CSV file to Histogram in R
I'm also an R newbie, and I ran into the same thing. I made two separate mistakes, actually, so I'll describe them both here.
Mistake 1: Passing a frequency table to hist(). Originally I was trying to pass a frequency table to hist()
instead of passing in the raw data. One way to fix this is to use the rep()
("replicate") function to explode your frequency table back into a raw dataset, as described here:
- Creating a histogram using aggregated data
- Simple R (histogram) from counted csv file
Instead of that, though, I just decided to read in my original dataset instead of the frequency table.
Mistake 2: Wrong data type. My raw data CSV file contains two columns: hostname
and bookings
(idea is to count the number of bookings each host generated during some given time period). I read it into a table.
> tbl <- read.csv('bookingsdata.csv')
Then when I tried to generate a histogram off the second column, I did this:
> hist(tbl[2])
This gave me the "'x' must be numeric" error you mention in a comment. (It was trying to read the "bookings" column header in as a data value.)
This fixed it:
> hist(tbl$bookings)
You should really start to read some basic R manual... CRAN offers a lot of them (look into the Manuals and Contributed sections)
In any case:
setwd("path/to/csv/file")
myvalues <- read.csv("filename.csv")
hist(myvalues, 100) # Example: 100 breaks, but you can specify them at will
See the manual pages for those functions for more help (accessible through ?read.table
, ?read.csv
and ?hist
).
To plot the histogram, the values must be of numeric class i.e the data must be of numeric value. Here the value of x seems to be of some other class.
Run the following command and see:
sapply(myvalues[1,],class)