Code on xie

Batch PDF Editing

Mon, 31 Jul 2023 21:54:52 +0700

I needed to do batch operations with images and get a merged PDF output. Desiring to minimize a number of tools, at the end I’ve done all processing with ImageMagick and Ghostscript. Zsh and GNU parallel were also my friends.

Convert and Chop 4 sides

convert input.png -crop +300+300 -crop -300-300 output.pdf

Convert and Rotate

convert input.png -rotate -90 -page A4 output.pdf

Convert many files in parallel

find . -name '*.jpg' | parallel convert {} {.}.pdf

Merge and optimize

gs -dBATCH -dNOPAUSE -q -sDEVICE=pdfwrite -dPDFSETTINGS=/ebook -sOutputFile=merged.pdf \
	one.pdf two.pdf three.pdf

Result file will be optimized because of -dPDFSETTINGS=/ebook.

Malaysian fuel prices and open data

Sat, 29 Jul 2023 00:19:39 +0700

I wanted to write a blog post about Malaysian fuel prices. RON95 petrol and diesel are subsidised by the government. Compare these graphs.

Diesel price per litre, in ringgits

RON95 petrol price per litre, in ringgits

RON97 petrol price per litre, in ringgits

These subsidies are also a reason why it’s illegal to fuel a car with RON95 if you’re a foreigner.

Did you like the graphs above?

This data and these graphs are provided by the OpenDOSM project. DOSM is Department of Statistics Malaysia. The website is a collection of DOSM’s data published by Creative Commons licenses. Frontend and Backend repositories are also published as Free Software!

And I like it. Researchers are funded by taxpayers. Taxpayers get their data freely.

Git Symbolic Links in Windows

Fri, 30 Jun 2023 02:34:18 +0800

Today I learned: git clone breaks symlinks on Windows system.

Thankfully, I used symlinks in my project by mistake and I could delete them. On internet there’re people who rely on a bunch of symlinks and search for hacks to workaround msysgit issue.

https://stackoverflow.com/questions/5917249/git-symbolic-links-in-windows/59761201