循环通过数据框和变量名 [英] Loop through data frame and variable names

问题描述

我正在寻找一种使用FOR循环自动化R中的一些图表的方法：

I am looking for a way to automate some diagrams in R using a FOR loop:

dflist <- c("dataframe1", "dataframe2", "dataframe3", "dataframe4")

for (i in dflist) {
  plot(i$var1, i$var2)
}

所有数据帧都有相同的变量，即var1，var2。

All dataframes have the same variables, i.e. var1, var2.

似乎 for 循环不是这里最优雅的解决方案，但我不明白如何使用

It seems for loops are not the most elegant solution here, but I don't understand how to use the apply functions for diagrams.

编辑：

我的原始示例使用 mean（）在原始问题中没有帮助，所以我将其更改为绘图函数。

My original example using mean() didn't help in the original question, so I changed it to a plot function.

推荐答案

为了进一步添加Beasterfield的答案，似乎你想对每个数据框架进行一些复杂的操作。

To further add to Beasterfield's answer, it seems like you want to do some number of complex operations on each of the data frames.

可以在apply语句中具有复杂的函数。所以你现在有：

It is possible to have complex functions within an apply statement. So where you now have:

for (i in dflist) {
  # Do some complex things
}

这可以翻译成：

lapply(dflist, function(df) {
  # Do some complex operations on each data frame, df
  # More steps

  # Make sure the last thing is NULL. The last statement within the function will be
  # returned to lapply, which will try to combine these as a list across all data frames.
  # You don't actually care about this, you just want to run the function.
  NULL
})

使用情节的一个更具体的例子：

A more concrete example using plot:

# Assuming we have a data frame with our points on the x, and y axes,
lapply(dflist, function(df) {
  x2 <- df$x^2
  log_y <- log(df$y)
  plot(x,y)
  NULL
})

您还可以编写多个参数的复杂函数：

You can also write complex functions which take multiple arguments:

lapply(dflist, function(df, arg1, arg2) {
  # Do something on each data.frame, df
  # arg1 == 1, arg2 == 2 (see next line)
}, 1, 2) # extra arguments are passed in here

希望这可以帮助你！

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