10.19 Subset of Rows Within Groups
20200814 The dplyr::slice() command understands
groups and so the indicies supplied will apply to each group. To
select, for example, the second row of each group, simply supply
2 as the argument. Notice the rows selected are all on the
second of the month.
ds %>%
group_by(location) %>%
slice(2)## # A tibble: 49 × 24
## # Groups: location [49]
## date location min_t…¹ max_t…² rainf…³ evapo…⁴ sunsh…⁵ wind_…⁶ wind_…⁷
## <date> <chr> <dbl> <dbl> <dbl> <dbl> <dbl> <ord> <dbl>
## 1 2008-07-02 Adelaide 12.7 15.8 0.8 1.4 7.8 SW 35
## 2 2008-12-02 Albany 14.7 21 0 5.4 9.1 W 39
## 3 2008-12-02 Albury 7.4 25.1 0 4.8 8.5 WNW 44
## 4 2008-12-02 AliceSpri… 21 39.1 1.2 9 12.2 NNW 41
## 5 2009-01-02 BadgerysC… 14.7 26.1 0 4.8 8.5 SE 46
## 6 2008-12-02 Ballarat 4.3 19.5 0.4 4.8 8.5 WNW 44
## 7 2008-12-02 Bendigo 6.2 23 0 8.8 8.5 W 48
## 8 2008-07-02 Brisbane 8.1 22.9 0 2 9.8 W 30
## 9 2008-12-02 Cairns 24.2 32.3 8.4 6.6 5.3 NE 35
## 10 2007-11-02 Canberra 14 26.9 3.6 4.4 9.7 ENE 39
## # … with 39 more rows, 15 more variables: wind_dir_9am <ord>,
## # wind_dir_3pm <ord>, wind_speed_9am <dbl>, wind_speed_3pm <dbl>,
## # humidity_9am <dbl>, humidity_3pm <dbl>, pressure_9am <dbl>,
## # pressure_3pm <dbl>, cloud_9am <dbl>, cloud_3pm <dbl>, temp_9am <dbl>,
## # temp_3pm <dbl>, rain_today <fct>, risk_mm <dbl>, rain_tomorrow <fct>, and
## # abbreviated variable names ¹min_temp, ²max_temp, ³rainfall, ⁴evaporation,
## # ⁵sunshine, ⁶wind_gust_dir, ⁷wind_gust_speedYour donation will support ongoing availability and give you access to the PDF version of this book. Desktop Survival Guides include Data Science, GNU/Linux, and MLHub. Books available on Amazon include Data Mining with Rattle and Essentials of Data Science. Popular open source software includes rattle, wajig, and mlhub. Hosted by Togaware, a pioneer of free and open source software since 1984. Copyright © 1995-2022 Graham.Williams@togaware.com Creative Commons Attribution-ShareAlike 4.0
