Bring a small dataset of bridges into R as a dataframe and call a subset of that dataframe.
Lets begin by bringing the data into R using url() and read.csv() and checking out how to top five rows look.
bridgedata <- read.csv(url('https://archive.ics.uci.edu/ml/machine-learning-databases/bridges/bridges.data.version1'))
bridgedf <- as.data.frame(bridgedata)
names(bridgedf) = c("ID","River","StateNum","YearBuilt","Purpose","Length","Lanes","Clear","DeckType","Material","Span","Rel","Type")
head(bridgedf,5)## ID River StateNum YearBuilt Purpose Length Lanes Clear DeckType
## 1 E2 A 25 1819 HIGHWAY 1037 2 N THROUGH
## 2 E3 A 39 1829 AQUEDUCT ? 1 N THROUGH
## 3 E5 A 29 1837 HIGHWAY 1000 2 N THROUGH
## 4 E6 M 23 1838 HIGHWAY ? 2 N THROUGH
## 5 E7 A 27 1840 HIGHWAY 990 2 N THROUGH
## Material Span Rel Type
## 1 WOOD SHORT S WOOD
## 2 WOOD ? S WOOD
## 3 WOOD SHORT S WOOD
## 4 WOOD ? S WOOD
## 5 WOOD MEDIUM S WOODSummarizing the data with summary() to help get familiar with the df.
summary(bridgedf)## ID River StateNum YearBuilt Purpose
## E10 : 1 A:49 28 : 5 Min. :1819 AQUEDUCT: 4
## E100 : 1 M:40 39 : 5 1st Qu.:1884 HIGHWAY :70
## E101 : 1 O:15 25 : 4 Median :1903 RR :32
## E102 : 1 Y: 3 27 : 4 Mean :1906 WALK : 1
## E103 : 1 29 : 4 3rd Qu.:1928
## E105 : 1 1 : 3 Max. :1986
## (Other):101 (Other):82
## Length Lanes Clear DeckType Material Span Rel
## ? :26 ?:16 ?: 2 ? : 6 ? : 2 ? :16 ? : 5
## 1000 :10 1: 4 G:80 DECK :15 IRON :11 LONG :30 F :58
## 1200 : 5 2:60 N:25 THROUGH:86 STEEL:79 MEDIUM:53 S :29
## 1500 : 2 4:23 WOOD :15 SHORT : 8 S-F:15
## 2000 : 2 6: 4
## 2300 : 2
## (Other):60
## Type
## SIMPLE-T:44
## WOOD :15
## ARCH :13
## CANTILEV:11
## SUSPEN :11
## CONT-T :10
## (Other) : 3Select for a subset of the dataframe where all bridges have a length greater than 1500 and returns columns for StateNum, Length, Pupose, and Material
sublongbr <- subset(bridgedf, as.numeric(as.character(Length)) > 1500, select = c(StateNum, Length, Purpose, Material))## Warning in eval(e, x, parent.frame()): NAs introduced by coercionsublongbr## StateNum Length Purpose Material
## 31 41 4558 RR STEEL
## 41 9 2367 HIGHWAY STEEL
## 44 37 4000 RR STEEL
## 45 14 2264 RR STEEL
## 46 15 2000 RR STEEL
## 48 38 2000 HIGHWAY STEEL
## 50 34 1850 HIGHWAY STEEL
## 52 35 3000 RR STEEL
## 57 2 1504 RR STEEL
## 60 36 1730 HIGHWAY STEEL
## 61 49 1620 RR STEEL
## 62 43 1652 HIGHWAY STEEL
## 64 10 2210 RR STEEL
## 65 41 2822 RR STEEL
## 67 37 2300 RR STEEL
## 68 31 2122 RR STEEL
## 71 32 2365 HIGHWAY STEEL
## 74 46 1770 HIGHWAY STEEL
## 75 38 1508 HIGHWAY STEEL
## 76 5 2663 HIGHWAY STEEL
## 78 30 2678 HIGHWAY STEEL
## 79 20 2220 HIGHWAY STEEL
## 81 17 2250 HIGHWAY STEEL
## 85 11 1690 HIGHWAY STEEL
## 86 34 1800 HIGHWAY STEEL
## 89 38.5 1710 HIGHWAY STEEL
## 90 48 2160 HIGHWAY STEEL
## 95 14 2423 HIGHWAY STEEL
## 97 37 2300 HIGHWAY STEEL
## 99 47 1700 HIGHWAY STEEL
## 102 9 2213 HIGHWAY STEEL
## 104 44 3756 HIGHWAY STEEL