在R中迭代生成名称以存储图 [英] Generating names iteratively in R for storing plots

问题描述

我正在使用R遍历数据帧，执行计算并绘制图.

I'm using R to loop through a data frame, perform a calculation and to make a plot.

for(i in 2 : 15){
# get data
dataframe[,i]  

# do analysis

# make plot
a <- plot()
}

有没有一种方法可以使用"i"的值来创建绘图对象名称"a"?例如，+"i"<-plot().然后，我想将其添加到矢量中，以便获得一系列绘图，以便以后在要生成pdf时可以使用.也许还有另一种存储方式.

Is there a way that I can make the plot object name 'a', using the value of 'i'? For example, a + "i" <- plot(). Then I want to add that to a vector so I have a series of plots that I can then use at a later stage when I want to make a pdf. Or perhaps there is another way of storing this.

我熟悉paste()函数，但是我还没有弄清楚如何使用它来定义对象.

I'm familiar with the paste() function but I haven't figured out how to define an object using it.

推荐答案

如果您想要绘图对象的向量"，最简单的方法可能是将它们存储在list中.使用paste()为您的绘图创建一个名称，然后将其添加到列表中:

If you want a "vector" of plot objects, the easiest way is probably to store them in a list. Use paste() to create a name for your plot and then add it to the list:

# Create a list to hold the plot objects.
pltList <- list()

for( i in 2:15 ){

  # Get data, perform analysis, ect.

  # Create plot name.
  pltName <- paste( 'a', i, sep = '' )

  # Store a plot in the list using the name as an index.
  # Note that the plotting function used must return an *object*.
  # Functions from the `graphics` package, such as `plot`, do not return objects.
  pltList[[ pltName ]] <- some_plotting_function()

}

如果您不想将绘图存储在列表中，并且从字面上想创建一个名称包含在pltName中的新对象，则可以使用assign():

If you didn't want to store the plots in a list and literally wanted to create a new object that had the name contained in pltName, then you could use assign():

# Use assign to create a new object in the Global Environment
# that gets it's name from the value of pltName and it's contents
# from the results of plot()
assign( pltName, plot(), envir = .GlobalEnv )

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