| Kind | Count | What they do |
|---|---|---|
| Verbs | 16 | Steps in a pipeline. Every one is an imperative English verb |
| Aggregations | 11 | Collapse a group to one value |
| Windows | 7 | Answer for every row by looking at the other rows |
| Scalar functions | 20 | Answer for one row from that row |
| Grammar words | 30 | The small words that join the rest together |
Appendix B — Every word in the grammar
The whole vocabulary, on one page. If you are deciding whether to learn this, read the list and see how long it takes. That is the argument, and it is shorter than the argument for it.
Nothing here is typed by hand. The engine is asked what words it has when this page is built, so the list cannot describe a word that was removed or miss one that was added.
B.1 The verbs
A pipeline is a table, then then, then one of these, repeated.
`keep` · `pick` · `add` · `summarize` · `sort` · `take` · `take_last` · `join` · `add_rows` · `drop_duplicates` · `rename` · `drop_missing` · `fill_missing` · `add_combinations` · `lengthen` · `widen`keep and pick are the two that choose: rows and columns. add and summarize are the two that make a column: one per row, and one per group. sort and take order and cut, and take_last cuts from the other end. Everything after those seven is a second table, a missing value, a change of shape, or the housekeeping pair that renames a column and drops repeated rows.
B.2 The aggregations
These go inside summarize, and inside add when it carries a by.
`total` · `average` · `median` · `smallest` · `largest` · `standard_deviation` · `first` · `last` · `unique_count` · `row_count` · `join_rows`B.3 The windows
These answer once per row by looking along the other rows. Several of them require a sort in front, because they mean nothing until something has said in what order.
`rank` · `row_number` · `running_total` · `previous` · `following` · `rolling` · `latest`B.4 The scalar functions
One row in, one value out. These go anywhere a value goes.
`first_present` · `join_text` · `lower` · `upper` · `to_number` · `to_text` · `to_date` · `round_below` · `round_above` · `trim` · `replace_text` · `split_text` · `characters` · `between` · `remainder` · `year` · `month` · `day` · `weekday` · `hour`B.5 The grammar words
Not verbs and not functions. These are the joints: they say how the words on either side of them are related.
`then` · `where` · `as` · `by` · `all_but` · `descending` · `in` · `is` · `not` · `and` · `or` · `yes` · `no` · `missing` · `unmatched` · `starts` · `ends` · `contains` · `name` · `value` · `kind` · `giving` · `when` · `otherwise` · `look_up` · `matching` · `any` · `every` · `with` · `ties`B.6 Where each word is first used
Each verb and function below links to the page whose running example uses it first, in the book’s own order. The table is worked out from the chapters when the page is built, the same way the lists above come from the engine. A moved example moves its link, and a word no chapter runs cannot ship at all, because a build check refuses the book first.
| Word | First running example | |
|---|---|---|
| keep | keep |
Your first pipeline |
| pick | pick |
Choosing columns |
| add | add |
Your first pipeline |
| summarize | summarize |
Your first pipeline |
| sort | sort |
Your first pipeline |
| take | take |
Adding a column |
| take_last | take_last |
Sorting and taking |
| join | join |
Missing values |
| add_rows | add_rows |
Adding rows |
| drop_duplicates | drop_duplicates |
Renaming and repeats |
| rename | rename |
Renaming and repeats |
| drop_missing | drop_missing |
Missing values |
| fill_missing | fill_missing |
The rows that are not there |
| add_combinations | add_combinations |
The rows that are not there |
| lengthen | lengthen |
Columns into rows |
| widen | widen |
Rows into columns |
| total | total |
Your first pipeline |
| average | average |
Summarizing by group |
| median | median |
Summarizing by group |
| smallest | smallest |
Summarizing by group |
| largest | largest |
Summarizing by group |
| standard_deviation | standard_deviation |
Summarizing by group |
| first | first |
Summarizing by group |
| last | last |
Summarizing by group |
| unique_count | unique_count |
Summarizing by group |
| row_count | row_count |
Your first pipeline |
| join_rows | join_rows |
Tidying text |
| rank | rank |
The words that repeat |
| row_number | row_number |
Adding a column |
| first_present | first_present |
Missing values |
| join_text | join_text |
Tidying text |
| lower | lower |
Tidying text |
| upper | upper |
Tidying text |
| to_number | to_number |
Saying what something is |
| to_text | to_text |
Saying what something is |
| to_date | to_date |
Dates |
| round_below | round_below |
Adding a column |
| round_above | round_above |
Adding a column |
| trim | trim |
Tidying text |
| replace_text | replace_text |
Tidying text |
| split_text | split_text |
Tidying text |
| characters | characters |
Tidying text |
| between | between |
Saying what something is |
| remainder | remainder |
Adding a column |
| year | year |
Summarizing by group |
| month | month |
Dates |
| day | day |
Dates |
| weekday | weekday |
Dates |
| hour | hour |
Dates |
| running_total | running_total |
The total so far |
| previous | previous |
The total so far |
| following | following |
The total so far |
| rolling | rolling |
The total so far |
| latest | latest |
Missing values |
The grammar words are not in the table on purpose. in, is, not and their siblings are also words the host languages use, so a scan would confidently attribute the wrong page. They are everywhere above instead.
B.7 Every word answers for itself
You do not have to come back here. Each word above has a page where you are already sitting, and every one of them carries an example you can paste.
?keep
?add_combinationshelp(god.keep)
help(god.add_combinations)The two show the same example in the two spellings, down to the same table and the same numbers. That is this book’s claim stated one word at a time. They are run rather than written. The R suite executes the example on every help page, and the Python suite executes every one in every docstring. A page that no longer matches the engine fails a build rather than misleading the reader who went looking.
One difference between those pages and these can surprise you. This book tells Python to print a whole number without its decimal point, so that the tabs of an example agree. Nothing has told your own session that, and a total of whole numbers arrives there as 250.0 rather than 250. The Python help pages show 250.0, because that is what you will see.
B.8 That is all of it
There is no second list, no set of helpers, and no dialect that adds a few more on a cluster. A word that is not above is not in the grammar. Asking for one gets a refusal that lists the words it could have been, and names the nearest when the spelling is close.