On Wed, 19 Mar 2014, Rich Shepard wrote:
I need to plot and analyze irregular time series. Despite reading the 2005
JSS article on zoo, ?zoo, ?plot.zoo, and the quickref vignette I'm still not
doing this correctly. dput() output of a matrix and the zoo object are at
the end of this message.
It's sufficient to send such messages once even if others don't reply
within minutes.
My work flow is to read the *.csv file to create a data.frame, subset
the df to yield a date/data file for each constituent, convert the
subset df to a matrix using as.matrix() (see s95.ec.txt attached), then
create a zoo object specifying 'sampdate' as the order.by index. The
result is the second attachment (s95.ec.z.txt) which does not appear
correct to me.
Please have a look at read.zoo() and the accompanying "read.zoo" vignette
which does exactly what you are looking for (reading .csv files and
turning it into a zoo series).
Of the several zoo methods involving NA values, none of the imputations
seem appropriate for my data as there is neither pattern or sufficiently
short gaps between observed values, so I chose 'na.omit.' Putting that in
the command, e.g., s95.ec.z <- zoo(s95.ec, order.by = 'sampdate', na.omit)
produced an error:
s95.ec.z <- zoo(s95.ec, order.by = 'sampdate', na.omit)
Error in frequency > 1 :
comparison (6) is possible only for atomic and list types
I suspect that the first hurdle I need to overcome is correctly
creating a zoo object from the matrix.
Yes. The first argument should be a numeric vector or matrix and the
second argument should be something suitable as a time index. In your case
s95.ec is a data.frame with two "character" columns which is not suitable
directly. This works:
s95.ec.z <- zoo(as.numeric(s95.ec[,2]), order.by = as.Date(s95.ec[,1]))
plot(s95.ec.z)
But the route via read.zoo should be more convenient, I guess.
All the data I analyze have irregular collection dates and I need to
become fluent with zoo objects so I can correctly analyze and plot the time
series of these data.
Rich
<s95.ec.txt>++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
structure(c("1992-03-12", "1992-04-22", "1992-05-22", "1992-06-03",
"1992-11-06", "1993-01-28", "1993-02-18", "1993-03-03", "1993-03-15",
"1993-04-08", "1993-04-30", "1993-05-11", "1993-05-27", "1993-06-10",
"1993-06-25", "1993-07-09", "1993-07-31", "1994-03-28", "1994-04-07",
"1994-04-26", "1994-05-27", "1994-06-23", "1995-04-11", "1995-04-29",
"1995-05-30", "1995-06-23", "1995-07-26", "1995-12-04", "1996-01-16",
"1996-05-07", "1996-06-05", "1996-07-02", "1997-04-30", "1997-05-14",
"1997-06-16", "1997-07-29", "1998-05-25", "1998-05-28", "1998-07-27",
"1998-09-15", "1998-10-21", "1998-11-24", "1999-05-10", "1999-05-25",
"1999-06-22", "1999-07-22", "1999-11-09", "1999-12-01", "2000-03-04",
"2000-03-10", "2000-04-21", "2000-05-09", "2000-06-28", "2000-11-27",
"2000-12-07", "2001-02-16", "2001-03-07", "2001-04-30", "2001-05-11",
"2001-06-25", "2002-05-04", "2002-06-21", "2003-05-03", "2003-06-15",
"2004-06-28", "2004-07-01", " 85", " 80", " 85", NA, " 90", "110", " 90",
"100", "875", " 85", " 83", " 75", " 49", " 65", " 57", " 55", " 64", " 60",
" 80", " 80", " 45", " 65", " 83", " 60", " 40", " 62", " 80", "119", " 55",
" 65", " 44", " 48", " 68", " 43", " 50", " 70", " 52", " 45", " 66", " 92",
" 92", "134", " 77", " 52", "382", " 72", " 83", " 78", " 78", " 77", " 62",
" 51", " 59", " 79", " 65", " 77", " 81", " 59", " 55", " 67", " 67", " 16",
" 70", NA, " 42", " 42"), .Dim = c(66L, 2L), .Dimnames = list(
c("1", "2", "3", "4", "5", "6", "7", "8", "9", "10", "11",
"12", "13", "14", "15", "16", "17", "18", "19", "20", "21",
"22", "23", "24", "25", "26", "27", "28", "29", "30", "31",
"32", "33", "34", "35", "36", "37", "38", "39", "40", "41",
"42", "43", "44", "45", "46", "47", "48", "49", "50", "51",
"52", "53", "54", "55", "56", "57", "58", "59", "60", "61",
"62", "63", "64", "65", "66"), c("sampdate", "EC")))
<s95.ex.z.txt>+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
structure(c("1992-03-12", " 85"), .Dim = 1:2, .Dimnames = list(
"1", c("sampdate", "EC")), index = "sampdate", class = "zoo")
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
