radarImage {robustbase} | R Documentation

## Satellite Radar Image Data from near Munich

### Description

The data were supplied by A. Frery. They are a part of a synthetic aperture satellite radar image corresponding to a suburb of Munich. Provided are coordinates and values corresponding to three frequency bands for each of 1573 pixels.

### Usage

    data(radarImage)

### Format

A data frame with 1573 observations on the following 5 variables.

`X.coord`

  a numeric vector

`Y.coord`

  a numeric vector

`Band.1`

  a numeric vector

`Band.2`

  a numeric vector

`Band.3`

  a numeric vector

### Source

The website accompanying the MMY-book: http://www.wiley.com/legacy/wileychi/robust_statistics

### Examples

    data(radarImage)
    plot(Y.coord ~ X.coord, data = radarImage)

    ## The 8 "clear" outliers (see also below)
    ii8 <- c(1548:1549, 1553:1554, 1565:1566, 1570:1571)
    outF <- 1+(seq_len(nrow(radarImage)) %in% ii8)
    pairs(radarImage[, 3:5], main = "radarImage (n = 1573)",
          col = outF, pch=outF)

    ## Finding outliers -----------------------------------------

    set.seed(1)
    system.time(cc.ri <- covMcd(radarImage))# ~ 0.1 sec
    ## check for covMcd() consistency:
    iiO <- as.integer(
     c(262, 450:451, 480:481, 509, 535, 542, 597, 643, 669, 697, 803:804, 832:834,
       862:864, 892, 989, 1123, 1145, 1223:1224, 1232:1233, 1249:1250, 1267, 1303,
       1347, 1357, 1375, 1411, 1419:1420, 1443, 1453, 1504, 1510:1512,
       1518:1521, 1525:1526, 1543:1544, 1546:1555, 1557:1558, 1561:1562, 1564:1566,
       1569:1571, 1573))
    length(iiO) # 73 -- other seeds sometimes give 72, rarely 71 "outliers"
    isO <- cc.ri$mcd.wt == 0
    stopifnot(identical(iiO, which(isO)),
              identical(ii8, which(cc.ri$mah > 100)),
              length(intersect(cc.ri$best, iiO)) == 0)

    cc <- c(adjustcolor("black", 0.4), adjustcolor("tomato", 0.8))
    pairs(radarImage, main = "radarImage (n = 1573) + Outliers", gap=0,
          col = cc[1+isO], pch = c(1,8)[1+isO], cex = 0.8)

[Package robustbase version 0.92-8 Index]