小编d.b*_*d.b的帖子

人们常说,人们应该更喜欢lapply过for循环.有一些例外,例如Hadley Wickham在他的Advance R书中指出.

(http://adv-r.had.co.nz/Functionals.html)(修改到位,递归等).以下是这种情况之一.

仅仅为了学习,我试图以功能形式重写感知器算法,以便对相对性能进行基准测试.来源(https://rpubs.com/FaiHas/197581).

这是代码.

# prepare input
data(iris)
irissubdf <- iris[1:100, c(1, 3, 5)]
names(irissubdf) <- c("sepal", "petal", "species")
head(irissubdf)
irissubdf$y <- 1
irissubdf[irissubdf[, 3] == "setosa", 4] <- -1
x <- irissubdf[, c(1, 2)]
y <- irissubdf[, 4]

# perceptron function with for
perceptron <- function(x, y, eta, niter) {

  # initialize weight vector
  weight <- rep(0, dim(x)[2] + 1)
  errors <- rep(0, niter)


  # loop over number of …

使用有什么好处with()？在帮助文件中,它提到它在从数据创建的环境中评估表达式.这有什么好处？创建环境并在那里评估它是否更快,而不是仅仅在全球环境中评估它？或者还有其他我想念的东西？

背景:

我正在建立一个基于@ YihuiXie的R包的博客blogdown.

问题:

当我render_site(),所有源文件(*.Rmd)都被渲染 - 甚至重新重新保存未更改的源文件.

这种完全重新渲染是耗时且不必要的(我认为).

问题/期望的解决方案:

如何防止blogdown重新呈现未更改的源文件？我希望blogdown只渲染新的或更改的源文件.

我已经尝试过的:

• 我读过博客书 ; Yihui似乎提出了"重建所有"的方法.

• 我已经阅读了render_site()和的帮助文件hugo_build().第一个声明它将呈现所有rmd文件.相比之下hugo_build(),没有编织rmd文件(即,rmd文件未编译为md文件).

• 我已经检查了SO和谷歌,但这个问题似乎没有被问过.

SessionInfo():

R version 3.4.4 (2018-03-15)
Platform: x86_64-apple-darwin15.6.0 (64-bit)
Running under: macOS High Sierra 10.13.4

Matrix products: default
BLAS: /System/Library/Frameworks/Accelerate.framework/Versions/A/Frameworks/vecLib.framework/Versions/A/libBLAS.dylib
LAPACK: /Library/Frameworks/R.framework/Versions/3.4/Resources/lib/libRlapack.dylib

locale:
[1] en_US.UTF-8/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/en_US.UTF-8

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base     

other attached packages:
[1] shiny_1.1.0

loaded via a namespace (and …

有没有办法在R Markdown中自动使错误的文本颜色变红,而无需稍后手动编辑HTML.

---
title: ""
---

#### Example 1

```{r e1, error = TRUE}
2 + "A"
```

#### Example 2

```{r e2, error = TRUE}
2 + 2
```

在上面的代码中,输出Example 1必须是红色.目前,我编辑生成的HTML(添加style="color:red;"到适当的标签),但我想知道是否有自动方式.假设在编织之前不知道代码是否会产生错误.

我需要在ggplot中重现InDesign中生成的图，以实现可重现性。

在此特定示例中，我将两个图合并到一个合成图中（{patchwork}为此我使用了程序包）。

然后，我需要将连接一个图上关键点的线与底部图上的对应点重叠。

这两个图是从相同的数据生成的，具有相同的x轴值，但具有不同的y轴值。

我已经在Stack Overflow上看到了这些示例，但是这些示例处理的是跨构面的绘制线，在这里尝试跨单独的图绘制线时，这在这里不起作用：

• ggplot，跨构面绘制多条线
• ggplot，跨构面的点之间绘制线

我尝试了几种方法，到目前为止，我最接近的方法是：

1. 使用{grid}package 添加带有grobs的行
2. 使用将第二个图转换为gtable {gtable}，并将面板的剪辑设置为off，以便我可以将线向上延伸到该图的面板之外。
3. 再次将绘图合并为一张图像{patchwork}。

