| str() |
Compactly Display the Structure of an Arbitrary R Object |
str(log) |
'data.frame': 7 obs. of 2 variables: |
| pmin(), pmax() |
pmax and pmin take one or more vectors (or matrices) as arguments and return a single vector giving the ‘parallel’ maxima (or minima) of the vectors. |
Data_ori <- transform(Data_ori, days_Event = pmin(Data_ori$days_20111231OD1, Data_ori$days_OD2OD1, Data_ori$days_Endo1OD1, Data_ori$days_Ext1OD1, na.rm=TRUE)) |
get the min_day of each row (recoreds) |
| table() |
table uses the cross-classifying factors to build a contingency table of the counts at each combination of factor levels. |
table1 <-as.data.frame(table(Data_ori$days_Event)) |
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| hist() |
computes a histogram of the given data values |
hist(as.numeric(Data_ori$days_Event)) |
create a histogram |
| attach(), detach() |
The database is attached to the R search path. Detach Objects from the Search Path |
attach(Data_ori) |
database is searched by R when evaluating a variable, so objects in the database can be accessed by simply giving their names. |
| names() |
The Names of an Object |
names(Data_ori) |
|
| gsub() |
Pattern Matching and Replacement |
Data_ori$OD1stRDYes <- gsub("NULL",0, Data_ori$OD1stRDYes) |
replace NULL with '0' |
| is.na() |
‘Not Available’ / Missing Values |
Data_ori [is.na(Data_ori )] <- 0 |
replace missing values with '0' |
| substr() |
Substrings of a Character Vector |
Data_ori$ToothPosition <- substr(Data_ori$IPID, 1, 2) |
extract first 2 characters |
| sub() |
Pattern Matching and Replacement |
Data_ori$DateOD1st <- sub('(.{4})(.{2})(.{2})', "\1-\2-\3", Data_ori$Date_OD_1st) |
convert a string to date |
| as.Date() |
Date Conversion Functions to and from Character |
Data_ori$days_20111231OD1 <- as.Date(as.character('2011-12-31'), format="%Y-%m-%d") - as.Date(as.character(Data_ori$DateOD1st), format="%Y-%m-%d") |
Count number of days since a specific date |
| as.character() |
Character Vectors |
Data_ori$days_20111231OD1 <- as.Date(as.character('2011-12-31'), format="%Y-%m-%d") - as.Date(as.character(Data_ori$DateOD1st), format="%Y-%m-%d") |
Count number of days since a specific date |
| transform() |
Transform an Object, for Example a Data Frame |
Data_ori <- transform(Data_ori, days_Event = pmin(Data_ori$days_20111231OD1, Data_ori$days_OD2OD1, Data_ori$days_Endo1OD1, Data_ori$days_Ext1OD1, na.rm=TRUE)) |
add a column to dataframe for Count number of survival days |
| select(){dplyr} |
|
survdata_run <- dplyr::select(Data_Analysis, 1,3:9,17) |
select variables |
| sample() |
Random Samples and Permutations |
Data1 <- Data1[sample(nrow(Data1), 50000), ] |
random select records |
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