A repaid Statistical Analysis tool for Climate or Meteorology data.

SACPY -- A Python Package for Statistical Analysis of Climate

Sacpy, a repaid Statistical Analysis tool for Climate or Meteorology data.

Author : Zilu Meng

e-mail : mzll1202@163.com

github : https://github.com/ZiluM/sacpy

examples or document : https://github.com/ZiluM/sacpy/tree/master/examples

version : 0.0.8

Why choose Sacpy?

Quick!

For example, Sacpy is more than 60 times faster than the traditional regression analysis with Python (see speed test).

Turn to climate data customization!

Compatible with commonly used meteorological calculation libraries such as numpy and xarray.

Install

    pip install sacpy


Example

example1

Calculate the correlation between SST and nino3.4 index

import numpy as np
import scapy as scp
import matplotlib.pyplot as plt

# get ssta (method=1, Remove linear trend;method=0, Minus multi-year average)
ssta = scp.get_anom(sst,method=1)
# calculate Nino3.4
Nino34 = ssta.loc[:,-5:5,190:240].mean(axis=(1,2))
# regression
linreg = scp.LinReg(np.array(Nino34),np.array(ssta))
# plot
plt.contourf(linreg.corr)
# Significance test
plt.contourf(linreg.p_value,levels=[0, 0.05, 1],zorder=1,
hatches=['..', None],colors="None",)
# save
plt.savefig("./nino34.png")


Result(For a detailed drawing process, see example):

example2

multiple linear regression on Nino3.4 IODIdex and ssta pattern

import numpy as np
import scapy as scp
import matplotlib.pyplot as plt

# get ssta (method=1, Remove linear trend;method=0, Minus multi-year average)
ssta = scp.get_anom(sst,method=1)
# calculate Nino3.4
Nino34 = ssta.loc[:,-5:5,190:240].mean(axis=(1,2))
# calculate IODIdex
IODW = ssta.loc[:,-10:10,50:70].mean(axis=(1,2))
IODE = ssta.loc[:,-10:0,90:110].mean(axis=(1,2))
IODI = +IODW - IODE
# get x
X = np.vstack([np.array(Nino34),np.array(IODI)]).T
# multiple linear regression
MLR = scp.MultLinReg(X,np.array(ssta))
# plot IOD's effect
plt.contourf(MLR.slope[1])
# Significance test
plt.contourf(MLR.pv_i[1],levels=[0, 0.1, 1],zorder=1,
hatches=['..', None],colors="None",)
plt.savefig("../pic/MLR.png")


Result(For a detailed drawing process, see example):

Speed

As a comparison, we use the corr function in the xarray library, corrcoef function in numpy library and for-loop. The time required to calculate the correlation coefficient between SSTA and nino3.4 for 50 times is shown in the figure below.

It can be seen that we are five times faster than xarray.corr, 60 times faster than forloop and 200 times faster than numpy.corrcoef.

Moreover, xarray and numpy can not return the p value. We can simply check the pvalue attribute of sacpy to get the p value.

All in all, if we want to get p-value and correlation or slope, Sacpy is 60 times faster than before.

Acknowledgements

Thank Prof. Feng Zhu (NUIST,https://github.com/fzhu2e) for his guidance of this project

Change Log

Nothing!

version 0.0.5

First official edition

version 0.0.6

Updated the speed test and changed small errors

Project details

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