean. The higher the standard deviation, the more spread out the values are over a wider range and the flatter this curve. In a normal distribution, most values are within 1 standard deviation from the mean(the green part of the graph). Apparently NumPy can calculate standard deviation too! import numpy numSet = [ *lots of numbers* ] numSetStdDev = numpy.std(numSet) Variance The variance also indicates how spread out the values in a set are. It measures the average degree to which each value differs from the mean. variance = standard deviation ^2 import numpy numSet = [ *lots of numbers * ] numSetVar = numpy.var(numSet) Source: https://www.w3schools.com/python/python_ml_standard_deviation.asp

I gotta feeling...

I've been helping a colleague with his portfolio site. He's making it retro video game themed at my suggestion. He found an interesting pixelated font called arcade classic and used it for the headings on his page. Unfortunately, some of the letters almost overlapped, making it not quite readable. Before letter spacing I looked into typography ages ago and learnt about letter and word spacing and wondered if that was something that I could fiddle with using CSS. Turns out it is a property you can customise. I opened up Chrome Dev tools and added 3 pixels of letter spacing and it looked so much better. And there's letter spacing too, so that's pretty neat. After letter spacing Can't say CSS is my favourite thing ever but it's always nice to learn something new in unexpected ways.

Snakes and ladders

I've started on my Python course. So far, the code has been familiar because the first few basic codes are similar to Javascript. And then modules happened. Confusion and despair! What is the world is 'if __name__ == "__main__": ' and why must I reach this section of my course on a public holiday when none of the instructors are in :( Stack overflow to the rescue, providing me a lifeline while I was drowning in a pit of serpents. I feel eternally indebted to a particular Mr Fooz. Picture from here From my understanding, when the Python interpreter reads a source file, it first sets the variable __name__ and then it executes all the code in the file. If that particular file that you are running(i.e. your module) is the main program, the interpreter will assign '__name__ = "__main__" '. Thereafter, any code in the aforementioned 'if' statement is run. If you have, instead, imported a module, the interpreter assigns '__name__ ...

I do it for my cat

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