The closing of the L line and NYC demographics

We will need the following datasets for this exercise:

1. Create a map

  • Click on NEW MAP.
  • Click on CONNECT DATASET.
  • Drag and drop subway_nycstations_l.gpkg.
  • Click on CONNECT DATASET.
  • Click on Don't show me this again to avoid modals.
  • You can rename the map title as "The L line and demographics" by double-clicking on it.

map

2. Layers

  • Add new layers:
  • Click on ADD.
  • Clik on UPLOAD.
  • Find nyc_subway_lines.gpkg on your computre and click on UPLOAD DATASET.
  • Click on ADD LAYER.

  • Reapeat the same for nyc_block_group_census.csv

  • Now, by moving the layers using drag and drop we can change the order in which the layers are being displayed. We move subway_nycstations_l to the top and nyc_subway_lines in the second position. The layer nyc_block_group_census woudl stay at the bottom of the map.

layers_ordered

  • Click on one of the layers to show its components:
  • DATA tab: an overview of your table schema, from here you can also add widgets. If you want to have a look at your dataset, click the Data View icon, located on the bottom right of Builder when a map layer is selected.

table

Take a look at the letter and number the layers card has (A, B or C). This would be very useful for adding widgets and analysis. Depending on the order in which you added your data, your layer letters could be different than the screenshots. In this example, subway stations were layer A, subway lines layer B, and block groups layer C.

layer

3. Analysis

3.1 Filter by column value

  • Go to the edit pane.
  • Click layer nyc_subway_lines and then select the Analysis tab. Finally, click on the ADD ANALYSIS button in order to add the analysis.
  • Select Filter by column value analysis.
  • Click on ADD ANALYSIS.
  • Set the parameters as follows:
  • TARGET COLUMN: route_id.
  • VALUE: L.
  • RESULTS: show.
  • Now click on APPLY to see the result of the filtering. This is the L subway line.

filter

3.2 Create Travel/Distance buffer analysis

  • We will apply this analysis to the layer subway_nycstations_l. Go back to the LAYERS pane in Builder's interface and click on 0 ANALYSES under subway_nycstations_l. Click on ANALYSIS, then on ADD ANALYSIS.
  • Select the Create Travel/Distance buffer analysis. Click ADD ANALYSIS.
  • In the ANALYSIS tab of the layer, we have three sections:
  • Your workflow: Since this is the first analysis we're adding to the subway_nycstations_l layer, node A, the analysis layer will be named node A1.
  • Create areas of influence:
    • BASE LAYER: Should be the layer subway_nycstations_l, node A (A0).
    • TYPE: Distance
    • UNIT: mi
    • RADIUS: 1
    • TRACKS: 1
    • BOUNDARIES: Intact
  • After clicking APPLY, we should see this result: an area of influence of 1 mile around each subway station.

aoi

3.3 Intersect and Aggregate analysis

  • Go to the edit pane.
  • Click layer nyc_block_group_census and then select the Analysis tab. Finally, click on the ADD ANALYSIS button in order to add the analysis.
  • Select Intersect and aggregate analysis.
  • In the ANALYIS tab of the layer, we have three sections:
  • Your workflow: Since this is the first analysis we're adding to the nyc_block_group_census layer, node C, this analysis layer will be named node C1.
  • Aggregate intersection:
    • Base Layer: By default the base layer would be nyc_block_group_census.
    • Target Layer: select the result layer of the Area of Influence analysis A1
  • After clicking APPLY, we should see this result:

intersect

3.4 Extract source node and reorder layers

Since we used our subway station layer as the input for the buffers analysis, the data appears as polygons. We want the buffers to be underneath the subway lines, and to extract the original subway station points for display.

  • From the subway_stations_l layer, drag out the buffers sublayer and place it under the nyc_subway_lines layer
  • This will create a new layer D, and you will see the subway stations drawn on top of the AOI and block group layers

new_layer

4. Styling

  • Go to the edit pane, click on the AOI layer D and select the STYLE tab. Set the Fill color to a grey with high opacity, and make the stroke grey also.

  • Go to the edit pane, click on the nyc_block_group_census layer D and select the STYLE tab. Set the Fill color to a grey that blends with the basemap layer.

style

5. Widgets

  • Go to the edit pane and click on the widgets tab.
  • Click on ADD WIDGET button.
  • Under the CATEGORY tab, click on the check box of variables stop_name and ethnic_1st
  • Under the 'HISTOGRAM' tab, click on the check box of variables median_household_income and median_age
  • Under the 'FORMULA' tab, click on the check box of variable total_pop.
  • Click on CONTINUE


widgets

5.1 Explore and style data with Widgets

  • Click on the tear drop icon inside each widget to see the Auto-style feature.
  • Filter the data by interacting with the category and histogram widgets.

widget_filter

5.2 Customize widgets

  • Reorder widgets: From WIDGET tab, drag and drop them into your preferred order.
  • Rename widgets: From WIDGET tab, rename each widget by clicking on its three blue dots and selecting the option to Rename.
  • Formula widget calculation:
  • By default, the formula widget is calculating the average population. However, we want to see the sum of the total population within our map view.
  • Click on the three blue dots in the Total Population widget and select the option to 'Edit'
  • In the OPERATION parameter, select sum.

custom_widget

6. Publish

  • Click on SHARE.
  • Set the map's privacy to LINK or PUBLIC.
  • Click on PUBLISH.
  • Now you can share the map:
  • Link: https://team.carto.com/u/builder-demo/builder/144826d6-0982-11e7-bdeb-0e233c30368f/embed
  • iframe: <iframe width="100%" height="520" frameborder="0" src="https://team.carto.com/u/builder-demo/builder/144826d6-0982-11e7-bdeb-0e233c30368f/embed" allowfullscreen webkitallowfullscreen mozallowfullscreen oallowfullscreen msallowfullscreen></iframe>

Remember to update your map every time you make a change. To see those changes refresh your embed, or the web page where your map is hosted.