Heat Maps: colour areas by their values
Turn a column of figures into a map that is easy to compare. A light-to-dark colour range can show lower and higher sales, customer counts or population totals. These heat maps colour the boundary shapes themselves; they do not create a blurred cloud of points.
Choose your figures
My postcode datasets opens your existing data library. Upload a postcode CSV or use a dataset already in your account, then choose Use on this map. Back in Heat Maps, select the figure to colour by. More detailed postcode totals are combined for the area or district map you are using.
Use a CSV for this map
Upload a CSV for this map works with the names of its boundary shapes, including county maps. Download this map’s area names gives you a ready-made list: add your values and save it as CSV. Drop the file into the box, check the area-name and values columns, and give the figures a name. The preview shows matches, repeated names and unmatched rows before you accept it. Repeated names are added together; empty values stay as No data. Correct any non-numerical entries before continuing. These figures stay with this saved map rather than being added to your account’s postcode dataset library. For Excel workbooks, use Save As CSV first.
Choose the colours and number of shades
Pick a colour strip and choose between three and nine shades. Blues, Greens and Teal are useful for low-to-high values. Heat runs from pale yellow towards red. Reverse the colours swaps which end represents the larger figures. A dataset with few distinct values may need fewer shades.
Read the preview before changing your map
The preview shows the number range and area count for each colour. Changing these controls does not recolour the map yet. Areas with missing figures are listed separately and become grey No data areas; a genuine zero is included in the numerical ranges.
Create the heat map
Create heat map applies those colours and adds editable zones to the normal legend. If the map already has coloured territories, a warning explains that their assignments will change. Choose Cancel if you want to keep them. Undo restores the previous colours, assignments and legend.
Keep your original map
For an already saved map, Create in a saved copy lets you give the new version its own name. The original is kept as it was and you continue editing the copy. Save an unsaved map once first if you want to keep both versions.
Change how values are grouped
More options offers similar numbers of areas per shade (quantiles), equal-sized number ranges, natural gaps in the values, or geometric intervals. Geometric intervals need every value to be above zero. Quantiles are a useful starting point; equal ranges make numerical comparisons more direct.
Make the legend readable
Choose normal numbers, pounds or percentages and the number of decimal places. The legend heading uses the dataset’s figure name unless you supply one. Only use percentage formatting for figures already calculated for the map areas: adding percentages from smaller places does not give a valid percentage.
Edit and save the result
The generated colours and labels are ordinary legend zones. Change their names or colours, or click on the map to adjust their assigned areas. Saving keeps the colours and the dataset version used to make them. Reopening does not automatically recolour the map when newer data is uploaded.