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Expand numeric range

Usage

expand_range(x, expand_fraction = 0.1, minimum_range = 0.01, ...)

Arguments

x

numeric vector, or list of numeric vectors. The input is converted to a range using range(x, na.rm=TRUE) to ensure no NA values are included. Note that this step will force the range to be in ascending order.

expand_fraction

numeric value indicating the fraction of the range defined by diff(range(x, na.rm=TRUE)) to add to the total range. When expand_fraction has only one value, it is applied across the whole range, which means each side is extended by half the expand_fraction. When expand_fraction contains two values, it is applied in order to the low, then high side of the numeric range, and each full expand_range value is applied.

minimum_range

numeric value indicating the minimum range of the output, useful when the input has zero range, for example if x=c(10, 10).

...

additional arguments are ignored.

Value

numeric vector, or when input x is list the output will also be a list of numeric vectors. The numeric vector will contain the range after expansion.

Details

This function takes a numeric range (or numeric vector and calculates its range) and expands this range by a fraction given by expand_fraction.

When the input range is zero, the minimum absolute range can be given by minimum_range.

The input may be a list that contains numeric vectors, in which case the list will be iterated to produce an expanded range for each numeric vector. Each numeric vector is expanded independently.

This function is intended to be a simple technique to expand x-axis and y-axis ranges of a graphical plot.

Examples

x <- c(0, 10);

# expand the total range by 0.1
expand_range(x, 0.1);
#> [1] -0.5 10.5

# the original range is 10 units
diff(x);
#> [1] 10

# the expanded range is 11 units
diff(expand_range(x, 0.1));
#> [1] 11

# expand one side but not the other
expand_range(x, c(0.1, 0));
#> [1] -1 10
# this new range is 11 units
diff(expand_range(x, c(0.1, 0)))
#> [1] 11

# input with no range is extended to some minimum value
expand_range(1, minimum_range=1)
#> [1] 0.5 1.5
expand_range(1, minimum_range=c(1, 0))
#> [1] 0 1

# list input is iterated, for example xlim, ylim
xlim <- c(1, 10)
ylim <- c(1, 100)
expand_range(list(xlim=xlim, ylim=ylim))
#> $xlim
#> [1]  0.55 10.45
#> 
#> $ylim
#> [1]  -3.95 104.95
#>