如何从R中的.csv文件中读取列向量

Question

So I have data being processed in Python that I'm outputting as a .csv file. I would like R to be able to read the .csv file in such a way that it turns it into a dataframe in which some of the columns are actually vectors.

Is this even possible and how would I format a .csv so that this could happen? Thanks!

Answer 1

First, vectors are simply a sequence of data elements. And data frames are lists of equal length vectors.

Hence, you can easily reference each column of a data frame as a vector.

df <- read.csv('C:\\Path\\To\\DataFile.csv')

v1 <- df[[1]]  # by column number
v2 <- df[["col1"]]  # by column name
v3 <- df$col1  # by column name

Answer 2

You can just read the csv in r and it will be a dataframe by default:

data<-read.csv("nameOfCSVFile.csv", header=T)

You can then slice the dataframe by column and obtain that column as a vector using the $ operator: data$header1 returns the first column of the dataframe as a vector.

Just make sure that your .csv file is in the order you want ie

header1,header2,etc.
     1,2,etc.
     4,5, etc.
     etc..

Answer 3

Actually, a dataframe is a collection of vectors. If you want to have the data in form of a vector, you simple have to use the subsetting functions:

df <- data.frame(matrix(rnorm(10), nrow=5))

 df$X1
## [1]  1.05376208  0.05020266  1.79204302 -1.73712344 -1.29208706
 is.vector(df$X1)
## [1] TRUE

So by subsetting, here you get a vector of the data frame column X1 .