Vector graphics are a series of instructions to the computer: put a line here and a circle there, etc. The alternative is raster graphics, like. bmp, which tells the computer that this pixel is blue and that pixel is red and so on. If you re-scale it (and of course, web browsers on other people’s computers do that all the time no matter what you tell them to do) then you get fuzz where it has to combine or interpolate pixels.Īdvantage two: you can read it, and edit it.
And now the corresponding iris-stata.svg file: Let’s open iris_stata.pdf in a text editor: PDF is a vector format (although it can have embedded rasters) but isn’t human-readable. This is the reason why open data activists get furious when PDFs are dumped on a webpage by a government agency claiming to have fulfilled its open data obligations. You can see immediately that SVG is plain text (which is to say, some kind of ASCII / UTF-8 / Unicode text that you can read and indeed edit), whereas PDF is squashed down to a binary format.
However, you can write those SVG instructions in many ways.Īlso, SVG can be trimmed back to the bare essentials, while PDFs are full of weird and wonderful things that are not relevant to your chart (like the ability to store bookmarks, highlight text or digitally sign forms). The nice example above came from Stata 14, but now let’s compare how different software writes out the same chart as SVG. We’ll get them all out and then delve into the SVG code.
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