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Version: Python

How to apply color formatting to columns in a table

This guide shows you how to apply various color formatting options to the columns in your static or dynamic tables.

Format an entire column

Color formatting can be applied to the contents of an entire column using the format_columns method:

.format_columns("columnName=<colorObject>")

  • columnName is the name of the column to format.
  • <colorObject> is any of the valid color objects available in Deephaven.

The following query will apply the color VIVID_YELLOW to all cells in the GPA column:

from deephaven import new_table
from deephaven.column import int_col, double_col, string_col

students = new_table([
string_col("Name", ["Andy", "Claire", "Jane", "Steven"]),
int_col("StudentID", [1, 2, 3, 4]),
int_col("TestGrade", [85, 95, 88, 72]),
int_col("HomeworkGrade", [85, 95, 90, 95]),
double_col("GPA", [3.0, 4.0, 3.7, 2.8])
]).format_columns(["GPA=VIVID_YELLOW"])

Format certain rows or columns

Columns

You can apply conditional formatting to only certain rows and/or columns.

The following method formats cells in the named column when a specified condition exists:

.format_column_where("columnName", "<condition>", "colorValue")

For example, the following query applies the color DEEP_GREEN to the TestGrade column when the value in the GPA column of the same row is less than 3.0.

students_format=students.format_column_where("TestGrade", "GPA<3.0", "DEEP_GREEN")

Ternary statements can also be used to color cells based on conditional statements. For example, the following query colors cells in the Name column BRIGHT_GREEN if the value in the Diff column is positive, and BRIGHT_RED if otherwise:

student_tests =  students_format\
.update("Diff = HomeworkGrade - TestGrade")\
.format_columns("Name = (Diff > 0) ? BRIGHT_GREEN : BRIGHT_RED")

Rows

The format_row_where method formats entire rows when a specified condition exists:

.format_row_where("<condition>", "<colorValue>")

The following query applies the color PALE_BLUE to any row when the value in the Diff column is greater than 0.

student_all_row =  student_tests\
.format_row_where("Diff > 0"," PALE_BLUE")

The following query colors the entire row BRIGHT_YELLOW if the Sym column is equal to the string "AAPL":

student_name = student_all_row.format_row_where("Name=`Jane`", "BRIGHT_YELLOW")

The following colors all the cells in every other row VIVID_PURPLE:

student_id = student_name.format_row_where("StudentID % 2 == 0", "VIVID_PURPLE")

Combinations

Color methods can also be combined in a table.

The following query colors all cells in every other row VIVID_PURPLE, and colors the cells in column C BRIGHT_YELLOW in every odd row.

students_combined = student_tests.format_row_where("StudentID % 2 == 0", "VIVID_PURPLE")\
.format_column_where("Name", "Diff > 0", "BRIGHT_YELLOW")

Heat Maps

Color-based formatting can also be used to create heat maps in Deephaven tables:

heatmap(<colName>, <minimumValue>, <maximumValue>, <minimumBackgroundColor>, <maximumBackgroundColor>)

The following query will apply color to the GPA column as follows:

  • When the value is less than or equal to 1.00, BRIGHT_GREEN will be used,
  • When the value is greater than or equal to 4.00, BRIGHT_RED will be used, and
  • An automatically interpolated color proportionally between BRIGHT_GREEN and BRIGHT_RED will be used for all other values between 1 and 4.
students_heat= students.format_columns("GPA = heatmap(GPA, 1, 4, BRIGHT_GREEN, BRIGHT_RED)")

Options are also available for heatmapFg() and heatmapForeground(). When either of these methods is used, the heatmap color pair listed in the argument is applied only to the foreground.

Assign colors to backgrounds and foregrounds

The field of a cell is the background. The text/numbers showing in the cell is the foreground. Color objects can then be used with the following methods to assign individual color values or combinations to the background and/or foreground:

  • bg() or background() - These methods set the background to a specific color, but do not apply any foreground color.
  • fg() or foreground() - These methods set the foreground to a specific color, but do not apply any background color.
  • bgfg() or backgroundForeground() - These methods set both the background and foreground to specific values.
  • bgfga() or backgroundForegroundAuto() - These methods set the background to a specific color. Deephaven automatically chooses a contrasting foreground color.
  • fgo() or foregroundOverride() - These methods are similar to fg() or foreground(). However, when either of these methods are used, the color selected will override the highlight color that is automatically assigned when the user highlights the cell or group of cells in the Deephaven console.
  • bgo() or backgroundOverride() - These methods are similar to bg() or background(). However, when either of these methods are used, the color selected will override the highlight color that is automatically assigned when the user highlights the cell or group of cells in the Deephaven console.
caution

Overriding the foreground or background colors may make the highlighted content difficult to read. Care in use is suggested.

The following query generates a table with an orange background using RGB values:

students_combined = student_tests\
.format_column_where("Name", "Diff > 0", "bg(colorRGB(255,93,0))")

The following query generates a table with a purple foreground using RGB values:

students_purple = students.format_row_where("true","fg(colorRGB(102,0,204))")

The following query will color the Name column with a hot pink background and a yellow foreground.

students_pink = students.format_columns("Name = bgfg(colorRGB(255,105,80),colorRGB(255,255,0))")

The following query generates a table with a navy blue background and automatically selects a contrasting foreground.

students_navy = students.format_columns("* = bgfga(colorRGB(0,0,128))")

Appendix: Assigning colors

Colors can be assigned in Deephaven tables or plots using strings or by using color objects.

Named color values

There are 280 predefined color values available in Deephaven.

These predefined colors are referred to by their names, which must be typed in capital letters.

Because these values are considered strings, they must be enclosed in quotes. If the named color values are to be used within another string (i.e., a string within a string), the name must be enclosed in backticks.

HEX (Hexadecimal)

Hexadecimal values are specified with three values that correspond to RRGGBB. Each value [RR (red), GG (green) and BB (blue)] are hexadecimal integers between 00 and FF, and they specify the intensity of the color. All Hex values are preceded with a pound sign, e.g., #0099FF.

Because these values are considered strings, they must be enclosed in quotes. If the HEX color values are to be used within another string (i.e., a string within a string), the name must be enclosed in backticks.

students_hex = students.format_columns("Name = `#87CEFA`")

RGB (Red, Green, Blue)

RGB values are represented numerically with comma-separated values for red, green and blue respectively, with each value expressed as integers in the range 0-255 or floats in the range 0-1.

RGB color values can be converted into color objects in Deephaven by enclosing their values into the argument of the colorRGB method.

The syntax follows:

colorRGB(int r, int g, int b)

colorRGB(float r, float g, float b)

students_rgb = students.format_columns("Name = colorRGB(135, 206, 250)")

RGBA (Red, Green, Blue, Alpha)

The RGBA color model is based on RGB. However, RGBA provides an option for a fourth value to specify alpha (transparency). As with RGB, the numeric values can be specified using floats or ints. The numeric ranges for RGB remain the same. The alpha channel can range from 0 (fully transparent) to 255 (fully opaque) for ints, and 0.0 to 1.0 for floats.

RGBA color values can be converted into color objects in Deephaven by enclosing their values into the argument of the colorRGB method.

The syntax follows:

colorRGB(int r, int g, int b, int a)

colorRGB(float r, float g, float b, float a)

students_rgba = students.format_columns("Name = colorRGB(135, 206, 250, 50)")