How can I create a correlation matrix in R

Question

I have 92 set of data of same type   I want to make a correlation matrix for any two combination possible   i e  I want a matrix of 92 x92   such that element  ci cj  should be correlation between ci and cj   How do I do that

User · Accepted Answer

An example    d  lt- data frame x1 rnorm 10                    x2 rnorm 10                    x3 rnorm 10   cor d    get correlations  returns matrix

User · Answer

You could use  corrplot  package    d  lt - data frame x1 rnorm 10                    x2 rnorm 10                    x3 rnorm 10   M  lt - cor d    get correlations  library  corrplot    package corrplot corrplot M  method    circle    plot matrix     More information here  http   cran r-project org web packages corrplot vignettes corrplot-intro html

User · Answer

The cor function will use the columns of the matrix in the calculation of correlation  So  the number of rows must be the same between your matrix x and matrix y  Ex   set seed 1  x  lt - matrix rnorm 20   nrow 5  ncol 4  y  lt - matrix rnorm 15   nrow 5  ncol 3  COR  lt - cor x y  COR image x seq dim x  2    y seq dim y  2    z COR  xlab  quot x column quot   ylab  quot y column quot   text expand grid x seq dim x  2    y seq dim y  2     labels round c COR  2     Edit  Here is an example of custom row and column labels on a correlation matrix calculated with a single matrix  png  quot corplot png quot   width 5  height 5  units  quot in quot   res 200  op  lt - par mar c 6 6 1 1   ps 10  COR  lt - cor iris  1 4   image x seq nrow COR    y seq ncol COR    z cor iris  1 4    axes F  xlab  quot  quot   ylab  quot  quot   text expand grid x seq dim COR  1    y seq dim COR  2     labels round c COR  2   box   axis 1  at seq nrow COR    labels   rownames COR   las 2  axis 2  at seq ncol COR    labels   colnames COR   las 1  par op  dev off

User · Answer

Have a look at qtlcharts  It allows you to create interactive correlation matrices   library qtlcharts  data iris  iris Species  lt - NULL iplotCorr iris  reorder TRUE      It s more impressive when you correlate more variables  like in the package s vignette

User · Answer

There are other ways to achieve this here   Plot correlation matrix into a graph   but I like your version with the correlations in the boxes  Is there a way to add the variable names to the x and y column instead of just those index numbers  For me  that would make this a perfect solution  Thanks   edit  I was trying to comment on the post by  Marc in the box   but I clearly don t know what I m doing  However  I did manage to answer this question for myself   if d is the matrix  or the original data frame  and the column names are what you want  then the following works   axis 1  1 dim d  2   colnames d   las 2  axis 2  1 dim d  2   colnames d   las 2    las 0 would flip the names back to their normal position  mine were long  so I used las 2 to make them perpendicular to the axis   edit2  to suppress the image   function printing numbers on the grid  otherwise they overlap your variable labels   add xaxt  n   e g    image x seq dim x  2    y seq dim y  2    z COR  col rev heat colors 20    xlab  x column   ylab  y column   xaxt  n

[r] How can I create a correlation matrix in R?

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