Adding R squared value to scatter plot

J

Jamie Mitchell

I have made a plot using the following code:

python2.7
import netCDF4
import matplotlib.pyplot as plt
import numpy as np

swh_Q0_con_sw=netCDF4.Dataset('/data/cr1/jmitchel/Q0/swh/controlperiod/south_west/swhcontrol_swest_annavg1D.nc','r')
hs_Q0_con_sw=swh_Q0_con_sw.variables['hs'][:]
swh_Q3_con_sw=netCDF4.Dataset('/data/cr1/jmitchel/Q3/swh/controlperiod/south_west/swhcontrol_swest_annavg1D.nc','r')
hs_Q3_con_sw=swh_Q3_con_sw.variables['hs'][:]
swh_Q4_con_sw=netCDF4.Dataset('/data/cr1/jmitchel/Q4/swh/controlperiod/south_west/swhcontrol_swest_annavg1D.nc','r')
hs_Q4_con_sw=swh_Q4_con_sw.variables['hs'][:]
swh_Q14_con_sw=netCDF4.Dataset('/data/cr1/jmitchel/Q14/swh/controlperiod/south_west/swhcontrol_swest_annavg1D.nc','r')
hs_Q14_con_sw=swh_Q14_con_sw.variables['hs'][:]
swh_Q16_con_sw=netCDF4.Dataset('/data/cr1/jmitchel/Q16/swh/controlperiod/south_west/swhcontrol_swest_annavg1D.nc','r')
hs_Q16_con_sw=swh_Q16_con_sw.variables['hs'][:]
swh_Q0_fut_sw=netCDF4.Dataset('/data/cr1/jmitchel/Q0/swh/2050s/south_west/swh2050s_swest_annavg1D.nc','r')
hs_Q0_fut_sw=swh_Q0_fut_sw.variables['hs'][:]
swh_Q3_fut_sw=netCDF4.Dataset('/data/cr1/jmitchel/Q3/swh/2050s/south_west/swh2050s_swest_annavg1D.nc','r')
hs_Q3_fut_sw=swh_Q3_fut_sw.variables['hs'][:]
swh_Q4_fut_sw=netCDF4.Dataset('/data/cr1/jmitchel/Q4/swh/2050s/south_west/swh2050s_swest_annavg1D.nc','r')
hs_Q4_fut_sw=swh_Q4_fut_sw.variables['hs'][:]
swh_Q14_fut_sw=netCDF4.Dataset('/data/cr1/jmitchel/Q14/swh/2050s/south_west/swh2050s_swest_annavg1D.nc','r')
hs_Q14_fut_sw=swh_Q14_fut_sw.variables['hs'][:]
swh_Q16_fut_sw=netCDF4.Dataset('/data/cr1/jmitchel/Q16/swh/2050s/south_west/swh2050s_swest_annavg1D.nc','r')
hs_Q16_fut_sw=swh_Q16_fut_sw.variables['hs'][:]

fit_Q0_sw=np.polyfit(hs_Q0_con_sw,hs_Q0_fut_sw,1)
fit_fn_Q0_sw=np.poly1d(fit_Q0_sw)

plt.plot(hs_Q0_con_sw,hs_Q0_fut_sw,'g.')
plt.plot(hs_Q0_con_sw,fit_fn_Q0_sw(hs_Q0_con_sw),'g',label='Q0 no pert')

fit_Q3_sw=np.polyfit(hs_Q3_con_sw,hs_Q3_fut_sw,1)
fit_fn_Q3_sw=np.poly1d(fit_Q3_sw)

plt.plot(hs_Q3_con_sw,hs_Q3_fut_sw,'b.')
plt.plot(hs_Q3_con_sw,fit_fn_Q3_sw(hs_Q3_con_sw),'b',label='Q3 low sens')

fit_Q4_sw=np.polyfit(hs_Q4_con_sw,hs_Q4_fut_sw,1)
fit_fn_Q4_sw=np.poly1d(fit_Q4_sw)

plt.plot(hs_Q4_con_sw,hs_Q4_fut_sw,'y.')
plt.plot(hs_Q4_con_sw,fit_fn_Q4_sw(hs_Q4_con_sw),'y',label='Q4 low sens')

fit_Q14_sw=np.polyfit(hs_Q14_con_sw,hs_Q14_fut_sw,1)
fit_fn_Q14_sw=np.poly1d(fit_Q14_sw)

plt.plot(hs_Q14_con_sw,hs_Q14_fut_sw,'r.')
plt.plot(hs_Q14_con_sw,fit_fn_Q14_sw(hs_Q14_con_sw),'r',label='Q14 high sens')

