r的heatmap.2中图例的大小

在`heatmap.2`中，可以使用`keysize`参数来设置color key的大小。具体来说，`keysize`参数是一个数值向量，表示color key的相对大小，其默认值为1。如果要将color key的大小增加一倍，可以将`keysize`设置为2；如果要将color key的大小减小一半，可以将`keysize`设置为0.5。

以下是一个示例代码：

library(gplots)

# 生成一个矩阵作为示例数据
set.seed(123)
mat <- matrix(rnorm(60), nrow = 6)

# 设置color key的外观和大小
key.par <- list(mar = c(5, 0, 0, 0), side = "right", length = 1.5, width = 0.2, cex.axis = 0.8,
                col = heat.colors(10), col.axis = "black", labels = NULL, at = NULL, tick = TRUE,
                tick.col = "black", key.xlab = NULL, key.ylab = NULL, reverse = FALSE)
keysize <- 2

# 绘制heatmap
heatmap.2(mat, trace = "none", dendrogram = "none", Rowv = FALSE, Colv = FALSE, key = TRUE,
          key.title = "My Title", key.title.position = "top", key.title.cex = 1.2, key.par = key.par,
          margins = c(5, 5), labCol = "", labRow = "", main = "My Heatmap", cex.main = 1.5,
          col = colorRampPalette(c("blue", "white", "red"))(100), breaks = seq(-2, 2, length.out = 101),
          dendWidth = 0, symm = TRUE, density.info = "none", tracecol = "black", add.expr = NULL,
          sepcolor = "white", sepwidth = 0.05, sep = c(0.5, 0.5), scale = "none", na.color = "gray",
          na.rm = TRUE, cellnote = mat, notecol = "black", notecex = 0.8, keysize = keysize)

在这个示例中，`keysize`参数用来设置color key的大小。最终的图形如下所示：