调用函数生成值，但不绘制图形。

Question

我有一个函数，在这个函数中可以生成一个地图和一个coef_val值。但是我想知道是否有办法调用同一函数，只得到生成的值，而不绘制图形？我知道存在一种可能性，就是创建一个新函数，例如f2，去掉绘图部分，但我不想这样做。还有其他方法吗？

library(dplyr)
library(tidyverse)
library(lubridate)


Test <- structure(
  list(date1= c("2021-06-28","2021-06-28"),
       date2 = c("2021-07-01","2021-07-01"),
       Category = c("FDE","ABC"),
       Week= c("Friday","Monday"),
       DR1 = c(14,11),
       DR01 = c(14,12), DR02= c(14,12),DR03= c(19,15),
       DR04 = c(15,14),DR05 = c(15,14),
       DR06 = c(12,14)),
  class = "data.frame", row.names = c(NA, -2L))


f1 <- function(df1, dmda, CategoryChosse) {
  
  x<-df1 %>% select(starts_with("DR0"))
  
  x<-cbind(df1, setNames(df1$DR1 - x, paste0(names(x), "_PV")))
  PV<-select(x, date2,Week, Category, DR1, ends_with("PV"))
  
  med<-PV %>%
    group_by(Category,Week) %>%
    summarize(across(ends_with("PV"), median),.groups = 'drop')
  
  SPV<-df1%>%
    inner_join(med, by = c('Category', 'Week')) %>%
    mutate(across(matches("^DR0\\d+$"), ~.x + 
                    get(paste0(cur_column(), '_PV')),
                  .names = '{col}_{col}_PV')) %>%
    select(date1:Category, DR01_DR01_PV:last_col())
  
  SPV<-data.frame(SPV)
  
  mat1 <- df1 %>%
    filter(date2 == dmda, Category == CategoryChosse) %>%
    select(starts_with("DR0")) %>%
    pivot_longer(cols = everything()) %>%
    arrange(desc(row_number())) %>%
    mutate(cs = cumsum(value)) %>%
    filter(cs == 0) %>%
    pull(name)
  
  (dropnames <- paste0(mat1,"_",mat1, "_PV"))
  
  datas<-SPV %>%
    filter(date2 == ymd(dmda)) %>%
    group_by(Category) %>%
    summarize(across(starts_with("DR0"), sum),.groups = 'drop') %>%
    pivot_longer(cols= -Category, names_pattern = "DR0(.+)", values_to = "val") %>%
    mutate(name = readr::parse_number(name))
  colnames(datas)[-1]<-c("Days","Numbers")
  
  if(as.Date(dmda) < min(as.Date(df1$date1))){
    datas <- datas %>% 
      group_by(Category) %>% 
      slice(1:max(Days)+1) %>%
      ungroup
  }else{
    datas <- datas %>% 
      group_by(Category) %>% 
      slice((as.Date(dmda) - min(as.Date(df1$date1) [
        df1$Category == first(Category)])):max(Days)+1) %>%
      ungroup
  }
  
  plot(Numbers ~ Days,  xlim= c(0,45), ylim= c(0,30),
       xaxs='i',data = datas,main = paste0(dmda, "-", CategoryChosse))
  
  model <- nls(Numbers ~ b1*Days^2+b2,start = list(b1 = 0,b2 = 0),data = datas, algorithm = "port")
  
  new.data <- data.frame(Days = with(datas, seq(min(Days),max(Days),len = 45)))
  new.data <- rbind(0, new.data)
  lines(new.data$Days,predict(model,newdata = new.data),lwd=2)
  coef_val<-coef(model)[2]
  points(0, coef_val, col="red",pch=19,cex = 2,xpd=TRUE)
  return(coef_val)
}

f1(Test, "2021-07-01", "ABC")
b2 
12.5

- user16774617

---

是的 - f <- function(x, plot=TRUE) {if(plot) plot(x); return(x)} - thelatemail

我不明白在哪里插入这个。难道不需要选择一天的部分和类别吗？例如：f1(Test, "2021-07-01", "ABC") - user16774617

这只是一个示例，说明您可以返回一个值并选择是否需要图形。将所有的 plot、points 等代码放在 if(plot) {...} 中，然后在函数中添加一个 plot= 参数来选择是否需要绘制。 - thelatemail

具体来说，您需要在“plot”、“lines”和“points”周围包装条件语句。 - r2evans

谢谢您的回答！您能把它以答案的形式留下来，这样我就可以更好地测试它了吗？ - user16774617

Answer 1

您可以提供一个参数，让用户选择是否进行绘图，默认为 FALSE。然后只需使用 if 语句包装对 plot() 的调用，如果该参数为 TRUE 则执行。

library(dplyr)
library(tidyverse)
library(lubridate)


