Punctuation graphs were described by Perlman and Erickson (1983). They are an interesting way to look at the structure of your writing and may be a useful way to visualise problems.
The graphs are made by putting each sentence in a paragraph on a new line, then replacing each word by an underscore, but leaving all punctuation in place. Here is an example of what you get.
The length of the lines give a visual indication of the length of sentences and the number and type of punctuation marks gives a visual indication of the complexity of the sentences. You can also see how many sentences there are in a paragraph.
This tool may help you spot problems, like lots of overly long sentences, lack of variation in sentence length, paragraphs that are too long and paragraphs that are too short. In the example above you can see that the second sentence is quite long. You should have a look to see if the sentence is so long that it is difficult for readers to follow. In the example below you can see that all sentences in the paragraph are relatively short. This writing is likely to feel quite choppy to readers.
Its pretty easy to produce a punctuation graph. Copy and paste a section of your text into a new document. Use the search and replace tool to make the changes. I started with putting each sentence on a new line by replacing full stops with a full stop and paragraph mark. Then I replaced words with 10 letters with an underscore using the any letter wildcard. Then I did 9 letters, then 8 letters, then 7 letters and so on until all the words were replaced with underscores. Then I replaced each underscore that was followed by a space with an underscore with no space, to get continuous lines—but you might prefer to leave the underscores separated as it may help you see how many words you have in a sentence.
Perlman G and Erickson TD (1983) Graphical abstractions of technical documents. Visible Language, 17(4): 380-389.