fit_Q16_sw=np.polyfit(hs_Q16_con_sw,hs_Q16_fut_sw,1)
fit_fn_Q16_sw=np.poly1d(fit_Q16_sw)

plt.plot(hs_Q16_con_sw,hs_Q16_fut_sw,'c.')
plt.plot(hs_Q16_con_sw,fit_fn_Q16_sw(hs_Q16_con_sw),'c',label='Q16 high sens')

plt.legend(loc='best')
plt.xlabel('Significant Wave Height annual averages NW Scotland 1981-2010')
plt.ylabel('Significant Wave Height annual averages NW Scotland 2040-2069')
plt.title('Scatter plot of Significant Wave Height')
plt.show()

--

What I would like to do is display the R squared value next to the line of best fits that I have made.

Does anyone know how to do this with matplotlib?

Thanks,

Jamie
 
J

Jason Swails

​​



wrote:
Click to expand...
I have made a plot using the following code:

python2.7
import netCDF4
import matplotlib.pyplot as plt
import numpy as np


swh_Q0_con_sw=netCDF4.Dataset('/data/cr1/jmitchel/Q0/swh/controlperiod/south_west/swhcontrol_swest_annavg1D.nc','r')
hs_Q0_con_sw=swh_Q0_con_sw.variables['hs'][:]

swh_Q3_con_sw=netCDF4.Dataset('/data/cr1/jmitchel/Q3/swh/controlperiod/south_west/swhcontrol_swest_annavg1D.nc','r')
hs_Q3_con_sw=swh_Q3_con_sw.variables['hs'][:]

swh_Q4_con_sw=netCDF4.Dataset('/data/cr1/jmitchel/Q4/swh/controlperiod/south_west/swhcontrol_swest_annavg1D.nc','r')
hs_Q4_con_sw=swh_Q4_con_sw.variables['hs'][:]

swh_Q14_con_sw=netCDF4.Dataset('/data/cr1/jmitchel/Q14/swh/controlperiod/south_west/swhcontrol_swest_annavg1D.nc','r')
hs_Q14_con_sw=swh_Q14_con_sw.variables['hs'][:]

swh_Q16_con_sw=netCDF4.Dataset('/data/cr1/jmitchel/Q16/swh/controlperiod/south_west/swhcontrol_swest_annavg1D.nc','r')
hs_Q16_con_sw=swh_Q16_con_sw.variables['hs'][:]

swh_Q0_fut_sw=netCDF4.Dataset('/data/cr1/jmitchel/Q0/swh/2050s/south_west/swh2050s_swest_annavg1D.nc','r')
hs_Q0_fut_sw=swh_Q0_fut_sw.variables['hs'][:]

swh_Q3_fut_sw=netCDF4.Dataset('/data/cr1/jmitchel/Q3/swh/2050s/south_west/swh2050s_swest_annavg1D.nc','r')
hs_Q3_fut_sw=swh_Q3_fut_sw.variables['hs'][:]

swh_Q4_fut_sw=netCDF4.Dataset('/data/cr1/jmitchel/Q4/swh/2050s/south_west/swh2050s_swest_annavg1D.nc','r')
hs_Q4_fut_sw=swh_Q4_fut_sw.variables['hs'][:]

swh_Q14_fut_sw=netCDF4.Dataset('/data/cr1/jmitchel/Q14/swh/2050s/south_west/swh2050s_swest_annavg1D.nc','r')
hs_Q14_fut_sw=swh_Q14_fut_sw.variables['hs'][:]

swh_Q16_fut_sw=netCDF4.Dataset('/data/cr1/jmitchel/Q16/swh/2050s/south_west/swh2050s_swest_annavg1D.nc','r')
hs_Q16_fut_sw=swh_Q16_fut_sw.variables['hs'][:]

fit_Q0_sw=np.polyfit(hs_Q0_con_sw,hs_Q0_fut_sw,1)
fit_fn_Q0_sw=np.poly1d(fit_Q0_sw)

plt.plot(hs_Q0_con_sw,hs_Q0_fut_sw,'g.')
plt.plot(hs_Q0_con_sw,fit_fn_Q0_sw(hs_Q0_con_sw),'g',label='Q0 no pert')

fit_Q3_sw=np.polyfit(hs_Q3_con_sw,hs_Q3_fut_sw,1)
fit_fn_Q3_sw=np.poly1d(fit_Q3_sw)

plt.plot(hs_Q3_con_sw,hs_Q3_fut_sw,'b.')
plt.plot(hs_Q3_con_sw,fit_fn_Q3_sw(hs_Q3_con_sw),'b',label='Q3 low sens')

