Week 7 glossary

Week 7 glossary#

Online resources#

Documentation of xarray can be found at https://docs.xarray.dev/en/stable/api.html

A good guide on color maps can be found at https://matplotlib.org/stable/users/explain/colors/colormaps.html

A quick guide of color maps from the cmocean package can be found at https://matplotlib.org/cmocean/

Xarray#

Xarray functions#

  • xr.open_dataset(): read netCDF file into an xarray Dataset object

  • xr.Dataset.from_dataframe(): convert a pandas DataFrame into an xarray Dataset object

  • xr.concat(): combine multiple Datasets or DataArrays into a single object

Xarray Dataset/DataArray attributes and syntax#

  • <Dataset>[]: extract a DataArray from a Dataset

  • <Dataset>.coords[] or <DataArray>.coords[]: extract coordinates of an xarray Dataset or DataArray

Xarray Dataset/DataArray methods#

  • <Dataset>.sel() or <DataArray>.sel(): subset a Dataset or DataArray by coordinate(s) value(s) of dimension(s)

  • <Dataset>.isel() or <DataArray>.isel(): subset a Dataset or DataArray by positional index(es) of dimension(s)

  • <Dataset>.mean() or <DataArray>.mean(): calculate the mean of a Dataset or DataArray along particular dimension(s)

  • <Dataset>.median() or <DataArray>.median(): calculate the median of a Dataset or DataArray along particular dimension(s)

  • <Dataset>.min() or <DataArray>.min(): calculate the minimum of a Dataset or DataArray along particular dimension(s)

  • <Dataset>.max() or <DataArray>.max(): calculate the maximum of a Dataset or DataArray along particular dimension(s)

  • <Dataset>.sum() or <DataArray>.sum(): calculate the sum of a Dataset or DataArray along particular dimension(s)

  • <Dataset>.var() or <DataArray>.var(): calculate the variance of a Dataset or DataArray along particular dimension(s)

  • <Dataset>.std() or <DataArray>.std(): calculate the standard deviation of a Dataset or DataArray along particular dimension(s)

  • <Dataset>.squeeze() or <DataArray>.squeeze(): remove coordinate(s) of size 1 from the internal array structure

  • <Dataset>.to_dataframe(): convert an xarray Dataset into a pandas DataFrame

  • <Dataset>.to_netcdf(): convert an xarray Dataset into an external netCDF file

  • <Dataset>.expand_dims() or <DataArray>.expand_dims(): add addition dimension(s) to a Dataset or DataArray

  • <Dataset>.assign_coords() or <DataArray>.assign_coords(): assign coordinates to dimension(s) of a Dataset or DataArray

Numpy functions on Dataset/DataArray#

  • np.sqrt(), np.exp(), np.sin(), etc.: apply numpy mapping function on DataArray

Pandas DataFrame methods#

  • <DataFrame>.set_index(): set particular column(s) as the index of a DataFrame

  • <DataFrame>.reset_index(): reset the index of a DataFrame as a regular column

Matplotlib for 2D gridded data#

  • <Axes>.pcolormesh(): false-color plot for 2D gridded data

  • <Axes>.contourf(): filled contour plot for 2D gridded data

  • <Axes>.contour(): line contour plot for 2D gridded data

  • <Figure>.colorbar(): create color bar in a figure

  • <Colorbar>.set_label(): set the label of the color bar

  • <Colorbar>.ax: obtain the Axes instance of the color bar

  • <ContourSet>.clabel(): create labels within the contour lines

Color maps from the cmocean module#

  • cmocean.cm.thermal, etc.: color maps for oceanographic data

Contents