R help - Jan 2018 - Plotting quarterly time series

I have a data set with quarterly time series for several variables. The
time index is recorded in column 1 of the dataframe as a character vector
"Q1 1961", "Q2 1961","Q3 1961", "Q4
1961", "Q1 1962", etc. I want to
produce line plots with ggplot2, but it seems I need to convert the time
index from character to date class. Is that right? If so, how do I make
the conversion?

On Sun, 28 Jan 2018, phil at philipsmith.ca wrote:
> I have a data set with quarterly time series for several variables. The 
> time index is recorded in column 1 of the dataframe as a character 
> vector "Q1 1961", "Q2 1961","Q3 1961",
"Q4 1961", "Q1 1962", etc. I want
> to produce line plots with ggplot2, but it seems I need to convert the 
> time index from character to date class. Is that right? If so, how do I 
> make the conversion?
You can use the yearqtr class in the zoo package, converting with 
as.yearqtr(..., format = "Q%q %Y"). zoo also provides an autoplot()
method
for ggplot2-based time series visualizations. See ?autoplot.zoo for 
various examples.

## example data similar to your description
d <- data.frame(sin = sin(1:8), cos = cos(1:8))
d$time <- c("Q1 1961", "Q2 1961", "Q3 1961",
"Q4 1961", "Q1 1962",
   "Q2 1962", "Q3 1962", "Q4 1962")

## convert to zoo series
library("zoo")
z <- zoo(as.matrix(d[, 1:2]), as.yearqtr(d$time, "Q%q %Y"))

## ggplot2 display
library("ggplot2")
autoplot(z)

## with nicer axis scaling
autoplot(z) + scale_x_yearqtr()

## some variations
autoplot(z, facets = Series ~ .) + scale_x_yearqtr() + geom_point()
autoplot(z, facets = NULL) + scale_x_yearqtr() + geom_point()

> ______________________________________________
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http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>

Using Achim's d this also works to generate z where FUN is a function used
to transform the index column and format is also passed to FUN.

z <- read.zoo(d, index = "time", FUN = as.yearqtr, format =
"Q%q %Y")

On Sun, Jan 28, 2018 at 4:53 PM, Achim Zeileis <Achim.Zeileis at
uibk.ac.at> wrote:
> On Sun, 28 Jan 2018, phil at philipsmith.ca wrote:
>
>> I have a data set with quarterly time series for several variables. The
>> time index is recorded in column 1 of the dataframe as a character
vector
>> "Q1 1961", "Q2 1961","Q3 1961", "Q4
1961", "Q1 1962", etc. I want to produce
>> line plots with ggplot2, but it seems I need to convert the time index
from
>> character to date class. Is that right? If so, how do I make the
conversion?
>
>
> You can use the yearqtr class in the zoo package, converting with
> as.yearqtr(..., format = "Q%q %Y"). zoo also provides an
autoplot() method
> for ggplot2-based time series visualizations. See ?autoplot.zoo for various
> examples.
>
> ## example data similar to your description
> d <- data.frame(sin = sin(1:8), cos = cos(1:8))
> d$time <- c("Q1 1961", "Q2 1961", "Q3
1961", "Q4 1961", "Q1 1962",
>   "Q2 1962", "Q3 1962", "Q4 1962")
>
> ## convert to zoo series
> library("zoo")
> z <- zoo(as.matrix(d[, 1:2]), as.yearqtr(d$time, "Q%q %Y"))
>
> ## ggplot2 display
> library("ggplot2")
> autoplot(z)
>
> ## with nicer axis scaling
> autoplot(z) + scale_x_yearqtr()
>
> ## some variations
> autoplot(z, facets = Series ~ .) + scale_x_yearqtr() + geom_point()
> autoplot(z, facets = NULL) + scale_x_yearqtr() + geom_point()
>
>
>
>> ______________________________________________
>> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
>> https://stat.ethz.ch/mailman/listinfo/r-help
>> PLEASE do read the posting guide
>> http://www.R-project.org/posting-guide.html
>> and provide commented, minimal, self-contained, reproducible code.
>>
>
> ______________________________________________
> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.


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