Presto 0.100 Documentation

5.14. 颜色函数

5.14. 颜色函数

bar(x, width) → varchar

Renders a single bar in an ANSI bar chart using a default low_color of red and a high_color of green. For example, if x of 25% and width of 40 are passed to this function. A 10-character red bar will be drawn followed by 30 spaces to create a bar of 40 characters.

bar(x, width, low_color, high_color) → varchar

Renders a single line in an ANSI bar chart of the specified width. The parameter x is a double value between [0,1]. Values of x that fall outside the range [0,1] will be truncated to either a 0 or a 1 value. The low_color and high_color capture the color to use for either end of the horizontal bar chart. For example, if x is 0.5, width is 80, low_color is 0xFF0000, and high_color is 0x00FF00 this function will return a 40 character bar that varies from red (0xFF0000) and yellow (0xFFFF00) and the remainder of the 80 character bar will be padded with spaces.

../_images/functions_color_bar.png
color(string) → color

Returns a color capturing a decoded RGB value from a 4-character string of the format “#000”. The input string should be varchar containing a CSS-style short rgb string or one of black, red, green, yellow, blue, magenta, cyan, white.

color(x, low, high, low_color, high_color) → color

Returns a color interpolated between low_color and high_color using the double parameters x, low, and high to calculate a fraction which is then passed to the color(fraction, low_color, high_color) function shown below. If x falls outside the range defined by low and high it’s value will be truncated to fit within this range.

color(x, low_color, high_color) → color

Returns a color interpolated between low_color and high_color according to the double argument x between 0 and 1.0. The parameter x is a double value between [0,1]. Values of x that fall outside the range [0,1] will be truncated to either a 0 or a 1 value.

render(x, color) → varchar

使用指定的颜色对 x 渲染,使用ANSI标准颜色代码。 x 可以是double、bigint或varchar类型。

render(b) → varchar

Accepts boolean value b and renders a green true or a red false using ANSI color codes.

rgb(red, green, blue) → color

Returns a color value capturing the RGB value of three component color values supplied as int parameters ranging from 0 to 255: red, green, blue.