apply_thr: Apply Thresholds

In lsigut/openeddy: Post-process eddy covariance data with ease

Apply Thresholds

Description

Values of x are checked against the specified thresholds to obtain their quality control (QC) flags.

Usage

apply_thr(
  x,
  thr,
  name_out = "-",
  flag = c("higher", "outside", "between", "lower"),
  angles = FALSE
)

Arguments

x	A numeric atomic type with NULL dimensions.
thr	A numeric vector of length two or list with two numeric vectors of length two. If vector, first (second) element provides lower (upper) boundary threshold for quality control flag 2. If list, first (second) element provides lower (upper) boundary threshold for quality control flag 1 and 2. This is reversed for flag = "lower". See examples.
name_out	A character string providing varnames attribute value of the output.
flag	A character string. Selects one of the available flagging approaches. Can be abbreviated. See 'Details'.
angles	A logical value. Choose if x represents angles.

Details

This function is called by extract_QC but can be useful on its own when filtering values of variable according to the 0 - 2 QC flag scheme.

Obtained QC flags are assigned in the range 0 - 2 according to these rules:

For flag = "higher"

• If x <= thr[1], QC flag = 0.

• If x > thr[1] & x <= thr[2], QC flag = 1.

• If x > thr[2], QC flag = 2.

For flag = "outside" (thr supplied as vector)

• If x >= thr[1] & x <= thr[2], QC flag = 0.

• If x < thr[1] | x > thr[2], QC flag = 2.

For flag = "outside" (thr supplied as list)

• If x >= thr[[1]][2] & x <= thr[[2]][1], QC flag = 0.

• If x < thr[[1]][2] | x > thr[[2]][1], QC flag = 1.

• If x < thr[[1]][1] | x > thr[[2]][2], QC flag = 2.

For flag = "between" (thr supplied as vector)

• If x <= thr[1] | x >= thr[2], QC flag = 0.

• If x > thr[1] & x < thr[2], QC flag = 2.

For flag = "between" (thr supplied as list)

• If x <= thr[[1]][1] | x >= thr[[2]][2], QC flag = 0.

• If x > thr[[1]][1] & x < thr[[2]][2], QC flag = 1.

• If x > thr[[1]][2] & x < thr[[2]][1], QC flag = 2.

For flag = "lower"

• If x >= thr[1], QC flag = 0.

• If x < thr[1] & x >= thr[2], QC flag = 1.

• If x < thr[2], QC flag = 2.

In case of angles = TRUE, conditions are appropriately implemented on the circular scale. Angles are expected to be within the range [0, 360) degrees and corrected otherwise. Notice that using flag = "higher" or flag = "lower" might not be very useful on the circular scale.

Value

An integer vector with the same length as x. Its varnames and units attributes are set to name_out and "-" values, respectively.

See Also

extract_QC.

Examples

# flag defaults to "higher"
apply_thr(1:10, c(3, 6), "example")

# comparison of flag types
xx <- data.frame(var = 1:10)
xx$higher <- apply_thr(xx$var, c(3, 6), "higher", flag = "higher")
xx$outside_c <- apply_thr(xx$var, c(4, 6), "outside_c", flag = "outside")
xx$outside_l <- apply_thr(xx$var, list(c(2, 4), c(6, 8)), "outside_l",
                          flag = "outside")
xx$between_c <- apply_thr(xx$var, c(4, 6), "between_c", flag = "between")
xx$between_l <- apply_thr(xx$var, list(c(2, 4), c(6, 8)), "between_l",
                          flag = "between")
xx$lower <- apply_thr(xx$var, c(6, 3), "lower", flag = "lower")
xx
str(xx)

# flagging for angles
# - 'higher' and 'lower' flags are problematic on a circular scale
yy <- data.frame(var = 170:180)
# expected results because thresholds are not crossing zero (360 deg)
yy$higher <- apply_thr(yy$var, c(172, 176), "higher", flag = "higher",
                       angle = TRUE)
yy$outside_c <- apply_thr(yy$var, c(174, 176), "outside_c", flag = "outside",
                          angle = TRUE)
yy$outside_l <- apply_thr(yy$var, list(c(172, 174), c(176, 178)), "outside_l",
                          flag = "outside", angle = TRUE)
yy$between_c <- apply_thr(yy$var, c(174, 176), "between_c", flag = "between",
                          angle = TRUE)
yy$between_l <- apply_thr(yy$var, list(c(172, 174), c(176, 178)), "between_l",
                          flag = "between", angle = TRUE)
# expected results because thresholds are not crossing zero (360 deg)
yy$lower <- apply_thr(yy$var, c(176, 172), "lower", flag = "lower",
                      angle = TRUE)
yy
str(yy)

# flagging for angles with thresholds crossing zero (360 deg)
zz <- data.frame(var = c(355:359, 0:5))
# thresholds crossing zero (360 deg) - not useful (but valid) results
zz$higher <- apply_thr(zz$var, c(357, 1), "higher", flag = "higher",
                       angle = TRUE)
zz$outside_c <- apply_thr(zz$var, c(359, 1), "outside_c", flag = "outside",
                          angle = TRUE)
zz$outside_l <- apply_thr(zz$var, list(c(357, 359), c(1, 3)), "outside_l",
                          flag = "outside", angle = TRUE)
zz$between_c <- apply_thr(zz$var, c(359, 1), "between_c", flag = "between",
                          angle = TRUE)
zz$between_l <- apply_thr(zz$var, list(c(357, 359), c(1, 3)), "between_l",
                          flag = "between", angle = TRUE)
# thresholds crossing zero (360 deg) - not useful (but valid) results
zz$lower <- apply_thr(zz$var, c(1, 357), "lower", flag = "lower",
                      angle = TRUE)
zz
str(zz)

lsigut/openeddy documentation built on Aug. 5, 2023, 12:25 a.m.