TA week2
Alex
2018/03/22
Outline
- Data Frame in R
- Data Input and Output with R
- Basic Logical Operators
Data Frame in R
What is DataFrame
- one of the main tools for data analysis with R
- multiple types of data (more general than matrices)
Basic Operation
- dim()
- nrow()
- ncol()
- ...
- str()
- summary()
Data Input and Output with R
Input .csv file
- read.csv(file_path)
- read.table(file_path)
- fread(file_path)
- watchout your path!
Input excel file
- install the package (open as admin)
-
install.packages('readxl',repos="http://cran.rstudio.com/")
-
library(readxl)
-
- excel_sheets(file)
- read_excel(file, sheet = sheet)
Output to csv
write.csv(df, file = file_name)
Output to excel
- install package "xlsx"
- install java for 64 bit
Sys.setenv(JAVA_HOME='C:\\Program Files\\Java\\jre7') # for 64-bit version
Sys.setenv(JAVA_HOME='C:\\Program Files (x86)\\Java\\jre7') # for 32-bit version
library(xlsx)
write.xlsx(df, file = file_name)
Logical Operators and Control Flow
Logical Operators
- ==
- !=
- >=
- <=
- >
- <
- %in%
- &
- |
- &&
- ||
Control Flow (1/3) - if else
if (condition) {
# do something ...
}
if (cond.) {
# do something ...
} else {
# do the other ...
}
if (cond.) {
# do something ...
} else if (cond. 2) {
# do another ...
} else if (cond. 3) {
# do another ...
} else {
# do another ...
}
if (condition) { ... } [ else if ] ... [ else ]
Control Flow (2/3) - while
while (condition) {
# do something ...
}
while (condition) {
# do something ...
...
break
}
while (condition) { ... }
Control Flow (3/3) - for
my_vec <- c(1,2,3,4,5)
for (temp_var in vec){
print(temp_var)
}
for (i in 1:length(vec)){
print(vec[i])
}
for ( ... ) {
...
break
...
next
}
for (temporary_variable in object) { ... }
something cool
- ifelse
- function
- apply
- pipe
- mode() vs typeof() vs class()
888888888888888
R_Basic_week2
By a136489
R_Basic_week2
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