Using getValues in R but unable to obtain corresponding row number and column number

Question

I currently have a list of PC values for each row and column of a raster. I would like an output that looks like this:

x     y     PC
1    500    -3.45
1    501    -2.8

Here, x and y stand for row number and column number.

I am using the current code in R, but I end up obtaining a matrix only.

r <- pre_pca$map$PC1
r
class       : RasterLayer 
dimensions  : 339, 246, 83394  (nrow, ncol, ncell)
resolution  : 0.04166667, 0.04166667  (x, y)
extent      : 72.45833, 82.70833, 8.083333, 22.20833  (xmin, xmax, ymin, ymax)
coord. ref. : +proj=longlat +ellps=WGS84 +towgs84=0,0,0,0,0,0,0 +no_defs 
data source : in memory
names       : PC1 
values      : -9.283828, 3.889567  (min, max)

s <- getValues(r, format="matrix")
head(s)


  X1       X2       X3       X4       X5       X6       X7       X8       X9      X10      X11
 1 NA       NA       NA 3.121756 3.056287 3.030809       NA 2.977990 2.954814 2.869022 2.802258
 2 NA       NA 3.154253 3.116532 3.023211 2.984813 2.973805 2.917697 2.896259 2.795462 2.754197
 3 NA       NA 3.079315 3.038321 2.985467 2.923184 2.909316 2.853848 2.858537 2.767026 2.749681
 4 NA       NA 3.083964 2.983488 2.948048 2.915955 2.879146 2.859355 2.748576 2.760476 2.724777

I have shown only the first 4 rows and x number of columns, but I would not want an output like this. In addition, please help removing NAs as well.

Answer 1

Looks like I found the answer in the reshape package in R

library(reshape2)
s <- melt(s)

> str(s)
'data.frame':   83394 obs. of  3 variables:
 $ X1   : int  1 2 3 4 5 6 7 8 9 10 ...
 $ X2   : int  1 1 1 1 1 1 1 1 1 1 ...
 $ value: num  NA NA NA NA NA NA NA NA NA NA ...

Using complete.cases in the base package in R, I kept only those rows that did not have any NAs.

s <- s[complete.cases(s),]
>str(s)

'data.frame':   54207 obs. of  3 variables:
 $ X1   : int  5 6 7 8 2 3 4 5 6 7 ...
 $ X2   : int  2 2 2 2 3 3 3 3 3 3 ...
 $ value: num  3.05 2.98 2.91 2.89 3.15 ...