首先，我们需要知道，热图的原理就是根据你的matrix或者data.frame中行列数字大小，映射到一个个独立的小矩形面中的一种对数据直观演示的一种方法，只是用颜色深浅对数据大小对大面积数据展开后的展示；类似于条形图-直方图-饼图-boxplot，都是对数据的直观表示。

获得热图有很多的包，就用这个R自带的pheatmap包来就可以了，也是很漂亮的呀呀呀呀呀呀。

下面是 pheatmap（)的解释

例子可以用下面的代码表示

library(pheatmap)

  # Create test matrix

test = matrix(rnorm(200), 20, 10)

test[1:10, seq(1, 10, 2)] = test[1:10, seq(1, 10, 2)] + 3

test[11:20, seq(2, 10, 2)] = test[11:20, seq(2, 10, 2)] + 2

test[15:20, seq(2, 10, 2)] = test[15:20, seq(2, 10, 2)] + 4

colnames(test) = paste("Test", 1:10, sep = "")

rownames(test) = paste("Gene", 1:20, sep = "")

class(test)

str(test)

# Draw heatmaps

pheatmap(test)

pheatmap(test, kmeans_k = 2)

pheatmap(test, scale = "row", clustering_distance_rows = "correlation")

pheatmap(test,scale = "row")

pheatmap(test,scale="column")

pheatmap(test, color = colorRampPalette(c("navy", "white", "firebrick3"))(50))

###break 调节lengend的区间；col调节颜色；scale调节

bk = unique(c(seq(-8,8, length=100)))

pheatmap(test,breaks = bk,,scale="column")

pheatmap(test,breaks=unique(seq(-2,8,length=100)),color=colorRampPalette(c("navy", "white", "firebrick3"))(100))

pheatmap(test, cluster_row = FALSE)

pheatmap(test, legend = FALSE)

# Show text within cells

pheatmap(test, display_numbers = TRUE)

pheatmap(test, display_numbers = TRUE, number_format = "\%.1e")

pheatmap(test, display_numbers = matrix(ifelse(test > 5, "*", ""), nrow(test)))

pheatmap(test, cluster_row = FALSE, legend_breaks = -1:4, legend_labels = c("0",

                                                                            "1e-4", "1e-3", "1e-2", "1e-1", "1"))

# Fix cell sizes and save to file with correct size

pheatmap(test, cellwidth = 15, cellheight = 12, main = "Example heatmap")

pheatmap(test, cellwidth = 15, cellheight = 12, fontsize = 8, filename = "test.pdf")

# Generate annotations for rows and columns

annotation_col = data.frame(

  CellType = factor(rep(c("CT1", "CT2"), 5)),

  Time = 1:5

)

rownames(annotation_col) = paste("Test", 1:10, sep = "")

annotation_row = data.frame(

  GeneClass = factor(rep(c("Path1", "Path2", "Path3"), c(10, 4, 6)))

)

rownames(annotation_row) = paste("Gene", 1:20, sep = "")

# Display row and color annotations

pheatmap(test, annotation_col = annotation_col)

pheatmap(test, annotation_col = annotation_col, annotation_legend = FALSE,legend_breaks = NA)

pheatmap(test, annotation_col = annotation_col, annotation_row = annotation_row)

pheatmap(test, annotation_col = annotation_col, annotation_row = annotation_row,annotation_legend  = F)

# Specify colors

ann_colors = list(

  Time = c("white", "firebrick"),

  CellType = c(CT1 = "#1B9E77", CT2 = "#D95F02"),

  GeneClass = c(Path1 = "#7570B3", Path2 = "#E7298A", Path3 = "#66A61E")

)

pheatmap(test, annotation_col = annotation_col, annotation_colors = ann_colors, main = "Title")

pheatmap(test, annotation_col = annotation_col, annotation_row = annotation_row,

        annotation_colors = ann_colors)

pheatmap(test, annotation_col = annotation_col, annotation_colors = ann_colors[2])

# Gaps in heatmaps

pheatmap(test, annotation_col = annotation_col, cluster_rows = FALSE, gaps_row = c(10, 14))

pheatmap(test, annotation_col = annotation_col, cluster_rows = FALSE, gaps_row = c(10, 14),

        cutree_col = 2)

# Show custom strings as row/col names

labels_row = c("", "", "", "", "", "", "", "", "", "", "", "", "", "", "",

              "", "", "Il10", "Il15", "Il1b")

table(labels_row)

pheatmap(test, annotation_col = annotation_col, labels_row = labels_row)

# Specifying clustering from distance matrix

drows = dist(test, method = "minkowski")

dcols = dist(t(test), method = "minkowski")

pheatmap(test, clustering_distance_rows = drows, clustering_distance_cols = dcols)

# Modify ordering of the clusters using clustering callback option

callback = function(hc, mat){

  sv = svd(t(mat))$v[,1]

  dend = reorder(as.dendrogram(hc), wts = sv)

  as.hclust(dend)

}

pheatmap(test, clustering_callback = callback)

## Not run:

# Same using dendsort package

library(dendsort)

callback = function(hc, ...){dendsort(hc)}

pheatmap(test, clustering_callback = callback)

完整例子：###例子

###创建matrix

test = matrix(rnorm(200), 20, 10)

test[1:10, seq(1, 10, 2)] = test[1:10, seq(1, 10, 2)] + 3

test[11:20, seq(2, 10, 2)] = test[11:20, seq(2, 10, 2)] + 2

test[15:20, seq(2, 10, 2)] = test[15:20, seq(2, 10, 2)] + 4

colnames(test) = paste("Test", 1:10, sep = "")

rownames(test) = paste("Gene", 1:20, sep = "")

###建立annotation数据框

annotation_col = data.frame(

  CellType = factor(rep(c("CT1", "CT2"), 5)),

  Time = 1:5

)

rownames(annotation_col) = paste("Test", 1:10, sep = "")

annotation_row = data.frame(

  GeneClass = factor(rep(c("Path1", "Path2", "Path3"), c(10, 4, 6)))

)

rownames(annotation_row) = paste("Gene", 1:20, sep = "")

class(test)

str(test)

pheatmap(test,scale = "row",clustering_distance_rows = "euclidean",clustering_distance_cols = "euclidean", clustering_method = "complete",

        cluster_rows = TRUE,cluster_cols = TRUE,cutree_rows = NA, cutree_cols = NA,

        color = colorRampPalette(c("navy", "white", "firebrick3"))(100),

        border_color = "grey60",cellwidth = NA, cellheight = NA,

        legend = TRUE, legend_breaks = NA,legend_labels = NA, breaks = unique(c(seq(-6,6, length=100))),

        annotation_row = annotation_row , annotation_col = annotation_col,annotation = NA, annotation_colors = NA, annotation_legend = TRUE,

        annotation_names_row = TRUE, annotation_names_col = TRUE,

        show_rownames = T, show_colnames = T, main = "Heatmap",

        display_numbers = F, number_format = "%.2f", number_color = "grey30")