Basics
| q() |
Quit |
| <- |
Assign |
| m[,2] |
Column 2 of matrix m |
| m[,2:5] or m[,c(2,3,4,5)] |
Columns 2-5 |
| NA |
Missing data |
| require(package_name) |
Load a package |
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Control flow
| for (i1 in vector1) |
Repeat what follows |
| if (condition1) ... else ... |
Conditional |
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Help
| help(command) |
Quick help for a command |
| help.start() |
Start browser help |
| help(package=package_name) |
Help with a package |
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Arithmetic
| %*% |
Matrix multiplication |
| %/%, ^, %%, sqrt() |
Integer division, power, modulus,square root |
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Input and Output
| source("file1") |
Run the commands in a file |
| read.table("file1") |
Read in data from a file |
| scan("file1") |
Read in a file as vector |
| write(object,"file1") |
Writes an R object to a file |
| write.table(data.frame,"file1") |
Writes a table to a file |
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Graphics
| plot(), barplot(), boxplot(), stem(), hist() |
Basic plots |
| matplot() |
Matrix plot |
| pairs(matrix1) |
Scatterplots |
| qqplot() |
Quantile-quantile plot |
| qqnorm(), qqline() |
Fit normal distribution |
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Managing Variables and Objects
| ls() |
List all active objects |
| rm(object1) |
Remove an object |
| dim(matrix1) |
Dimensions of a matrix |
| dimnames(matrix1) |
Names of dimensions of a matrix |
| length(vector1) |
Length of vector1 |
| 1:3 |
Vector (1,2,3) |
| c(1,2,3) |
Same vector (1,2,3) |
| rep(x,n) |
Repeat vector x, n times |
| cbind(a1,b1,c1), rbind(a1,b1,c1) |
binds columns or rows into a matrix |
| merge(df1,df2) |
Merge data frames |
| cbind(x1,x2) |
Bind vectors x1 and x2 as columns of a matrix |
| rbind(x1,x2) |
Bind vectors x1 and x2 as rows of a matrix |
| merge(df1,df2) |
Merge data frames |
| matrix(vector1,r1,c1) |
Make vector1 into a matrix with r1 rows and c1 columns |
| data.frame(v1,v2) |
Make a data frame from vectors v1 and v2 |
| as.factor(), as.matrix(), as.vector() |
Conversion |
| is.factor(), is.matrix(), is.vector() |
What it is |
| t() |
Switch rows and columns |
| which(x1==a1) |
Returns indices of x1 where x1==a1 |
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Statistics
| max(), min(), mean(), median(), sum()}, var() |
as named |
| summary(data.frame) |
Prints statistics |
| rank(), sort() |
as named |
| ave(x1,y1) |
Averages of x1 grouped by factor y1 |
| by() |
Apply function to data frame by factor |
| apply(x1,n1,function1) |
Apply function1 on rows (n1=1) or columns (n1=2) of x1 |
| tapply(x1,list1,function1) |
Apply function1 to x1 by list1 |
| table() |
Make a table |
| tabulate() |
Tabulate a vector |
| t.test() |
t-test |
| aov(), anova(), lm(), glm() |
Linear and nonlinear models, anova |
| chisq.test(matrix1) |
Chi-square test on matrix matrix1 |
| cor(x1) |
Correlation |
| cor.test(x1,x2) |
Test correlation |
| binom.test() |
Sign test |
| fisher.test() |
Fisher exact test |
| friedman.test() |
Friedman test |
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