Question

I have to create a BufferedImage from a list of float array. With one float array i create one pixel width of the image. The total width is 500 px. The float array list’s size can be up to 10000 float array.

The image I built is some sort of history, so it is display in a time length graph. For example if the history is 6min the graph goes from 3 to -3 on the x axes, and the image should be centered against a middle point between 3 and -3.
The title says “interpolate”, but I’m not sure if the solution involves interpolation.

1. How can I choose float array from the list if the list size is over 500?
2. How can I split the list if its size is less than 500?

Answer 1

1 & 2) You have to calculate 500 pixels / size. That’s how many pixels you use for each value. If you have more than 500 float values, each value will take less than a pixel width. If you have less than 500 values, each value will take more than a pixel width.

Let’s say you have 700 float values. Each value will take 5/7 of a pixel. You can’t plot partial pixels, but you can sum and round to determine which value to plot.

• Value 1 – 5/7 – round to 1 – plot on the first pixel
• Value 2 – 10/7 – round to 1 – plot on the first pixel (overlay value 1)
• Value 3 – 15/7 – round to 2 – plot on the second pixel
• Value 4 – 20/7 – round to 3 – plot on the third pixel

and so on, until you’ve plotted all the values.

Let’s say you have 300 float values. Each value will take 5/3 of a pixel, or almost 2 pixels. Again, you sum and round to determine which values to plot.

• Value 1 – 5/3 – round to 2 – plot on the first and second pixels
• Value 2 – 10/3 – round to 3 – plot on the third pixel
• Value 3 – 15/3 – round to 5 – plot on the fourth and fifth pixels
• Value 4 – 20/3 – round to 7 – plot on the sixth and seventh pixels

and so on, until you’ve plotted all the values.