Quick and easy solutions

library(gplots)
library("RColorBrewer")
## scale the dataset
df = scale(mtcars)

knitr::kable(head(df, 5)) ## first five rows
mpg cyl disp hp drat wt qsec vs am gear carb
Mazda RX4 0.1508848 -0.1049878 -0.5706198 -0.5350928 0.5675137 -0.6103996 -0.7771651 -0.8680278 1.1899014 0.4235542 0.7352031
Mazda RX4 Wag 0.1508848 -0.1049878 -0.5706198 -0.5350928 0.5675137 -0.3497853 -0.4637808 -0.8680278 1.1899014 0.4235542 0.7352031
Datsun 710 0.4495434 -1.2248578 -0.9901821 -0.7830405 0.4739996 -0.9170046 0.4260068 1.1160357 1.1899014 0.4235542 -1.1221521
Hornet 4 Drive 0.2172534 -0.1049878 0.2200937 -0.5350928 -0.9661175 -0.0022995 0.8904872 1.1160357 -0.8141431 -0.9318192 -1.1221521
Hornet Sportabout -0.2307345 1.0148821 1.0430812 0.4129422 -0.8351978 0.2276543 -0.4637808 -0.8680278 -0.8141431 -0.9318192 -0.5030337
heatmap(df, scale = "none", 
        col= colorRampPalette(brewer.pal(10, "Blues"))(256))

## or eventually with color key

heatmap.2(df, scale = "none", col = greenred(100),
          trace = "none", density.info = "none")

## With another package
library("pheatmap") 
pheatmap(df, cutree_rows = 4, colorRampPalette(brewer.pal(10, "OrRd"))(256))

## An Interactive way
library("d3heatmap")
d3heatmap(scale(mtcars), colors = "Spectral",
          k_row = 4, # Number of groups in rows 
          k_col = 2) # Number of groups in columns 
library(dendextend)
# order for rows
Rowv <- mtcars %>% scale %>% dist %>% hclust %>% as.dendrogram %>%
  set("branches_k_color", k = 3) %>% set("branches_lwd", 1.2) %>%
  ladderize
# Order for columns: We must transpose the data
Colv <- mtcars %>% scale %>% t %>% dist %>% hclust %>% as.dendrogram %>% set("branches_k_color", k = 2, value = c("orange", "blue")) %>% set("branches_lwd", 1.2) %>%
  ladderize

heatmap(scale(mtcars), Rowv = Rowv, Colv = Colv, scale = "none")

## with gqplot package
heatmap.2(scale(mtcars), scale = "none", col = greenred(100),
          Rowv = Rowv, Colv = Colv,
          trace = "none", density.info = "none")

## with d3heatmap

d3heatmap(scale(mtcars), colors = "Spectral",
                               Rowv = Rowv, Colv = Colv)

Code suggestions come from Alboukadel Kassambara, Practical Guide To Cluster Analysis in R