Error in eval(expr, envir, enclos) : could not find function "eval"

Question

I am working on the Kaggle Digit Recognizer problem.when I tried the given code I got the error.

Error in eval(expr, envir, enclos) : could not find function "eval"

library(ggplot2)
library(proto)
library(readr)
train <- data.frame(read_csv("../input/train.csv"))

labels   <- train[,1]
features <- train[,-1]

rowsToPlot <- sample(1:nrow(train), 49)

rowToMatrix <- function(row) {
   intensity <- as.numeric(row)/max(as.numeric(row))
   return(t(matrix((rgb(intensity, intensity, intensity)), 28, 28)))
}

geom_digit <- function (digits, labels) GeomRasterDigit$new(geom_params = 
list(digits=digits),stat = "identity", position = "identity", data = NULL, 
inherit.aes = TRUE)

I am getting the error when I run the following segment.

GeomRasterDigit <- proto(ggplot2:::GeomRaster, expr={
draw_groups <- function(., data, scales, coordinates, digits, ...) {
bounds <- coord_transform(coordinates, data.frame(x = c(-Inf, Inf), y = c(
- Inf, Inf)), scales)
x_rng <- range(bounds$x, na.rm = TRUE)
y_rng <- range(bounds$y, na.rm = TRUE)
rasterGrob(as.raster(rowToMatrix(digits[data$rows,])), x_rng[1], y_rng[1], 
diff(x_rng), diff(y_rng),default.units = "native", just =c("left","bottom"),
interpolate = FALSE)
}
})

Link for the complete code : https://www.kaggle.com/benhamner/digit-recognizer/example-handwritten-digits/code

Answer 1

Take a look at the latest ggplot2 code on github. ggproto now replaces proto among other changes.

The code below should work fine.

 GeomRasterDigit <- ggproto(ggplot2:::GeomRaster, expr={
 draw_groups <- function(., data, scales, coordinates, digits, ...) {
 bounds <- coord_transform(coordinates, data.frame(x = c(-Inf, Inf), y = c(
 - Inf, Inf)), scales)
 x_rng <- range(bounds$x, na.rm = TRUE) 
 y_rng <- range(bounds$y, na.rm = TRUE)
 rasterGrob(as.raster(rowToMatrix(digits[data$rows,])), x_rng[1], y_rng[1], 
 diff(x_rng), diff(y_rng),default.units = "native", just =c("left","bottom"),
 interpolate = FALSE)
 }
 })

There is a vignette about ggproto that is a good read.