Colouring candidates

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Using colours to detect patterns

It can be helpful to colour all the candidates for a certain symbol, say all the 5's, or to mark groups of cells using colours. The program has options for both of these techniques.

Colouring candidates

Some types of pattern can be spotted by colouring all occurrences of selected symbols. The File menu has an option "Colour/uncolour candidates" for this purpose. Selection of the option produces a cascading menu of the symbols 1-9 and the user drags down to make a choice.

SourGumdrop: using candidate colouring to spot patterns
Figure 1: using candidate colouring to spot patterns. Here, by colouring the 3's the user has spotted a jellyfish.


All candidates of the selected symbol will be set to the current colour. If the user later selects the same symbol from this menu its colour will be switched off and all the candidates for this symbol will have their colour status toggled. That is, those that are coloured will be uncoloured and those that are uncoloured will be coloured. How can some be coloured and some not? Well, the middle mouse button can be used to toggle the colour status of individual buttons (see below). At present there are 5 arbitrary colours available, so up to 5 symbols could each be given a different colour at any time.

As mentioned it is also possible to colour/uncolour individual symbols using the middle mouse button. Clicking the middle mouse button on the button for a symbol will toggle its colour setting: if it was uncoloured it will be coloured, if it was coloured it will be uncoloured. That all colouring operations are toggles means that if you have coloured, say an individual "1" symbol, and then select to colour all "1"'s, the individually coloured button will be switched off, and vice versa.

Undo will remove all colouring.

The swordfish discovered in Figure 1. is made visible in Figure 2. Here the user has also coloured the cells and a hint request has coloured the candidates.

SourGumdrop: using candidate colouring to spot patterns: jellyfish
Figure 2: using candidate and cell colouring to spot patterns. Here, by colouring the 3's the user has spotted a jellyfish and the hint scheme has confirmed it.


Set candidate colour

The candidate colour is set by a File menu option "Set candidate colour" which produces a cascading menu of colours from which the user drags down to make a selection.

SourGumdrop: selecting the symbol colour
Figure 2. Selecting the symbol colour.

The selected colour will then be used in all "Colour candidates" choices until the user changes the colour through this option.