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Redundant Special Variables header #27

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Redundant Special Variables header #27

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5 changes: 1 addition & 4 deletions Advanced_data_manipulation.Rmd
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Expand Up @@ -357,9 +357,6 @@ A ` list` containing a length 1 vector for each item in `by`.

### `.N`


## Special variables

An integer, length 1, containing the number of rows in `.SD`.

### `.I`
Expand Down Expand Up @@ -985,4 +982,4 @@ hai %>% group_by(SUBJECT_ACCESSION, STUDY_TIME_COLLECTED) %>% summarize(hai_mean
- Use `data.table` for your day-to-day operations
- When you have many tables and a complex schema, use `sqlite`.

**Note:** There many other R packages for "big data" such the `bigmemory` suite, `biglm`, `ff`, `RNetcdf`, `rhdf5`, etc.
**Note:** There many other R packages for "big data" such the `bigmemory` suite, `biglm`, `ff`, `RNetcdf`, `rhdf5`, etc.