geofferyzh
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| ################################################# | |
| # Import data from DBMSs # | |
| ################################################# | |
| # The ODBC Interface | |
| library(RODBC) | |
| myconn <-odbcConnect("mydsn", uid="Rob", pwd="xxxxxx") | |
| crimedat <- sqlFetch(myconn, Crime) | |
| pundat <- sqlQuery(myconn, "select * from Punishment") | |
| close(myconn) |
geofferyzh
/ gist:2401403
Created
April 16, 2012 20:45
RinAction - R Data Manipulation - Creating New Variables
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| #-----------------------------------------------------------------------------# | |
| #-----------------------------------------------------------------------------# | |
| # R in Action - Data Management # | |
| #-----------------------------------------------------------------------------# | |
| #-----------------------------------------------------------------------------# | |
| install.packages(c('reshape', 'sqldf')) | |
geofferyzh
/ gist:2401425
Created
April 16, 2012 20:50
RinAction - R Data Manipulation - recode variables
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| ################################################# | |
| ## Recoding variables ## | |
| ################################################# | |
| # Recoding categorical variable | |
| leadership$agecat[leadership$age > 75] <- "Elder" | |
| leadership$agecat[leadership$age > 45 & | |
| leadership$age <= 75] <- "Middle Aged" | |
| leadership$agecat[leadership$age <= 45] <- "Young" |
geofferyzh
/ gist:2401428
Created
April 16, 2012 20:51
RinAction - R Data Manipulation - rename variables
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| ################################################# | |
| ## Renaming variables ## | |
| ################################################# | |
| # using the rename() function in the "reshape" package | |
| install.packages("reshape") | |
| library(reshape) | |
| rename(leadership, c(manager = "managerID", date = "testDate")) |
geofferyzh
/ gist:2401432
Created
April 16, 2012 20:51
RinAction - R Data Manipulation - missing variables
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| ############################################################################# | |
| ## ------------------- Missing Values ----------------------########### | |
| ## 1. missing values in R are represented as NA (not available) # | |
| ## 2. Impossible values (devided by 0) are represented as NaN (not a number)# | |
| ############################################################################# | |
| # Identify missing values using is.na() function | |
| is.na(leadership[6:9]) | |
| y <- c(1,2,3,NA) |
geofferyzh
/ gist:2401435
Created
April 16, 2012 20:52
RinAction - R Data Manipulation - Date Variable
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| ############################################################## | |
| ## ------------ Date Values ------------- | |
| ## Dates are typically entered into R as character strings | |
| ## and then translated into date variables that are stored | |
| ## numerically | |
| ## | |
| ## Date format | |
| ## %d --> Day as a number (0-31) | |
| ## %a --> Abbreviated weekday (Mon, Tue, Fri) | |
| ## %A --> Unabbreviated weekday (Monday, Tuesday) |
geofferyzh
/ gist:2401437
Created
April 16, 2012 20:53
RinAction - R Data Manipulation - Data Type Conversion
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| ############################################################## | |
| ## ------------ Data Type Conversion ------------- | |
| ## Converting one data type to another | |
| ## | |
| ## is.numeric() --> as.numeric() | |
| ## is.character() --> as.character() | |
| ## is.vector() --> as.vector() | |
| ## is.matrix() --> as.matrix() | |
| ## is.data.frame() --> as.data.frame() | |
| ## is.factor() --> as.factor() |
geofferyzh
/ gist:2401440
Created
April 16, 2012 20:54
RinAction - R Data Manipulation - Sort and Merge
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| ################################################# | |
| ## SORT & MERGE ## | |
| ################################################# | |
| ################### | |
| #Sorting a dataset | |
| ################### | |
| attach(leadership) | |
| newdata <- leadership[order(age), ] | |
| newdata |
geofferyzh
/ gist:2401442
Created
April 16, 2012 20:54
RinAction - R Data Manipulation - Subsetting data
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| ################################################# | |
| ## Subsetting Dataset ## | |
| ################################################# | |
| #################### | |
| # Keeping variables | |
| #################### | |
| # method 1 |
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| #-----------------------------------------------------------------------------# | |
| #-----------------------------------------------------------------------------# | |
| # R in Action - Advanced Data Management # | |
| #-----------------------------------------------------------------------------# | |
| #-----------------------------------------------------------------------------# | |
| ################################################# | |
| ## Basic Math Functions ## | |
| ################################################# |