Adding line to scatter plot using python's matplotlib

Question

I am using python\'s matplotlib and want to create a matplotlib.scatter() with additional line. The line should proceed from the lower left corner to the upper righ

Answer 1

Besides unutbu's answer one other option is to get the limits of the axis after you ploted the data and to use them to add the line. After this you will still need to change back the axis limits as they would change with the addition of the line:

# Scatter Plot
x = data_calc_hourly.temp
y =  data_obs_hourly.temp

lineStart = data_calc_hourly.temp.min() 
lineEnd = data_calc_hourly.temp.max()  

plt.figure()
plt.scatter(x, y, color = 'k', alpha=0.5)
y_lim = plt.ylim()
x_lim = plt.xlim()
plt.plot(x_lim, y_lim, 'k-', color = 'r')
plt.ylim(y_lim)
plt.xlim(x_lim)
plt.show()