I would like to draw a scatter plot about the relationship between house prices and geographic coordinates using a colormap.

```
from mpl_toolkits.basemap import Basemap
lats = df['latitude'].as_matrix()
lons = df['longitude'].as_matrix()
zoom_scale = 0
bbox = [np.min(lats)-zoom_scale,np.max(lats)+zoom_scale,\
np.min(lons)-zoom_scale,np.max(lons)+zoom_scale]
plt.figure()
m = Basemap(projection='merc',llcrnrlat=bbox[0],urcrnrlat=bbox[1],\
llcrnrlon=bbox[2],urcrnrlon=bbox[3],resolution='i')
m.drawcoastlines()
m.drawrivers()
x,y = m(lons,lats)
cm = plt.cm.get_cmap('coolwarm')
plot = m.scatter(x,y,'o',c = df['price'],cmap=cm)
plt.colorbar(plot)
plt.title("House Price with Geographic Coordinate")
plt.show()
```

The console gives a TypeError:

TypeError Traceback (most recent call last) in

```
28 x,y = m(lons,lats)
29 cm = plt.cm.get_cmap('coolwarm')
---> 30 plot = m.scatter(x,y,'o',c = df['price'],cmap=cm)
31 plt.colorbar(plot)
32 plt.title("House Price with Geographic Coordinate")
....
/anaconda3/lib/python3.7/site-packages/matplotlib/collections.py in set_sizes(self, sizes, dpi)
872 self._sizes = np.asarray(sizes)
873 self._transforms = np.zeros((len(self._sizes), 3, 3))
--> 874 scale = np.sqrt(self._sizes) * dpi / 72.0 * self._factor
875 self._transforms[:, 0, 0] = scale
876 self._transforms[:, 1, 1] = scale
```

TypeError: ufunc 'sqrt' not supported for the input types, and the inputs could not be safely coerced to any supported types according to the casting rule ''safe''

How can I solve this? Best regards