## ----include = FALSE----------------------------------------------------------
knitr::opts_chunk$set(
  collapse = TRUE,
  comment = "#>",
  eval = onnxr::onnx_is_loaded()
)

## ----download-----------------------------------------------------------------
model_url = "https://github.com/ultralytics/assets/releases/download/v8.4.0/yolo26n.onnx"
model_path = file.path(tempdir(), "yolo26n.onnx")
download.file(model_url, model_path, mode = "wb")

## ----session------------------------------------------------------------------
library(onnxr)

model = onnx_model(model_path)
print(model)

## -----------------------------------------------------------------------------
types = c(
    "person", "bicycle", "car", "motorcycle", "airplane", "bus", "train", 
    "truck", "boat", "traffic light", "fire hydrant", "stop sign", 
    "parking meter", "bench", "bird", "cat", "dog", "horse", "sheep", "cow", 
    "elephant", "bear", "zebra", "giraffe", "backpack", "umbrella", "handbag", 
    "tie", "suitcase", "frisbee", "skis", "snowboard", "sports ball", "kite", 
    "baseball bat", "baseball glove", "skateboard", "surfboard", "tennis racket", 
    "bottle", "wine glass", "cup", "fork", "knife", "spoon", "bowl", "banana", 
    "apple", "sandwich", "orange", "broccoli", "carrot", "hot dog", "pizza", 
    "donut", "cake", "chair", "couch", "potted plant", "bed", "dining table", 
    "toilet", "tv", "laptop", "mouse", "remote", "keyboard", "cell phone", 
    "microwave", "oven", "toaster", "sink", "refrigerator", "book", "clock", 
    "vase", "scissors", "teddy bear", "hair drier", "toothbrush"
)

## ----load---------------------------------------------------------------------
# load image from URL and center in 640x640 array
img_url = "https://uploads0.wikiart.org/images/johannes-vermeer/the-milkmaid.jpg!Large.jpg"
img = array(1, dim = model$input_shapes$images)
con = url(img_url, "rb")
raw = jpeg::readJPEG(readBin(con, "raw", n = 5e4))
close(con)
img[1, 1:3, 21:620, 53:587] = aperm(raw, c(3, 1, 2))

# helper to plot image
plot.image <- function(x) {
    old_par = par(mar = c(0, 0, 0, 0))
    x = aperm(x[1,,,], c(2, 3, 1))
    plot(0:1, 0:1, type = "n", axes = FALSE, asp = nrow(x) / ncol(x))
    rasterImage(x, 0, 0, 1, 1)
    par(old_par)
}
plot.image(img)

## ----run----------------------------------------------------------------------
res = onnx_run(model, img, simplify = TRUE)
dim(res)
head(res[1, ,])

## ----plot---------------------------------------------------------------------
plot.image(img)
idx_conf = which(res[1, , 5] >= 0.2) # minimum 20% confidence
for (j in idx_conf) {
    # map bounding box to plot coordinates
    x1 = res[1, j, 1] / 640
    y1 = 1 - res[1, j, 2] / 640
    x2 = res[1, j, 3] / 640
    y2 = 1 - res[1, j, 4] / 640
    # plot boxes and labels
    bg = "#f0f0ff"
    pad = 0.005
    rect(x1, y1, x2, y2, border = bg, lwd = 1)
    lbl = paste0(types[res[1, j, 6] + 1], " (", round(res[1, j, 5] * 100), "%)")
    sw = strwidth(lbl, cex = 0.8, font = 2)
    sh = strheight(lbl, cex = 0.8, font = 2)
    rect(x1, y1, x1 + sw + 2*pad, y1 + sh + 2*pad, col = paste0(bg, "a0"), border = bg)
    text(x1 + pad, y1 + pad, lbl, adj = c(0, -0.05), cex = 0.8, col = "#000", font = 2)
}