在用R语言编程中，界面上出现了“+”号，是什么意思？如何删除错误的输入，如何清屏？谢谢

2023-04-14 18:06:01Python020

在用R语言编程中，界面上出现了“+”号，是什么意思？如何删除错误的输入，如何清屏？谢谢,第1张

“+”标示语句没有闭合，比如在循环中，在分支中，或者写函数等，分多行都会有加号；

直接键盘按Esc键退出就可以把+号去掉，恢复正常的编辑状态。清屏用快捷键Ctrl+L 就可以清除所有编辑的语句。

例如；

td<-function(fx,a,b,r){ #(fx:是表达式，方程是fx=0,变量是dux；a，b，区间[a,b],r是精度。

x<-ada<-eval(fx)

调用函数：

fx<-expression(x*x-x-1)

a<-1b<-2r<-1e-5

td(fx,a,b,r)

扩展资料：

R语言有程序的控制结构和函数function。尽管R语言是解释型语言，但是可以用编译的方式实现，调用方法是source(file.R)命令。R语言的软件包能在编程环境中，通过子菜单下载后安装，因此是无障碍的。

程序中加载软件包的命令，

>library(parallel) #并行计算软件包，单线程多核

查找软件包中所有函数，

>library(help=parallel)

>help(packet=parallel)

R语言和解释型语言一样，没有变量声明。R语言能编写c++程序，应用Rcpp软件包。

参考资料来源：百度百科-R语言编程

用R作图，比用EXCEL要灵活的多。散点图，直接用plot()即可多类别，在R中就是多变量，用pionts() 加类别拟合曲线用 fit<- lm()lines(fit)添加文字用 text()

可以使用数据标号“text()”函数text()函数跟在画图函数语句后面，即先画出图，再标号。

下面为来自R的text()函数使用方法（疑难词汇已经标出）

Description

text draws the strings given in the vector(矢量) labels at the coordinates(坐标) given by x and y. y may be missing since xy.coords(x, y) is used for construction of the coordinates.

Usage

text(x, ...)

## Default S3 method:

text(x, y = NULL, labels = seq_along(x$x), adj = NULL,pos = NULL, offset = 0.5, vfont =NULL,cex = 1, col = NULL, font = NULL, ...)

Arguments

x, y

numeric(数) vectors(矢量) of coordinates(坐标) where the text labels should be written. If the length of x and y differs, the shorter one is recycled.

labels

a character vector or expression specifying the text to be written. An attempt is made to coerce(强制) other language objects (names and calls) to expressions, and vectors and other classed objects to character vectors byas.character. If labels is longer than x and y, the coordinates(坐标) are recycled to the length of labels.

adj

one or two values in [0, 1] which specify(指定) the x (and optionally(可选择的) y) adjustment(调整) of the labels(标签). On most devices(装置) values outside that interval will also work.

pos

a position specifier for the text. If specified this overrides(代理佣金) any adj value given. Values of 1, 2, 3 and 4, respectively(分别地) indicate(表明) positions below, to the left of, above and to the right of the specified coordinates.

offset

when pos is specified(指定), this value gives the offset(抵消) of the label(标签) from the specified coordinate(坐标) in fractions(分数) of a character width.

vfont

NULL for the current font family, or a character vector(矢量) of length 2 for Hershey vector fonts. The first element(元素) of the vector selects a typeface and the second element selects a style. Ignored(驳回诉讼) if labels is an expression.

cex

numeric character expansion factor(因素)multiplied by par("cex") yields(产量) the final character size. NULL and NA are equivalent to 1.0.

col, font

the color and (if vfont = NULL) font to be used, possibly vectors(矢量). These default to the values of the global graphical parameters in par().

...

further graphical parameters (from par), such as srt, family and xpd.

Details

labels must be of type character or expression (or be coercible(可强迫的) to such a type). In the latter case, quite a bit of mathematical(数学的) notation(符号) is available such as sub- and superscripts(上标), greek letters,fractions(分数), etc.

adj allows adjustment of the text with respect to (x, y). Values of 0, 0.5, and 1 specify(指定) left/bottom, middle and right/top alignment(队列), respectively(分别地). The default is for centered text, i.e., adj = c(0.5, NA).Accurate(精确的) vertical(垂直的) centering needs character metric(度量标准) information on individual(个人的) characters which is only available on some devices(装置). Vertical alignment is done slightly differently for character strings and for expressions: adj = c(0,0) means to left-justify and to align(结盟) on the baseline for strings but on the bottom of the bounding box for expressions. This also affects vertical(垂直的) centering: for strings the centeringexcludes(排除) any descenders(下降) whereas(然而) for expressions it includes them. Using NA for strings centers them, including descenders.

The pos and offset arguments can be used in conjunction(结合) with values returned by identify to recreate(再创造) an interactively(交互式地) labelled(贴上标签的) plot(情节).

Text can be rotated(旋转的) by using graphical parameters srt (see par)this rotates about the centre set by adj.

Graphical parameters col, cex and font can be vectors(矢量) and will then be applied cyclically(周期的) to the labels (and extra values will be ignored(驳回诉讼)). NA values of font are replaced by par("font"), and similarly for col.

Labels whose x, y or labels value is NA are omitted(省略) from the plot(情节).

What happens when font = 5 (the symbol(象征) font) is selected can be both device- and locale-dependent. Most often labels will be interpreted(说明) in the Adobe symbol encoding, so e.g. "d" is delta, and "\300" is aleph.

Euro symbol

The Euro symbol may not be available in older fonts. In current versions of Adobe symbol fonts it is character 160, so text(x, y, "\xA0", font = 5) may work. People using Western European locales(场所) on Unix-alikes can probably select ISO-8895-15 (Latin-9) which has the Euro as character 165: this can also be used for postscript and pdf. It is \u20ac in Unicode, which can be used in UTF-8 locales(场所).

In all the European Windows encodings the Euro is symbol(象征) 128 and \u20ac will work in all locales: however not all fonts will include it. It is not in the symbol font used for windows and related devices(装置), including the Windows printer.

References

Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth &Brooks/Cole.

Murrell, P. (2005) R Graphics. Chapman(叫卖小贩) &Hall/CRC Press.