djnpy

Handy python utilities

airy.py

import airy

Functions for linear wave theory, including celerity, energy density, and group velocity

djn.py

import djn

Useful little tidbits:

• uv2sd() convert east, north components to speed, direction
• sd2uv() convert speed, direction, to east, north components
• boxoff() a Matlab-like box off function for matplotlib
• twinboxoff() a Matlab-like box off function for matplotlib with twin y axes
• thinspines() make thinner matplotlib plot spines (default linewidth 0.5)
• find_nearest() find nearest value to the requested value in a numpy array
• middles() given a vector of bin edges of length n, make a vector of the middle values with length n-1.
• show() like plt.show() but for plotly. Makes it easy to turn a matplotlib plot into a plotly plot.
• set_fontsize() set fontsize of all elements of a figure, like djn.set_fontsize(plt.gcf(), 14)
• getcols() return default color order for matplotlib plots
• nextcolor() return the next color in the default matplotlib color order
• splabel() plot a subplot letter label like "(a)" in figures
• siegel() compute robust regression using repeated medians, following Siegel (1982). From Vlad Niculae.
• princax() compute principal axis, rotation axis, and principal ellipse for velocity data. From Rich Signell.
• rot_earth() rotate vectors u, v by given number of degrees using earthwise coordinates (0=N, 90=E)
• tidalfilt() low-pass filter data using a 5th order Butterworth filter. Useful for tidally filtering data.
• get_nan_block_idxs() return start and stop indexes of (by default) nan blocks`
• xcorr() cross-correlate data
• haversine() calculate the great circle distance in kilometers between two points on the earth (specified in decimal degrees)
• argmaxn() return largest N values from array
• math2geo(), geo2math() convert from math notation to geographic coordinates (degrees) and vice-versa
• scalebar() add scalebar to cartopy figure

matlabtools.py

import matlabtools

Functions to interact with .mat files created by MATLAB. Some functions based on code originally written by J.Paul Rinehimer.

• loadmat() load .mat file
• savemat() save .mat file
• matlab2datetime() convert MATLAB serial time to Python datetime, optionally with timezone
• datetime2matlab() convert Python datetime to MATLAB serial time

mesowest.py

import mesowest

• mesowest_to_xarray() convert a dictionary of data returned by the MesoPy package to an xarray Dataset

noaa.py

import noaa

• get_coops_data() Read data (water level, air pressure, wind, etc) from NOAA COOPS/Tides and Currents sites via the API as a dict
• get_long_coops_data() Read data longer than one month and return as an xarray Dataset

nwis.py

import nwis

• nwis_json() Obtain USGS NWIS data (like water level, discharge, meteorological data, etc) via JSON and return it as a Pandas DataFrame or xarray Datasaet

wavenumber.py

import wavenumber

A couple of functions to compute wavenumber from linear wave theory