The pipe feature
The pipe feature is an alternative syntax that many programmers find makes their work more efficient. It is explained in the textbook on p. 34.
library(dplyr)
#read in our usual heart data
heart <- read.csv("C:/epi551/heart.csv", header=T)
head(heart)## Age Sex Chest_Pain_Type Resting_Blood_Pressure Serum_Cholesterol
## 1 63 1 1 145 233
## 2 67 1 4 160 286
## 3 67 1 4 120 229
## 4 37 1 3 130 250
## 5 41 0 2 130 204
## 6 56 1 2 120 236
## Fasting_Blood_Sugar Resting_ECG Max_Heart_Rate_Achieved
## 1 1 2 150
## 2 0 2 108
## 3 0 2 129
## 4 0 0 187
## 5 0 2 172
## 6 0 0 178
## Exercise_Induced_Angina ST_Depression_Exercise Peak_Exercise_ST_Segment
## 1 0 2.3 3
## 2 1 1.5 2
## 3 1 2.6 2
## 4 0 3.5 3
## 5 0 1.4 1
## 6 0 0.8 1
## Num_Major_Vessels_Flouro Thalassemia Diagnosis_Heart_Disease diagnosis
## 1 0.0 6.0 0 No
## 2 3.0 3.0 2 Yes
## 3 2.0 7.0 1 Yes
## 4 0.0 3.0 0 No
## 5 0.0 3.0 0 No
## 6 0.0 3.0 0 No#make some changes to the data in three steps
heart2 <- rename(heart,thal=Thalassemia)
heart3 <- mutate(heart2,agemo=Age*12)
heart4 <- filter(heart3,Sex==1)
head(heart4)## Age Sex Chest_Pain_Type Resting_Blood_Pressure Serum_Cholesterol
## 1 63 1 1 145 233
## 2 67 1 4 160 286
## 3 67 1 4 120 229
## 4 37 1 3 130 250
## 5 56 1 2 120 236
## 6 63 1 4 130 254
## Fasting_Blood_Sugar Resting_ECG Max_Heart_Rate_Achieved
## 1 1 2 150
## 2 0 2 108
## 3 0 2 129
## 4 0 0 187
## 5 0 0 178
## 6 0 2 147
## Exercise_Induced_Angina ST_Depression_Exercise Peak_Exercise_ST_Segment
## 1 0 2.3 3
## 2 1 1.5 2
## 3 1 2.6 2
## 4 0 3.5 3
## 5 0 0.8 1
## 6 0 1.4 2
## Num_Major_Vessels_Flouro thal Diagnosis_Heart_Disease diagnosis agemo
## 1 0.0 6.0 0 No 756
## 2 3.0 3.0 2 Yes 804
## 3 2.0 7.0 1 Yes 804
## 4 0.0 3.0 0 No 444
## 5 0.0 3.0 0 No 672
## 6 1.0 7.0 2 Yes 756#make the same changes to the data in one step using %>%
heartpipe <- heart %>% rename(thal=Thalassemia) %>% mutate(agemo=Age*12) %>%
filter(Sex==1)
head(heartpipe)## Age Sex Chest_Pain_Type Resting_Blood_Pressure Serum_Cholesterol
## 1 63 1 1 145 233
## 2 67 1 4 160 286
## 3 67 1 4 120 229
## 4 37 1 3 130 250
## 5 56 1 2 120 236
## 6 63 1 4 130 254
## Fasting_Blood_Sugar Resting_ECG Max_Heart_Rate_Achieved
## 1 1 2 150
## 2 0 2 108
## 3 0 2 129
## 4 0 0 187
## 5 0 0 178
## 6 0 2 147
## Exercise_Induced_Angina ST_Depression_Exercise Peak_Exercise_ST_Segment
## 1 0 2.3 3
## 2 1 1.5 2
## 3 1 2.6 2
## 4 0 3.5 3
## 5 0 0.8 1
## 6 0 1.4 2
## Num_Major_Vessels_Flouro thal Diagnosis_Heart_Disease diagnosis agemo
## 1 0.0 6.0 0 No 756
## 2 3.0 3.0 2 Yes 804
## 3 2.0 7.0 1 Yes 804
## 4 0.0 3.0 0 No 444
## 5 0.0 3.0 0 No 672
## 6 1.0 7.0 2 Yes 756