Displaying data filtered from a list

MIT App Inventor Help
1

ListLernin.aia (8.7 KB)

When I click the button, lat and lon are set as variables. I want to filter the list ‘global Master’ to show which location is represented by the ‘global lat/lon’ variables.

With the included csv file, it should return list item 137 - which is the location of my work.

Nothing populates though.

I have not found a search subject that tries to do the same - if there is, thank you for showing me where :slight_smile:!

blocks
blocks1833×601 70.6 KB

2

Here is a sample from Geofences.csv:

stop_id,stop_name,stop_desc,stop_lat,stop_lon,lat_north,lat_south,lon_west,lon_east
FT2,Quachita Tr. & Seneca Tr.,,38.22415,-84.82103,38.22440,38.22390,-84.82128,-84.82078
FT3,Quachita Tr. & Steadmantown Ln,,38.22321,-84.81965,38.22346,38.22296,-84.81990,-84.81940
FT5,Steadmantown Ln. & Powhatan Tr.,,38.22089,-84.81978,38.22114,38.22064,-84.82003,-84.81953
FT9,Steadmantown Ln. & Lakeview Ct.,,38.21636,-84.81868,38.21661,38.21611,-84.81893,-84.81843
FT11,United States Post Office,,38.21603,-84.86510,38.21628,38.21578,-84.86535,-84.86485
FT12,Hall St.,,38.21662,-84.86003,38.21687,38.21637,-84.86028,-84.85978
FT13,Schenkel Ln.,,38.21616,-84.84079,38.21641,38.21591,-84.84104,-84.84054
FT15,Compton Dr.,,38.21335,-84.86418,38.21360,38.21310,-84.86443,-84.86393
FT16,Letcher Ave & Swigert Ave.,,38.21433,-84.85869,38.21458,38.21408,-84.85894,-84.85844
FT17,Schenkel Ln. & Park Hills Apartments,,38.21396,-84.84374,38.21421,38.21371,-84.84399,-84.84349
FT18,Steadmantown Ln. & Park Ave.,,38.21383,-84.81925,38.21408,38.21358,-84.81950,-84.81900
3

These blocks should return your office label (you should be able to drag these into your project)

blocks (4)
blocks (4)717×321 45.8 KB

1 Like
4

For fractional values, equality is rare.

You might have to settle for a looser test, involving some small allowable error value,
and test if abs(x1-x2) < error value and
abs(y1-y2) < error value to test if (x1,y2) matches (x2,y2).

1 Like
5

Looser values I can live with. Definitely going to see if that allows for more consistency in value returns.

6

Ok, thank you. So my error was using ‘get global Master’ when I should have been using the ‘get item’ from the ‘for each’ block?

Appreciate your answer.

7

You had more errors than that.

06bc2f8cc34b989aef4c15efc39008b40e03eff1_2_690x226
06bc2f8cc34b989aef4c15efc39008b40e03eff1_2_690x2261380×452 199 KB

Half of the work of coding is reading, both what others write and what you write.

8

Understood. I was misunderstanding the purpose of the list - assuming that it was how I identified a row and a column in that row.

I did not know I could put the actual column name in the index, so I could use a text block and make it “stop_id” if I wanted.

That got me running and I have made progress. Thanks for the clarification on the column/row and ‘item’ differentiation.