The labels style reads coordinates and text from a data file and places the text string at the corresponding 2D or 3D position. 3 or 4 input columns of basic data are required. Additional input columns may be used to provide information such as variable font size or text color (see `rgbcolor variable`).
3 columns: x y string # 2D version
4 columns: x y z string # 3D version
The font, color, rotation angle and other properties of the printed text may be specified as additional command options (see `set label`). The example below generates a 2D plot with text labels constructed from the city whose name is taken from column 1 of the input file, and whose geographic coordinates are in columns 4 and 5. The font size is calculated from the value in column 3, in this case the population.
CityName(String,Size) = sprintf("{/=%d %s}", Scale(Size), String)
plot 'cities.dat' using 5:4:(CityName(stringcolumn(1),$3)) with labels
If we did not want to adjust the font size to a different size for each city name, the command would be much simpler:
plot 'cities.dat' using 5:4:1 with labels font "Times,8"
The labels style can also be used in 3D plots. In this case four input column specifiers are required, corresponding to X Y Z and text.
splot 'datafile' using 1:2:3:4 with labels
See also `datastrings`, `set style data`.