zoo Reference Card

Creation

zoo(x, order.by): Creation of a "zoo" object from the observations x (a vector or a matrix) and an index order.by by which the observations are ordered.

For computations on arbitrary index classes, methods to the following generic functions are assumed to work: combining c(), querying length length(), subsetting [, ordering ORDER() and value matching MATCH(). For pretty printing an as.character and/or index2char method might be helpful.

zoo(x, order.by, freq): Works as above but creates a "zooreg" object which inherits from "zoo" if the frequency freq complies with the index order.by. An as.numeric method has to be available for the index class.
zooreg(x, start, end, freq): Creates a "zooreg" series with a numeric index as above and has (almost) the same interface as ts(). |

plot: Plotting. Alternatives: xyplot (lattice), autoplot (ggplot2), tinyplot.
lines: Adding a "zoo" series to a plot.
print: Printing.
summary: Summarizing (column-wise).
str: Displaying structure of "zoo" objects.
head, tail: Head and tail of "zoo" objects.

read.zoo: Reads "zoo" objects from text files, e.g., in CSV format (comma-separated values).
write.zoo: Writes "zoo" objects to text files such, e.g., in CSV format.

as.zoo: Coercion to "zoo" is available for objects of class "ts", "xts", "timeSeries", and many others.
as.class.zoo: Coercion from "zoo" to other classes. Includes methods for class in "matrix", "vector", "data.frame", "list", "ts", "xts", "timeSeries", and several others.
is.zoo: Querying wether an object is of class "zoo".

Ops: Group generic functions performed along the intersection of indexes.
t: Transposing (coerces to "matrix" before).
cumsum: Compute (columnwise) cumulative quantities: sums cumsum(), products cumprod(), maximum cummax(), minimum cummin().

index, time: Extract the index of a series.
index<-, time<-: Replace the index of a series.
coredata, coredata<-: Extract and replace the data associated with a "zoo" object.
lag: Lagged observations.
diff: Arithmetic and geometric differences.
start, end: Querying start and end of a series.
window, window<-: Subsetting of "zoo" objects using their index.

rollapply: Apply a function to rolling margin of an array.
rollmean: More efficient functions for computing the rolling mean, median and maximum are rollmean(), rollmedian() and rollmax(), respectively.

is.regular: Checks whether a series is weakly (or strictly if strict = TRUE) regular.
frequency, deltat: Extracts the frequency or its reciprocal value respectively from a series, for "zoo" series the functions try to determine the regularity and frequency in a data-driven way.
cycle: Gives the position in the cycle of a regular series.