read.zoo and write.zoo are convenience functions for reading
and writing "zoo" series from/to text files. They are convenience
interfaces to read.table and write.table, respectively.
To employ read.csv, read.csv2, read.delim,
read.delim2 instead of read.table additional functions
read.csv.zoo etc. are provided.
read.zoo(file, format = "", tz = "", FUN = NULL,
regular = FALSE, index.column = 1, drop = TRUE, FUN2 = NULL,
split = NULL, aggregate = FALSE, ..., text, read = read.table)
write.zoo(x, file = "", index.name = "Index", row.names = FALSE, col.names = NULL, ...)read.csv.zoo(..., read = read.csv)
read.csv2.zoo(..., read = read.csv2)
read.delim.zoo(..., read = read.delim)
read.delim2.zoo(..., read = read.delim2)
read.zoo returns an object of class "zoo" (or "zooreg").
character string or strings giving the name of the file(s)
which the data
are to be read from/written to. See read.table and
write.table for more information. Alternatively,
in read.zoo, file can be a connection or a
data.frame (e.g.,
resulting from a previous read.table call) that
is subsequently processed to a "zoo" series.
date format argument passed to FUN.
time zone argument passed to as.POSIXct.
a function for computing the index from the first column of the data. See details.
logical. Should the series be coerced to class "zooreg"
(if the series is regular)?
numeric vector or list. The column names or numbers of the data frame
in which the index/time is stored. If the read.table argument colClasses
is used and "NULL" is among its components then
index.column refers to the column numbers after the columns
corresponding to "NULL" in colClasses have been removed.
If specified as a list then one argument will be passed to argument FUN per component so that,
for example, index.column = list(1, 2) will cause
FUN(x[,1], x[,2], ...) to be called whereas
index.column = list(1:2) will cause
FUN(x[,1:2], ...) to be called where x is a data frame of
characters data. Here ... refers to format
and/or tz, if they specified as arguments. index.column = 0 can
be used to specify that the row names be used as the index. In the case that
no row names were input sequential numbering is used.
If index.column is specified as an ordinary vector then if it has the
same length as the number of arguments of FUN (or FUN2 in the
event that FUN2 is specified and FUN is not)
then index.column is converted to a
list. Also it is always converted to a list if it has length 1.
logical. If the data frame contains just a single data column, should the second dimension be dropped?
a "zoo" object.
character with name of the index column in the written data file.
logical. Should row names be written? Default is FALSE
because the row names are just character representations of the index.
logical. Should column names be written? Default is to
write column names only if x has column names.
function. It is applied to the time index after
FUN and before aggregate. If FUN is not specified
but FUN2 is specified then only FUN2 is applied.
NULL or column number or name or vector of numbers or
names. If not NULL then the data is assumed to be in long format and is
split according to the indicated columns. See the R
reshape command for description of long data.
If split = Inf then the first of each run among the times are made into
a separate series, the second of each run and so on. If split= -Inf then
the last of each run is made into a separate series, the second last
and so on.
logical or function. If set to TRUE, then aggregate.zoo
is applied to the zoo object created to compute the mean of all values with
the same time index. Alternatively, aggregate can be set to any other
function that should be used for aggregation.
If FALSE (the default), no aggregation is performed and a warning
is given if there are any duplicated time indexes. Note that most
zoo functions do not accept objects with duplicate time indexes.
See aggregate.zoo.
further arguments passed to other functions. In the read.*.zoo
the arguments are passed to the function specified in read
(unless file is a data.frame already). In write.zoo the
arguments are passed to write.table.
character. If file is not supplied and this is, then
data are read from the value of text via a text connection.
See below for an example.
function. The function for reading file (unless it is
a data.frame already).
read.zoo is a convenience function which should make it easier
to read data from a text file and turn it into a "zoo" series
immediately. read.zoo reads the data file via read.table(file, ...).
The column index.column (by default the first) of the resulting data is
interpreted to be the index/time, the remaining columns the corresponding data.
(If the file only has only column then that is assumed to be the data column and
1, 2, ... are used for the index.) To assign the appropriate class
to the index, FUN can be specified and is applied to the first column.
To process the index, read.zoo calls FUN with the index as the
first argument. If FUN is not specified, the following default is employed:
(a) If file is a data frame with a single
index column that appears to be a time index already, then FUN = identity is used.
The conditions for a readily produced time index are: It is not character or
factor (and the arguments tz and format must not be specified).
(b) If the conditions from (a) do not hold then the following strategy is used.
If there are multiple index columns they are pasted together with a space between each.
Using the (pasted) index column: (1) If tz is specified then the
index column is converted to POSIXct. (2) If format is specified
then the index column is converted to Date. (3) Otherwise, a heuristic
attempts to decide between "numeric", "POSIXct", and "Date" by
trying them in that order (which may not always succeed though). By default,
only the standard date/time format is used. Hence, supplying format and/or tz
is necessary if some date/time format is used that is not the default. And even
if the default format is appropriate for the index, explicitly supplying
FUN or at least format and/or tz typically leads to more
reliable results than the heuristic.
If regular is set to TRUE and the resulting series has an
underlying regularity, it is coerced to a "zooreg" series.
To employ other functions than read.table to read the initial data,
further convenience interfaces read.csv.zoo etc. are provided.
write.zoo is a convenience function for writing "zoo" series
to text files. It first coerces its argument to a "data.frame", adds
a column with the index and then calls write.table.
See also vignette("zoo-read", package = "zoo") for detailed examples.
zoo