如何创建返回给定数据框直方图的 function？

Question

I need to create a function called histagram, the function receives 3 arguments: data frame, column name, and color number.

if all the arguments meet the criteria (valid data frame, color number an integer, and column name input must be character and the column must be of type numeric, the function returns a plot of histogram of the chosen column with the chosen color.

Also we need to change the "x - axis" so it will represent the column name input.

my script:

histagram = function(dataframe, columnName, colorNumber) {
    if (!is.data.frame(dataframe)){
    print("Please enter a Data frame structure")
  } else if(!is.integer(as.integer(colorNumber))){
    print("Enter a char columne name")    
  } else if(!is.character(columnName)){
    print("Color must be a integer")  
  } else {
    return(hist(dataframe$as.numeric(columnName), xlab = "columnName", col = as.integer(colorNumber)))
  }
} 

I tested the function to see if it worked:

histagram(dataframe = airdf, colorNumber = 7, columnName = "Temp")

I used the airquality data frame, which is a built-in data frame in R. airdf = airquality.

I'm getting an error message -

Error in dataframe$as.numeric(columnName) : attempt to apply non-function
Called from: hist(dataframe$as.numeric(columnName), xlab = "columnName", col = as.integer(colorNumber))

What needs to be changed in my code for it to work?

Many thanks!

Answer 1

In addition to Martin Gal's comment, you should also remove the quotations around columnName under the xlab argument and consider adding something to the histogram title. If you don't specify the histogram title, it just says "Histogram of as.numeric(dataframe[, columnName])", which is a bit clunky.

data(airquality)
airdf <- airquality

histagram <- function(dataframe, columnName, colorNumber) {
  if (!is.data.frame(dataframe)){
    print("Please enter a Data frame structure")
  } else if(!is.integer(as.integer(colorNumber))){
    print("Enter a char columne name")    
  } else if(!is.character(columnName)){
    print("Color must be a integer")  
  } else {
    return(hist(as.numeric(dataframe[, columnName]), # <- from Martin Gal
                main = paste("Histogram of", columnName), # <- dynamic title 
                xlab = columnName, # <- remove quotes here
                col = as.integer(colorNumber)))
  }
} 

histagram(dataframe = airdf, colorNumber = 7, columnName = "Temp")