Reading working day price data into time-series format

[price.csv](https://github.com/facebook/prophet/files/6385127/price.csv)

> library(prophet)
> df <- read.csv('price.csv', sep = ' ')
> str(df)
'data.frame': 1579 obs. of 2 variables:
$ data : chr "2015-01-02" "2015-01-05" "2015-01-06" "2015-01-07" ...
$ price: num 674 660 630 572 587 ...
> m <- prophet(df)
Error in fit.prophet(m, df, ...) :
Dataframe must have columns 'ds' and 'y' with the dates and values respectively.

I can't find why this doesn't work...-_-;
This data file contains working day price of a commodity.

I also want to know a simple way to read this data into a time-series, but,, as this data doesn't have weekend and holiday price s.. it makes me astray.