xts format assign name for index column

Question

I have a xts file format which when reading didn't have a name for the index column, see below. How do I assign a name to it? Ideally, I wanted to use the date time field for plotting at subsequent stages. Thanks.

                    Elapsed Time Total Inflow Total Evap Surface Infil
2021-04-30 10:02:00        0.033            0      0.125             0
2021-04-30 10:04:00        0.067            0      0.125             0
2021-04-30 10:06:00        0.100            0      0.125             0
2021-04-30 10:08:00        0.133            0      0.125             0
2021-04-30 10:10:00        0.167            0      0.125             0
2021-04-30 10:12:00        0.200            0      0.125             0

score 0 · Answer 1 · answered Dec 24 '21 at 09:30

One suggestion would be to use plotting functions that can deal with xts data. There are not many functions that can do that.

Other option is to just make index as a separate column in the dataframe instead of an xts object.

library(xts)
data <- data.frame(index = index(sample.xts), coredata(sample.xts))
data

#         index     Open     High      Low    Close
#1   2007-01-02 50.03978 50.11778 49.95041 50.11778
#2   2007-01-03 50.23050 50.42188 50.23050 50.39767
#3   2007-01-04 50.42096 50.42096 50.26414 50.33236
#4   2007-01-05 50.37347 50.37347 50.22103 50.33459
#5   2007-01-06 50.24433 50.24433 50.11121 50.18112
#6   2007-01-07 50.13211 50.21561 49.99185 49.99185
#...
#...

data

data(sample_matrix)
sample.xts <- as.xts(sample_matrix, descr='my new xts object')

Thanks, I prefer to retain the format in xts as of now. Good to know it can be converted. — Aravindan Kalai, Dec 25 '21 at 22:35

G. Grothendieck · Accepted Answer · 2021-12-25T11:20:08.993

We assume that the question is asking how to plot an xts object such as x in the Note at the end.

There are numerous plotting functions for zoo and xts objects (every xts object is also a zoo object) so it is unnecessary to convert it to a data frame (although in the last example below we show this.) All the facilities of each of these plotting systems are available when using this. Also shown below is how to specify the x label in each case.

library(xts)  # this also pulls in zoo

# classic graphics
plot(as.zoo(x), xlab = "Time")

# lattice graphics
library(lattice)
xyplot(x, xlab = "Time")

## ggplot2 graphics
library(ggplot2)
autoplot(x) + xlab("Time")

# convert to data frame and then use matplot
d <- fortify.zoo(x)
matplot(d[[1]], d[-1], xlab = "Time")

Note

Lines <- "                 Elapsed Time  Total Inflow  Total Evap  Surface Infil
    2021-04-30 10:02:00        0.033            0      0.125             0
    2021-04-30 10:04:00        0.067            0      0.125             0
    2021-04-30 10:06:00        0.100            0      0.125             0
    2021-04-30 10:08:00        0.133            0      0.125             0
    2021-04-30 10:10:00        0.167            0      0.125             0
    2021-04-30 10:12:00        0.200            0      0.125             0"

# split into lines, trim whitespace off ends, replace 2+ spaces w comma
L <- Lines |>
  textConnection() |>
  readLines() |>
  trimws() |>
  gsub(pattern = "  +", replacement = ",")

z <- read.csv.zoo(text = L, index = 0, tz = "", check.names = FALSE)
x <- as.xts(z)

and `library(rtsplot); rtsplot(x, xlab = "Time")` – phiver Dec 24 '21 at 14:58 — phiver, Dec 24 '21 at 14:58

xts format assign name for index column

2 Answers2

Note