Reference Request – On the model of an injective holomorphic map

Thank you for giving MathOverflow an answer!

  • Please be sure too answer the question, Provide details and share your research!

But avoid

  • Ask for help, clarification or answering other questions.
  • Make statements based on opinions; Cover them with references or personal experience.

Use MathJax to format equations. Mathjax reference.

For more information, see our tips for writing great answers.

2d – Where should I start? Simple website with map and real-time tagged player locations

I am looking for ways to create a simple 2D map on a web page (eg, the layout of a building) and to display "data points" (eg, user locations) on the map using a colored icon or the like.

To achieve this goal, look for suggestions or examples of how others have achieved the same goal.

Like a site map of your building with a point where each user is currently located … nothing too complex.

Stream – Java for loop with map merge

Simple conversion of one type into another.

Is there a better way with streams:

                Map <String, Set> result = new HashMap <> ();
for (Pair Pair: result list) {
to adjust strSet = new HashSet <> ();
strSet.add (pair.getRight ());
result.merge (pair.getLeft (), strSet, new BiFunction <Set, To adjust, To adjust> () {
public set Apply (Set Electricity, set additionally) {
if (current == null) {
Return in addition;
current.addAll (additional);
Return power;
Return result;

GUI design – Are users actually using the zoom buttons on a map?

You are easily asking the wrong question. Anyone who has seen a usability test will tell you that when you add a button, at least some people will click on it.

The real question you ask yourself is whether people would struggle if the buttons were not there, and I would suggest that many people would do it, but I can not prove it without testing ( and nobody else can).

The reason I might be worried is that the gestures zoom controls (double-tap, press-zoom, etc.) are not very noticeable. There is nothing like a flat card that zooms naturally. So it's plausible that someone does not realize that he can zoom in if he does not see a specific control for it.

Buttons are also much more accessible than gestures. People can press buttons with a finger, with certain motor difficulties, with low-quality touchscreens, with technical aids (on the internet, you can call a keyboard key, and in a car you can often find functions or steering wheel buttons with control units such as dials, but how do you call a "pinch" in the distance?).

The underlying problem with hiding the card is a reasonable problem. You may be able to hide and show the controls when the user taps the ad or leave them visible until the user invokes a zoom in some other way. Just make sure that you test whether your design raises any user-friendliness concerns.

Java – Google Maps API – Reading locations from files and displaying markers on the map

I work with Google Maps and want to read site objects into the map. I load them from a CSV file and create shelter objects for each location that I store in an ArrayList. To actually add them to the map, I go through this ArrayList and create tag objects with the data of each object. Each actually created marker object is also stored in another ArrayList, so that I can reference it later (show / hide on the map if desired). I feel like I am doing something wrong. I have given the relevant methods below.

private ArrayList shelter objects;
private ArrayList shelter markers;

// Generate the shelter objects from the CSV file and add them to the ArrayList.
private void generateShelterObjects ()
shelterObjects = new ArrayList <> ();

Log.i ("SHELTER_TEST", "METHOD generateShelterObjects () STARTED");

InputStream is = getResources (). OpenRawResource (R.raw.shelters_csv_file);
BufferedReader reader = new BufferedReader (
new InputStreamReader (is, Charset.forName ("UTF-8")));
String line = "";

To attempt {
while ((line = reader.readLine ())! = null) {
// Divide the line into different tokens (with the comma as separator).
string[] tokens = line.split (",");

String address = token[0];
double latitude = Double.parseDouble (token[1]);
double longitude = Double.parseDouble (token[2]);
int numberOfOccupants = Integer.parseInt (token[3]);

ShelterObject object = new ShelterObject (address, latitude, longitude, number of participants);
shelterObjects.add (object);


} catch (IOException e1) {
Log.e ("MapsActivity2", "Error" + line, e1);
e1.printStackTrace ();
Log.i ("SHELTER_TEST", "The size of the array after reading objects:" + shelterObjects.size ());

// traverses the ArrayList of Shelter objects and adds a tag to the map with data from that object. The markers are stored in another ArrayList so that they can be referenced later.
private void addShelterMarkersToMap ()
shelterMarkers = new ArrayList <> ();

for (ShelterObject obj: shelterObjects) {
LatLng latLng = new LatLng (obj.getLatitude (), obj.getLongitude ());
Marker marker = mMap.addMarker (new MarkerOptions ()
position (latLng)
.title (obj.getAddress ())
.snippet ("Antal platser:" + obj.getNumberOfOccupants ()));
shelterMarkers.add (marker);

Are the zoom buttons actually used on a map?

Are the + and – zoom buttons on a flyer card really necessary between the touchscreens and the scroll wheels? I would really like to remove them if there is no good reason to keep them there. Not only to save space, but above all to clear out, as many other buttons can use this space.

Javascript – if condition within the map function

How can I put an if condition on my function so that no undefined is returned?

Thats my job: (key => ({key, value: data)[key]}))

She returns this:

[ { key: 'a', value: 2 },
  { key: 'b', value: 2 },
  { key: 'c', value: 2 },
  { key: 'd', value: undefined },
  { key: 'e', value: undefined },
  { key: 'f', value: 2 } ]

I tried a few options, but to no avail.

One of my attempts: (key => (if (date[key]! = undefined) {{key, value: data[key](That