fit_Q4_sw=np.polyfit(hs_Q4_con_sw,hs_Q4_fut_sw,1)
fit_fn_Q4_sw=np.poly1d(fit_Q4_sw)

plt.plot(hs_Q4_con_sw,hs_Q4_fut_sw,'y.')
plt.plot(hs_Q4_con_sw,fit_fn_Q4_sw(hs_Q4_con_sw),'y',label='Q4 low sens')

fit_Q14_sw=np.polyfit(hs_Q14_con_sw,hs_Q14_fut_sw,1)
fit_fn_Q14_sw=np.poly1d(fit_Q14_sw)

plt.plot(hs_Q14_con_sw,hs_Q14_fut_sw,'r.')
plt.plot(hs_Q14_con_sw,fit_fn_Q14_sw(hs_Q14_con_sw),'r',label='Q14 high
sens')

fit_Q16_sw=np.polyfit(hs_Q16_con_sw,hs_Q16_fut_sw,1)
fit_fn_Q16_sw=np.poly1d(fit_Q16_sw)

plt.plot(hs_Q16_con_sw,hs_Q16_fut_sw,'c.')
plt.plot(hs_Q16_con_sw,fit_fn_Q16_sw(hs_Q16_con_sw),'c',label='Q16 high
sens')

plt.legend(loc='best')
plt.xlabel('Significant Wave Height annual averages NW Scotland 1981-2010')
plt.ylabel('Significant Wave Height annual averages NW Scotland 2040-2069')
plt.title('Scatter plot of Significant Wave Height')
plt.show()

--

What I would like to do is display the R squared value next to the line of
best fits that I have made.

Does anyone know how to do this with matplotlib?
Click to expand...

​You can add plain text or annotations with arrows using any of theAPI
functions described here:
http://matplotlib.org/1.3.1/users/text_intro.html(information
specifically regarding the text call is here:
http://matplotlib.org/1.3.1/api/pyplot_api.html#matplotlib.pyplot.text)

You can also use LaTeX typesetting here, so you can make the text something
like r'$R^2$' to display R^2 with "nice" typesetting. (I typically use raw
strings for matplotlib text strings with LaTeX formulas in them since LaTeX
makes extensive use of the \ character.)

The onus is on you, the programmer, to determine _where_ on the plot you
want the text to appear. Since you know what you are plotting, you can
write a quick helper function that will compute the optimal (to you)
location for the label to occur based on where things are drawn on the
canvas. There is a _lot_ of flexibility here so you should be able to get
your text looking exactly how (and where) you want it.

Hope this helps,
Jason
 
J

Jamie Mitchell

I have made a plot using the following code:



python2.7

import netCDF4

import matplotlib.pyplot as plt

import numpy as np



swh_Q0_con_sw=netCDF4.Dataset('/data/cr1/jmitchel/Q0/swh/controlperiod/south_west/swhcontrol_swest_annavg1D.nc','r')

hs_Q0_con_sw=swh_Q0_con_sw.variables['hs'][:]

swh_Q3_con_sw=netCDF4.Dataset('/data/cr1/jmitchel/Q3/swh/controlperiod/south_west/swhcontrol_swest_annavg1D.nc','r')

hs_Q3_con_sw=swh_Q3_con_sw.variables['hs'][:]

swh_Q4_con_sw=netCDF4.Dataset('/data/cr1/jmitchel/Q4/swh/controlperiod/south_west/swhcontrol_swest_annavg1D.nc','r')

hs_Q4_con_sw=swh_Q4_con_sw.variables['hs'][:]

swh_Q14_con_sw=netCDF4.Dataset('/data/cr1/jmitchel/Q14/swh/controlperiod/south_west/swhcontrol_swest_annavg1D.nc','r')

hs_Q14_con_sw=swh_Q14_con_sw.variables['hs'][:]

swh_Q16_con_sw=netCDF4.Dataset('/data/cr1/jmitchel/Q16/swh/controlperiod/south_west/swhcontrol_swest_annavg1D.nc','r')

hs_Q16_con_sw=swh_Q16_con_sw.variables['hs'][:]

swh_Q0_fut_sw=netCDF4.Dataset('/data/cr1/jmitchel/Q0/swh/2050s/south_west/swh2050s_swest_annavg1D.nc','r')

hs_Q0_fut_sw=swh_Q0_fut_sw.variables['hs'][:]

swh_Q3_fut_sw=netCDF4.Dataset('/data/cr1/jmitchel/Q3/swh/2050s/south_west/swh2050s_swest_annavg1D.nc','r')

