10.41 Effect on Data Storage

20180721 When the names of the variables within a dataset are changed R does not make a complete new copy of the dataset. Instead, the actual data in the column remains in tack whilst the variable itself (ds) references a new memory location where the new variable names get noted. The underlying data within the table is unaffected.

lobstr::ref(weather)

## █ [1:0x5f1012bcb290] <tibble[,24]> 
## ├─Date=[2:0x5f10075c3860] <date> 
## ├─Location=[3:0x5f1005a3c0f0] <chr> 
## ├─MinTemp=[4:0x5f1012bca6e0] <dbl> 
## ├─MaxTemp=[5:0x5f100b47df80] <dbl> 
## ├─Rainfall=[6:0x5f100e6eba60] <dbl> 
## ├─Evaporation=[7:0x5f100c10ac60] <dbl> 
## ├─Sunshine=[8:0x5f100738e270] <dbl> 
## ├─WindGustDir=[9:0x5f100a1d49c0] <ord> 
## ├─WindGustSpeed=[10:0x5f100eec5350] <dbl> 
## ├─WindDir9am=[11:0x5f100bc707a0] <ord> 
## ├─WindDir3pm=[12:0x5f10031fefb0] <ord> 
## ├─WindSpeed9am=[13:0x5f1008ceba20] <dbl> 
## ├─WindSpeed3pm=[14:0x5f1004b2c960] <dbl> 
## ├─Humidity9am=[15:0x5f100212e180] <int> 
## ├─Humidity3pm=[16:0x5f100e750e50] <int> 
## ├─Pressure9am=[17:0x5f10050e16c0] <dbl> 
## ├─Pressure3pm=[18:0x5f100c889690] <dbl> 
## ├─Cloud9am=[19:0x5f100c817120] <int> 
## ├─Cloud3pm=[20:0x5f100c792b10] <int> 
## ├─Temp9am=[21:0x5f100bac8560] <dbl> 
## ├─Temp3pm=[22:0x5f1008ee8450] <dbl> 
## ├─RainToday=[23:0x5f1009eda260] <fct> 
## ├─RISK_MM=[24:0x5f100da002e0] <dbl> 
## └─RainTomorrow=[25:0x5f100c421a50] <fct>

lobstr::ref(ds)

## █ [1:0x5f1013d95870] <tibble[,24]> 
## ├─date=[2:0x5f10090e2910] <date> 
## ├─location=[3:0x5f1006d5ceb0] <chr> 
## ├─min_temp=[4:0x5f100955aa90] <dbl> 
## ├─max_temp=[5:0x5f10099d2d90] <dbl> 
## ├─rainfall=[6:0x5f1009b8df70] <dbl> 
## ├─evaporation=[7:0x5f10086882b0] <dbl> 
## ├─sunshine=[8:0x5f1008843490] <dbl> 
## ├─wind_gust_dir=[9:0x5f10071fc620] <ord> 
## ├─wind_gust_speed=[10:0x5f10089fe670] <dbl> 
## ├─wind_dir_9am=[11:0x5f1009354370] <ord> 
## ├─wind_dir_3pm=[12:0x5f10098df520] <ord> 
## ├─wind_speed_9am=[13:0x5f100a638a40] <dbl> 
## ├─wind_speed_3pm=[14:0x5f100a7f3c20] <dbl> 
## ├─humidity_9am=[15:0x5f100a53f360] <int> 
## ├─humidity_3pm=[16:0x5f1006f18090] <int> 
## ├─pressure_9am=[17:0x5f100a9aee00] <dbl> 
## ├─pressure_3pm=[18:0x5f100ab69fe0] <dbl> 
## ├─cloud_9am=[19:0x5f100762a380] <int> 
## ├─cloud_3pm=[20:0x5f1009715c70] <int> 
## ├─temp_9am=[21:0x5f100ad251c0] <dbl> 
## ├─temp_3pm=[22:0x5f100aee03a0] <dbl> 
## ├─rain_today=[23:0x5f10080aa160] <fct> 
## ├─risk_mm=[24:0x5f100b09b580] <dbl> 
## └─rain_tomorrow=[25:0x5f100b256760] <fct>

---

Your 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