在R中汇总数据帧或其他对象

Question

我希望这应该是一个简单的问题.我有几个数据框加载到工作区,标记为df01到df100,而不是所有代表的数字.我想在所有数据集中绘制特定列,例如在方框图中.如何使用globbing引用以df开头的所有对象,即:

boxplot(df00$col1, df02$col1, df04$col1)

 = 

boxplot(df*$col1)

Answer 1

idomatic方法是使用列表,或使用单独的环境.

您可以使用ls和创建此列表pattern

df.names <- ls(pattern = '^df')
# note 
# ls(pattern ='^df[[:digit:]]{2,}')
# may be safer if there are objects starting with df you don't want

df.list <- mget(df.names)
# note if you are using a version of R prior to R 3.0.0
# you will need `envir = parent.frame()`
# mget(ls(pattern = 'df'), envir = parent.frame()) 

# use `lapply` to extract the relevant columns

df.col1 <- lapply(df.list, '[[', 'col1')

# call boxplot   

boxplot(df.col1)