将字符串转换为数字

问题描述

我导入了一个测试文件并尝试制作直方图

I've imported a test file and tried to make a histogram

pichman <- read.csv(file="picman.txt", header=TRUE, sep="/t")
hist <- as.numeric(pichman$WS)

但是，我从数据集中的值中得到了不同的数字.本来以为是因为有文字，所以删了文字:

However, I get different numbers from values in my dataset. Originally I thought that this because I had text, so I deleted the text:

table(pichman$WS)
ws <- pichman$WS[pichman$WS!="Down" & pichman$WS!="NoData"]

但是，我的数字仍然很高，有人知道吗?

However, I am still getting very high numbers does anyone have an idea?

推荐答案

我怀疑您对因子有问题.例如，

I suspect you are having a problem with factors. For example,

> x = factor(4:8)
> x
[1] 4 5 6 7 8
Levels: 4 5 6 7 8
> as.numeric(x)
[1] 1 2 3 4 5
> as.numeric(as.character(x))
[1] 4 5 6 7 8

一些评论:

• 您提到您的向量包含字符Down"和NoData".期望/希望 as.numeric 对这些值做什么?
• 在 read.csv 中，尝试使用参数 stringsAsFactors=FALSE
• 你确定是 sep="/t 而不是 sep="\t"
• 使用命令head(pitchman)检查数据的前几行
• 此外，当您不提供数据时，很难猜测您的问题是什么.最小的工作示例总是可取的.例如，我不能运行命令 pichman <- read.csv(file="picman.txt", header=TRUE, sep="/t") 因为我没有访问数据集.

• You mention that your vector contains the characters "Down" and "NoData". What do expect/want as.numeric to do with these values?
• In read.csv, try using the argument stringsAsFactors=FALSE
• Are you sure it's sep="/t and not sep="\t"
• Use the command head(pitchman) to check the first fews rows of your data
• Also, it's very tricky to guess what your problem is when you don't provide data. A minimal working example is always preferable. For example, I can't run the command pichman <- read.csv(file="picman.txt", header=TRUE, sep="/t") since I don't have access to the data set.

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