Test <- structure(
  list(date1= c("2021-06-28","2021-06-28"),
       date2 = c("2021-07-01","2021-07-01"),
       Category = c("FDE","ABC"),
       Week= c("Friday","Monday"),
       DR1 = c(14,11),
       DR01 = c(14,12), DR02= c(14,12),DR03= c(19,15),
       DR04 = c(15,14),DR05 = c(15,14),
       DR06 = c(12,14)),
  class = "data.frame", row.names = c(NA, -2L))


f1 <- function(df1, dmda, CategoryChosse, plot = FALSE) {
  
  x<-df1 %>% select(starts_with("DR0"))
  
  x<-cbind(df1, setNames(df1$DR1 - x, paste0(names(x), "_PV")))
  PV<-select(x, date2,Week, Category, DR1, ends_with("PV"))
  
  med<-PV %>%
    group_by(Category,Week) %>%
    summarize(across(ends_with("PV"), median),.groups = 'drop')
  
  SPV<-df1%>%
    inner_join(med, by = c('Category', 'Week')) %>%
    mutate(across(matches("^DR0\\d+$"), ~.x + 
                    get(paste0(cur_column(), '_PV')),
                  .names = '{col}_{col}_PV')) %>%
    select(date1:Category, DR01_DR01_PV:last_col())
  
  SPV<-data.frame(SPV)
  
  mat1 <- df1 %>%
    filter(date2 == dmda, Category == CategoryChosse) %>%
    select(starts_with("DR0")) %>%
    pivot_longer(cols = everything()) %>%
    arrange(desc(row_number())) %>%
    mutate(cs = cumsum(value)) %>%
    filter(cs == 0) %>%
    pull(name)
  
  (dropnames <- paste0(mat1,"_",mat1, "_PV"))
  
  datas<-SPV %>%
    filter(date2 == ymd(dmda)) %>%
    group_by(Category) %>%
    summarize(across(starts_with("DR0"), sum),.groups = 'drop') %>%
    pivot_longer(cols= -Category, names_pattern = "DR0(.+)", values_to = "val") %>%
    mutate(name = readr::parse_number(name))
  colnames(datas)[-1]<-c("Days","Numbers")
  
  if(as.Date(dmda) < min(as.Date(df1$date1))){
    datas <- datas %>% 
      group_by(Category) %>% 
      slice(1:max(Days)+1) %>%
      ungroup
  }else{
    datas <- datas %>% 
      group_by(Category) %>% 
      slice((as.Date(dmda) - min(as.Date(df1$date1) [
        df1$Category == first(Category)])):max(Days)+1) %>%
      ungroup
  }
  
  model <- nls(Numbers ~ b1*Days^2+b2,start = list(b1 = 0,b2 = 0),data = datas, algorithm = "port")
  coef_val<-coef(model)[2]

  if(plot){
    new.data <- data.frame(Days = with(datas, seq(min(Days),max(Days),len = 45)))
    new.data <- rbind(0, new.data)
    
    plot(Numbers ~ Days,  xlim= c(0,45), ylim= c(0,30),
           xaxs='i',data = datas,main = paste0(dmda, "-", CategoryChosse))
    lines(new.data$Days,predict(model,newdata = new.data),lwd=2)
    points(0, coef_val, col="red",pch=19,cex = 2,xpd=TRUE)
  }

  return(coef_val)
}

展示如何使用它：

f1(Test, "2021-07-01", "ABC")
f1(Test, "2021-07-01", "ABC", plot = TRUE)

- BHudson

---

抱歉回复晚了，感谢@BHudson的回复。当我执行f1(Test, "2021-07-01", "ABC")时，出现以下错误：Error in plot.xy(xy.coords(x, y), type = type, ...) : plot.new has not been called yet。 - user16774617

@JVieira；这是因为以下绘图命令lines(new.data$Days,predict(model,newdata = new.data),lwd=2)和points(0, coef_val, col="red",pch=19,cex = 2,xpd=TRUE)也需要包含在if(plot)语句中。因此，需要将if/plot语句移动到nls调用之后。 - user20650

感谢@user20650的回复。我按照您说的做了，它生成了图形和系数。但这不是我想要的，我只需要系数值。如果您可以的话，请给出您的答案。 - user16774617

@JVieira; 我更新了BHudson的回答，所以您不应该在这里遇到您提到的错误。(希望这样做没关系，BHudson——我只是稍微调整了一下以避免绘图错误) - user20650

现在，它可以运行了！感谢@user20650和@BHudson！=） - user16774617

Answer 2

您可以将图形重定向到一个NULL文件中。从help(pdf)中的相关部分：

file: 一个字符字符串，给出文件路径。[...] 如果它是'NULL'，则不会创建外部文件（实际上，不会进行任何绘制）[...]

因此，为了不生成任何绘图：

pdf(NULL)
f1(Test, "2021-07-01", "ABC")
dev.off()

- Karolis Koncevičius