emp_orth_fun {stxplore}

Computes empirical orthogonal functions using a dataframe or a stars object.

Description

Computes empirical orthogonal functions of the data. Function autoplot can plot the output.

Usage

emp_orth_fun(x, ...)

## S3 method for class 'data.frame'
emp_orth_fun(x, values_df, ...)

## S3 method for class 'stars'
emp_orth_fun(x, ...)

## S3 method for class 'emporthfun'
autoplot(
  object,
  EOF_num = 1,
  palette = "Spectral",
  only_EOF = FALSE,
  only_TS = FALSE,
  ...
)

Arguments

x

The dataframe or stars object. If it is a dataframe, then it should have the locations.

...

Other arguments currently ignored.

values_df

For dataframes: the dataframe of dimension length(times) x length(locations) containing the quantity of interest.

object

For autoplot: the output of the function ‘emp_orth_fun’.

EOF_num

For autoplot: the number of Empirical Orthogonal Functions (EOFs) to plot.

palette

The color palette. Default is Spectral.

only_EOF

For autoplot: if TRUE, only the spatial EOF function would be plotted.

only_TS

For autoplot: if TRUE, only the PC time series would be plotted. If both are set to FALSE, both plots would be displayed. Both cannot be set to TRUE.

Value

An emporthfun object with temporal PCs and spatial EOFs.

Examples

# dataframe example
data(SSTlonlatshort)
data(SSTdatashort)
data(SSTlandmaskshort)
delete_rows <- which(SSTlandmaskshort  ==  1)
SSTdatashort   <- SSTdatashort[-delete_rows, 1:396]
emp1 <- emp_orth_fun(SSTlonlatshort[-delete_rows,  ],
                     SSTdatashort)
autoplot(emp1,
         EOF_num = 1)


# stars example
library(dplyr)
library(stars)
# Create a stars object from a data frame
precip_df <- NOAA_df_1990[NOAA_df_1990$proc == 'Precip', ] %>%
  filter(date >= "1992-02-01" & date <= "1992-02-05")
precip <- precip_df[ ,c('lat', 'lon', 'date', 'z')]
st_precip <- st_as_stars(precip, dims = c("lon", "lat", "date"))
emp <- emp_orth_fun(st_precip)
autoplot(emp, only_TS = TRUE)