clarifying IF in processing: to compare values in a IF conditional you use == instead of only =. one equal sign denotes that something has a specific value, while == denotes a comparison (if x equals 0 is written if(x == 0){statements}, then. summarizing, when declaring a variable you use x = 0; while when comparing with a if conditional you use if(x == 0), for example.

in this particular conditional if by dividing j by (1+int(random(randnudge))) the rest equals 0 [j % (1+int(random(randnudge))) == 0] the statements inside the brackets are read.

this particular statement modify the Y position of the ellipse on the screen based on a randomly defined comparison (in this case the int(random(randnudge)) which returns a value from 0 to 8 and converts it to int with the int() function to be divided by j and then if it returns no rest the if statements run). if the result returns true height_of_peaks becomes (-height_of_peaks) {if height_of peaks was 1 it becomes -1 and if height_of_peaks was -1 it becomes 1}, incrementing rowhop in the opposite direction as before (rowhop is related to height_of_peaks because inside the for (int j = 1 ; j < steps et cetera) iteration it is stated that rowhop -= height_of_peaks; this way each time this for iteration runs the rowhop value increases or decreases by 1 depending on the result of the if(j%1 + int(...) et cetera) conditional.

rowhop is called on the ellipse() function together with the value of i to define what is the Y position of each ellipse. while the value of i defines in which row the ellipse must be drawn, the rowhop make each ellipse on the same line occupy a slightly different Y pos.