Читать книгу The Big R-Book - Philippe J. S. De Brouwer - Страница 174

Once the data is loaded in R it is important to be able to make selections and further prepare the data.We will come back to this in much more detail in Part IV “DataWrangling” on page 335, but present here already some essentials.

# get the maximum exchange rate maxCAD <- max(data$CAD) # use SQL-like selection d0 <- subset(data, CAD == maxCAD) d1 <- subset(data, CAD > maxCAD - 0.1) d1[,1] ## [1] 2008-12-30 2008-12-29 2008-12-18 1999-02-03 ## [5] 1999-01-29 1999-01-28 1999-01-27 1999-01-26 ## [9] 1999-01-25 1999-01-22 1999-01-21 1999-01-20 ## [13] 1999-01-19 1999-01-18 1999-01-15 1999-01-14 ## [17] 1999-01-13 1999-01-12 1999-01-11 1999-01-08 ## [21] 1999-01-07 1999-01-06 1999-01-05 1999-01-04 ## 4718 Levels: 1999-01-04 1999-01-05 … 2017-06-05 d2<- data.frame(d1$Date,d1$CAD) d2 ## d1.Date d1.CAD ## 1 2008-12-30 1.7331 ## 2 2008-12-29 1.7408 ## 3 2008-12-18 1.7433 ## 4 1999-02-03 1.7151 ## 5 1999-01-29 1.7260 ## 6 1999-01-28 1.7374 ## 7 1999-01-27 1.7526 ## 8 1999-01-26 1.7609 ## 9 1999-01-25 1.7620 ## 10 1999-01-22 1.7515 ## 11 1999-01-21 1.7529 ## 12 1999-01-20 1.7626 ## 13 1999-01-19 1.7739 ## 14 1999-01-18 1.7717 ## 15 1999-01-15 1.7797 ## 16 1999-01-14 1.7707 ## 17 1999-01-13 1.8123 ## 18 1999-01-12 1.7392 ## 19 1999-01-11 1.7463 ## 20 1999-01-08 1.7643 ## 21 1999-01-07 1.7602 ## 22 1999-01-06 1.7711 ## 23 1999-01-05 1.7965 ## 24 1999-01-04 1.8004 hist(d2$d1.CAD, col = ‘khaki3’)