hs_Q3_fut_sw=swh_Q3_fut_sw.variables['hs'][:]

swh_Q4_fut_sw=netCDF4.Dataset('/data/cr1/jmitchel/Q4/swh/2050s/south_west/swh2050s_swest_annavg1D.nc','r')

hs_Q4_fut_sw=swh_Q4_fut_sw.variables['hs'][:]

swh_Q14_fut_sw=netCDF4.Dataset('/data/cr1/jmitchel/Q14/swh/2050s/south_west/swh2050s_swest_annavg1D.nc','r')

hs_Q14_fut_sw=swh_Q14_fut_sw.variables['hs'][:]

swh_Q16_fut_sw=netCDF4.Dataset('/data/cr1/jmitchel/Q16/swh/2050s/south_west/swh2050s_swest_annavg1D.nc','r')

hs_Q16_fut_sw=swh_Q16_fut_sw.variables['hs'][:]



fit_Q0_sw=np.polyfit(hs_Q0_con_sw,hs_Q0_fut_sw,1)

fit_fn_Q0_sw=np.poly1d(fit_Q0_sw)



plt.plot(hs_Q0_con_sw,hs_Q0_fut_sw,'g.')

plt.plot(hs_Q0_con_sw,fit_fn_Q0_sw(hs_Q0_con_sw),'g',label='Q0 no pert')



fit_Q3_sw=np.polyfit(hs_Q3_con_sw,hs_Q3_fut_sw,1)

fit_fn_Q3_sw=np.poly1d(fit_Q3_sw)



plt.plot(hs_Q3_con_sw,hs_Q3_fut_sw,'b.')

plt.plot(hs_Q3_con_sw,fit_fn_Q3_sw(hs_Q3_con_sw),'b',label='Q3 low sens')



fit_Q4_sw=np.polyfit(hs_Q4_con_sw,hs_Q4_fut_sw,1)

fit_fn_Q4_sw=np.poly1d(fit_Q4_sw)



plt.plot(hs_Q4_con_sw,hs_Q4_fut_sw,'y.')

plt.plot(hs_Q4_con_sw,fit_fn_Q4_sw(hs_Q4_con_sw),'y',label='Q4 low sens')



fit_Q14_sw=np.polyfit(hs_Q14_con_sw,hs_Q14_fut_sw,1)

fit_fn_Q14_sw=np.poly1d(fit_Q14_sw)



plt.plot(hs_Q14_con_sw,hs_Q14_fut_sw,'r.')

plt.plot(hs_Q14_con_sw,fit_fn_Q14_sw(hs_Q14_con_sw),'r',label='Q14 highsens')



fit_Q16_sw=np.polyfit(hs_Q16_con_sw,hs_Q16_fut_sw,1)

fit_fn_Q16_sw=np.poly1d(fit_Q16_sw)



plt.plot(hs_Q16_con_sw,hs_Q16_fut_sw,'c.')

plt.plot(hs_Q16_con_sw,fit_fn_Q16_sw(hs_Q16_con_sw),'c',label='Q16 highsens')



plt.legend(loc='best')

plt.xlabel('Significant Wave Height annual averages NW Scotland 1981-2010')

plt.ylabel('Significant Wave Height annual averages NW Scotland 2040-2069')

plt.title('Scatter plot of Significant Wave Height')

plt.show()



--



What I would like to do is display the R squared value next to the line of best fits that I have made.



Does anyone know how to do this with matplotlib?



You can add plain text or annotations with arrows using any of the API functions described here: http://matplotlib.org/1.3.1/users/text_intro.html(information specifically regarding the text call is here: http://matplotlib.org/1.3.1/api/pyplot_api.html#matplotlib.pyplot.text)



You can also use LaTeX typesetting here, so you can make the text something like r'$R^2$' to display R^2 with "nice" typesetting. (I typically use raw strings for matplotlib text strings with LaTeX formulas in them since LaTeX makes extensive use of the \ character.)



The onus is on you, the programmer, to determine _where_ on the plot you want the text to appear.  Since you know what you are plotting, you can write a quick helper function that will compute the optimal (to you) location for the label to occur based on where things are drawn on the canvas.  There is a _lot_ of flexibility here so you should be able to get your textlooking exactly how (and where) you want it.



Hope this helps,
Jason


--

Jason M. Swails
BioMaPS,
Rutgers University
Postdoctoral Researcher
Click to expand...

Hi Jason,

Thank you for your swift response - you solved my problem!

Sorry I took a while to get back to you.

Thanks again,

Jamie
 

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