#observable # Observable Plot [Main Plot page](https://observablehq.com/plot/) This is the summary page of my learnings of Observable Plot, a Javascript library to generate beautiful graphs. ## Scales > In Plot, the [mark](https://observablehq.com/plot/features/marks) binds channels to scales >Scales aren’t limited to horizontal and vertical position. They can also output to color, radius, length, opacity, and more. > https://observablehq.com/plot/features/scales - **linear** (default) - linear transform (translate and scale) - **pow** - power (exponential) transform - **sqrt** - square-root transform (_pow_ transform with exponent = 0.5) - **log** - logarithmic transform - **symlog** - bi-symmetric logarithmic transform per [Webber _et al._](https://www.researchgate.net/publication/233967063_A_bi-symmetric_log_transformation_for_wide-range_data) - **utc** (default, recommended) - UTC time - **time** - local time Often less used scale options - **domain** - typically [_min_, _max_], or an array of ordinal or categorical values - **range** - typically [_min_, _max_], or an array of ordinal or categorical values - **unknown** - the desired output value (defaults to undefined) for invalid input values - **reverse** - reverses the domain (or the range), say to flip the chart along _x_ or _y_ - **interval** - an interval or time interval (for interval data; see below) ## Data > Data comes in different types: quantitative (or temporal) values can be subtracted, ordinal values can be ordered, and nominal (or categorical) values can only be the same or different. > >Because nominal values often need some arbitrary order for display purposes — often alphabetical — Plot uses the term _ordinal_ to refer to both ordinal and nominal data. > https://observablehq.com/plot/features/marks#marks-imply-data-types ## Facets [Beautiful graphs](https://observablehq.com/plot/features/facets#facets) ## Projection (the world) Different types of ways to show the globe and geographic content - _conformal_ projections preserve angles and local shape, - _equal-area_ projections preserve area (use these for choropleths), - _equidistant_ projections preserve distance from one (or two) points, - _azimuthal_ projections expand radially from a central feature, - _cylindrical_ projections have symmetry around the axis of rotation, - the _stereographic_ projection preserves circles, and - the _gnomonic_ projection displays all great circles as straight lines!