## Pick Locations Interactively

You can use Mapping Toolbox™ functions and GUIs to interact with maps, both in `mapview` and in figures created with `axesm`. This section describes two useful graphic input functions, `inputm` and `gcpmap`. The `inputm` function (analogous to the MATLAB® `ginput` function) allows you to get the latitude-longitude position of a mouse click. The `gcpmap` function (analogous to the MATLAB function `get(gca,'CurrentPoint'))` returns the current mouse position, also in latitude and longitude.

Explore `inputm` with the following commands, which display a map axes with its grid and then request three mouse clicks, the locations of which are stored as geographic coordinates in the variable `points`. Then the `plotm` function plots the points you clicked as red markers. The display you see depends on the points you select:

```axesm sinusoid framem on; gridm on points=inputm(3) ```
```points = -41.7177 -145.0293 7.9211 -0.5332 38.5492 149.2237```
`plotm(points,'r*')` ### Note

If you click outside the map frame, `inputm` returns a valid but incorrect latitude and longitude, even though the point you indicated is off the map.

One reason you might want to manually identify points on a map is to interactively explore how much distortion a map projection has at given locations. For example, you can feed the data acquired with `inputm` to the `distortcalc` function, which computes area and angular distortions at any location on a displayed map axes. If you do so using the `points` variable, the results of the previous three mouse clicks are as follows:

`[areascale,angledef] = distortcalc(points(1,1),points(1,2))`
```areascale = 1.0000 angledef = 85.9284```
`[areascale,angledef] = distortcalc(points(2,1),points(2,2))`
```areascale = 1.0000 angledef = 3.1143```
`[areascale,angledef] = distortcalc(points(3,1),points(3,2))`
```areascale = 1.0000 angledef = 76.0623```

This indicates that the current projection (sinusoidal) has the equal-area property, but exhibits variable angular distortion across the map, less near the equator and more near the poles. 