小洁老师布置作业之终极练习题

1.使用循环，对iris的1到4列分别画点图（plot）

library(ggplot2)
par(mfrow = c(2,2))
for (i in 1:4){
  plot(iris[,i], col = iris[,5])
}

2.生成一个随机数（rnorm）组成的10行6列的矩阵，列名为sample1，sample2….sample6，行名为gene1，gene2…gene10，分组为sample1、2、3属于A组，sample4、5、6属于B组。用循环对每个基因画ggplot2箱线图，并尝试拼图。

gene_matrix1 = matrix(rnorm(10*6), nrow = 10); gene_matrix1
gene_matrix1 <- data.frame(paste0("gene",1:10), gene_matrix1); gene_matrix1
colnames(gene_matrix1) <- c("gene.id", paste0("samples",1:6)); gene_matrix1
library(tidyr)
gene_matrix1_long <- gather(data=gene_matrix1, 
                             key = "sample_nm",
                             value = "gene_expression",
                             -gene.id,
                             factor_key = TRUE)
head(gene_matrix1_long)
gene_matrix1_long$group = ''; head(gene_matrix1_long)
gene_matrix1_long$group[1:(3*10)] = "A"; head(gene_matrix1_long)
gene_matrix1_long$group[(3*10+1):(6*10)] = "B"; tail(gene_matrix1_long)
tmp <- gene_matrix1_long[gene_matrix1_long$gene.id == "gene1",]; tmp
ggplot(data=tmp, mapping = aes(x = group, y = gene_expression, color = group) ) + 
  geom_boxplot()
multi_plot <- list()
for (i in 1:10){
  tmp <- gene_matrix1_long[gene_matrix1_long$gene.id == paste0("gene",i),]
  multi_plot[[i]] <- ggplot(data=tmp, mapping = aes(x = group, y = gene_expression, color = group) ) + 
    geom_boxplot()
}
library(gridExtra)
do.call('grid.arrange',c(multi_plot, ncol = 5))

3. 模拟出几个类似的文件，用R实现批量重命名