问题出在最后一步，因为x轴现在不再像添加线并将剪辑设置为off之前那样对齐（请参见代码示例）。

我也曾尝试用相结合的情节ggarrange，{cowplot}并{egg}与{patchwork}来自最接近的一次。

以下是我尝试创建的最佳最小reprex的尝试，但仍在捕捉我想要实现的细微差别。

library(ggplot2)
library(dplyr)
library(tidyr)
library(patchwork)
library(gtable)
library(grid)

# DATA
x <- 1:20
data <- data.frame(
  quantity = x,
  curve1 = 10 + 50*exp(-0.2 * x),
  curve2 = 5 + 50*exp(-0.5 * x),
  profit = c(seq(10, 100, by = 10),
             seq(120, -240, by = -40))
)

data_long <- data %>% …

所以我尝试了之前提出的问题答案.但我仍然有相同的错误消息:我正在尝试rJava在R中加载库

library(rJava) 

Error : .onLoad failed in loadNamespace() for 'rJava', details:   call: inDL(x, as.logical(local), as.logical(now), ...)   
error: unable to load shared object 'C:/Users/Lauriane/Documents/R/win-library/3.3/rJava/libs/x64/rJava.dll':   
LoadLibrary failure:  The specified module could not be found.  
Error: package or namespace load failed for ‘rJava’

请帮忙,

谢谢

我有一个矢量 x

x = c(1, 1, 2.00005, 1, 1, 0, 0, 0, 0, 1, 2, 0, 3, 4, 0, 0, 0, 0, 1, 2, 3, 1, 3)

我需要将由n(在这种情况下,假设n为 3)或更多零分隔的值拆分为不同的组.

期望的输出将是

list(x1 = c(1, 1, 2.00005, 1, 1),
     x2 = c(1, 2, 0, 3, 4),
     x3 = c(1, 2, 3, 1, 3))
#$x1
#[1] 1.00000 1.00000 2.00005 1.00000 1.00000

#$x2
#[1] 1 2 0 3 4

#$x3
#[1] 1 2 3 1 3

以下方法不起作用,因为x即使 …

我想为我的教室创建一个清单，列出每组4名学生的可能。如果我有20个学生，我该如何在R中按组创建该对象，其中我的行是每个组合，并且学生ID的完整列表有20列，第1-4列是“ group1”，第5-9列是“ group2”等。

下面列出了每组4个学生（x1，x2，x3和x4）的可能组合。现在，对于列出的每一行，其他4组4个学生的可能性是什么？因此，应该有20列（Group1_1：4，Group2_1：4，Group3_1：4，Group4_1：4，Group5_1：4）。

combn(c(1:20), m = 4)

期望的输出

Combination 1 = Group1[1, 2, 3, 4] Group2[5, 6, 7, 8], Group3[9, 10, 11, 12], etc. 
Combination 2 = Group1[1, 2, 3, 5]... etc. 

那里有很多关于组合的帖子，可能这已经被回答了，我只是找不到。任何帮助表示赞赏！

这是groupby对 a 的两个操作pandas.DataFrame：

import pandas


d = pandas.DataFrame({"a": [1, 2, 3, 4, 5, 6],
                      "b": [1, 2, 4, 3, -1, 5]})

grp1 = pandas.Series([1, 1, 1, 1, 1, 1])
ans1 = d.groupby(grp1).apply(lambda x: x.a * x.b.iloc[0])

grp2 = pandas.Series([1, 1, 1, 2, 2, 2])
ans2 = d.groupby(grp2).apply(lambda x: x.a * x.b.iloc[0])

print(ans1.reset_index(drop=True))
# a  0  1  2  3  4  5
# 0  1  2  3  4  5  6

print(ans2.reset_index(drop=True))
# 0     1
# 1     2
# …

如何为r中的变量分配一个非常长的字符串？

以下工作正常

testVar <- "test;test;"  

但是以下+在RStudio控制台中给出了一个奇怪的结果.

testVar <- "test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test;test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

当我按下Esc按钮并打印时testVar,它只打印test;test;