zoo Reference Card

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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.

Creation of regular series

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(). |

Standard methods

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.

Import/export

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.

Coercion

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".

Merging and binding

merge: Union, intersection, left join, right join along indexes.
cbind: Column binding along the intersection of the index.
c, rbind: Combining/row binding (indexes may not overlap).
aggregate: Compute summary statistics along a coarser grid of indexes

Mathematical operations

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().

Extracting and replacing data and index

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.

`NA` handling

na.omit: Omit NAs.
na.contiguous: Compute longest sequence of non-NA observations.
na.fill: Impute NAs by filling gaps with specific values.
na.locf: Impute NAs by carrying forward the last observation.
na.approx, na.spline: Impute NAs by interpolation.
na.trim: Remove leading and/or trailing NAs.

Rolling analytics

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.

Methods for regular series

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.

Time classes for monthly and quarterly data

yearmon: Time index class for monthly data.
yearqtr: Time index class for quarterly data.

These binaries (installable software) and packages are in development.
They may not be fully stable and should be used with caution. We make no claims about them.
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zoo Reference Card

Creation

Creation of regular series

Standard methods

Import/export

Coercion

Merging and binding

Mathematical operations

Extracting and replacing data and index

NA handling

Rolling analytics

Methods for regular series

Time classes for monthly and quarterly data

`NA` handling