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### 46 Cards in this Set

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 Matrix (N * T) into Vector. (i-1)*T + t Type of an object? class(obj) Eliminate the effect of class. unclass(obj) Levels of a factor? levels(factor) What is a data.frame? A list made into a matrix. Formating in C. formatC(foo, digits=3) Formating in C to obtain integers. formatC(foo, format="d") Intersection between two vectors. intersect(vec1,vec2) Belong to a set. belong(element,set) FALSE or TRUE Demonstration of plotting maths. demo(plotmath) Including mathematical formulaes. expression() Combingin maths and variables. bquote() Horizontal axis labels. par(las=1) Margin intervals. par(mai=c(1,1,1,1)) Direction of par(mai=c(1,1,1,1)) bottom, left, top, right. Order and apply an order. o <- order[vec] order.vec <- vec[o] Differences between two sets. setdiff(v1,v2) Select type of output in SCAN. scan(foo.txt, what="character) Add a grid to a graph. grid(Number_Cells_X, Number_Cells_Y, lwd=2) P-value from ANOVA object. anova\$p F-value from ANOVA object. anova\$F 1:3 - 2 c(-1,0,1) 1:3*2 c(2,4,6) Close R. q() Fit a linear model with DESIGN matrix. lm.fit(X[n*p], y[n]) Fixed and Random Coefficients in LME. model\$coefficients Factor to numeric as.numeric(as.vector(factor)) Is a missing value? is.na(value) Max removing missing values. max(vec, na.rm=TRUE) Random/Fixed effects from a model. mod\$coefficients Bash within R. system("mkdir foo") Set working directory. setwd() Suppress a letter in a string. strsplit( "foo\", "\") Write entries in one single column. write(foo, foo.txt, ncolumns=1) Matrix Product. A %*% B xAx x %*% A %*% x Matrix Inverse solve(A) xA^{-1}x x %*% solve(A,x) Permission problem when installing new package. chown 777 -R R Difference between order() and rank(). x[order(x)] is equivalent to sort(x). rank(x) is just the ranks. gedelete gedelete Difference between && and & && apply to vectors of length 1. & apply elementwise to vectors. Difference between || and | || apply to vectors of length 1. | apply elementwise to vectors. Syntax for while. while (condition) expr Maximum likelihood estimation. mle(-loglik) Plot Time series. plot(as.ts(mat))