Adding colnames to a dataframe

Question

When I read the csv it adds a X to my first element. I don't know what's wrong?

Also when I add colnames to a dataframe my first row disappears.

> grocery<-read.csv("groceries.csv")
> grocery
       spinach X2.00
1         rice   3.0
2 toilet paper   4.0
3        bread   2.4
4         milk   3.1
5        apple   0.4
> 
> class(grocery)
[1] "data.frame"
> colnames(grocery)<-c("item","price")
> grocery
          item price
1         rice   3.0
2 toilet paper   4.0
3        bread   2.4
4         milk   3.1
5        apple   0.4
>

Here's the raw csv:

spinach,2.00
rice,3.00
toilet paper,4.00
bread,2.40
milk,3.10
apple,0.40

BrodieG · Accepted Answer · 2014-03-06 21:49:21Z

3

try:

read.csv("groceries.csv", header=F)

by default that function assumes the first row of your data is a header, and uses it for colnames instead of as data. Since numbers are not valid colnames, it prepends X to the numbers to make it character. When you re-set colnames, you overwrite what used to be the first row of your data that was actually saved as colnames instead of as a row of data.

Setting header=F will prevent read.csv from using the first row as colnames.

answered Mar 6, 2014 at 21:49

BrodieG

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JPC · Accepted Answer · 2014-03-06 21:49:43Z

1

you're also losing your first row of data, spinach and 2.00. It's making those the column names, 2.00 becomes X2.00 to comply with R naming conventions of permissible names. Add column headers

answered Mar 6, 2014 at 21:49

JPC

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