Before creating a neural network using the Sequential API, let's load the keras library into our environment and generate some dummy data:

library(keras)

Now, let's simulate some dummy data for this exercise:

x_data <- matrix(rnorm(1000*784), nrow = 1000, ncol = 784)
y_data <- matrix(rnorm(1000), nrow = 1000, ncol = 1)

We can check the dimension of the x and y data by executing the following commands:

dim(x_data)
dim(y_data)

The dimension of the x_data data is 1,000×784, whereas the dimension of the y_data data is 1,000×1.