I have a database with multiple variables, both numerical and categorical. I would like to have summary descriptive statistics with R studio only for categorical variables (frequency, percentage) and i was thinking about a subset of the database isolated with a column list created with a function and then passing it to sapply -> prop.table.
Unfortunately I'm stucked and i can only detect through the columns if they're categorical or not.
Thanks in advance,
Angelo
There are many ways to iterate through your factor columns.
For example:
d <- data.frame( A=numeric(), B=logical(), C=character() )
for(col in which(sapply(d, is.factor)))
print(col, names(d)[col], summary(d[,col])) # print whatever statistics you want
Is this what you want?
Related
I have a data frame with 100+ variables listed in columns, and each subject in rows. I'd like to loop through each column to perform an ANOVA, and while the loop function works fine the step I am stuck on is listing which columns to loop through. Currently I can set these by manually typing/pasting each variable name but this is obviously not practical.
Currently the loop runs through my list of vars, to get this I currently just type the name of these columns manually...
variables <- vars(height, width, strength)
Which only loops for those selected 3 out of 100+ variables that I have had to manually type in.
I had thought I could list the range of column names for dataframe df between columns 3 to 100 within the vars expression as below...
variables <- vars(colnames(df[3:100]))
This just provides one variable of the name colnames(df[3:100]).
Any ideas to avoid typing or manually inserting commas/removing quotation marks from 100+ different variable names? Thanks in advance.
Consider do.call which is shorthand for expanded list of arguments to a function. Specifically, below:
variables <- do.call(vars, colnames(df)[3:100])
is equivalent to expanded version:
variables <- vars(colnames(df)[3], colnames(df)[4], ..., colnames(df)[100])
I'm trying to get the correlation coefficient for corresponding columns of two csv files. I simply use the followings but get errors. consider each csv file has 50 columns
first values <- read.csv("")
second values <- read.csv("")
correlation.csv <- cor(x= first values , y=second values, method="spearman)
But i get x' must be numeric error!
subset of one csv file
Thanks for your help
The read.table function and all of it's derivatives return a data.frame which is an R list object. The mapply function processes lists in "parallel". If the matching columns are in the same order in the two datasets and have the same number of rows and do not have spaces in their names, it would be as simple as:
mapply(cor, first_values , second_values)
If it's more complicated tahn that, then you need to fill in the missing details with example data by editing the question (not by responding in comments.)
There must be some categorical variable in X.So you can first separate that categorical variable from X and then use X in cor() function.
Dear Friends I would appreciate if someone can help me in some question in R.
I have a data frame with 8 variables, lets say (v1,v2,...,v8).I would like to produce groups of datasets based on all possible combinations of these variables. that is, with a set of 8 variables I am able to produce 2^8-1=63 subsets of variables like {v1},{v2},...,{v8}, {v1,v2},....,{v1,v2,v3},....,{v1,v2,...,v8}
my goal is to produce specific statistic based on these groupings and then compare which subset produces a better statistic. my problem is how can I produce these combinations.
thanks in advance
You need the function combn. It creates all the combinations of a vector that you provide it. For instance, in your example:
names(yourdataframe) <- c("V1","V2","V3","V4","V5","V6","V7","V8")
varnames <- names(yourdataframe)
combn(x = varnames,m = 3)
This gives you all permutations of V1-V8 taken 3 at a time.
I'll use data.table instead of data.frame;
I'll include an extraneous variable for robustness.
This will get you your subsetted data frames:
nn<-8L
dt<-setnames(as.data.table(cbind(1:100,matrix(rnorm(100*nn),ncol=nn))),
c("id",paste0("V",1:nn)))
#should be a smarter (read: more easily generalized) way to produce this,
# but it's eluding me for now...
#basically, this generates the indices to include when subsetting
x<-cbind(rep(c(0,1),each=128),
rep(rep(c(0,1),each=64),2),
rep(rep(c(0,1),each=32),4),
rep(rep(c(0,1),each=16),8),
rep(rep(c(0,1),each=8),16),
rep(rep(c(0,1),each=4),32),
rep(rep(c(0,1),each=2),64),
rep(c(0,1),128)) *
t(matrix(rep(1:nn),2^nn,nrow=nn))
#now get the correct column names for each subset
# by subscripting the nonzero elements
incl<-lapply(1:(2^nn),function(y){paste0("V",1:nn)[x[y,][x[y,]!=0]]})
#now subset the data.table for each subset
ans<-lapply(1:(2^nn),function(y){dt[,incl[[y]],with=F]})
You said you wanted some statistics from each subset, in which case it may be more useful to instead specify the last line as:
ans2<-lapply(1:(2^nn),function(y){unlist(dt[,incl[[y]],with=F])})
#exclude the first row, which is null
means<-lapply(2:(2^nn),function(y){mean(ans2[[y]])})
I have a df with over 30 columns and over 200 rows, but for simplicity will use an example with 8 columns.
X1<-c(sample(100,25))
B<-c(sample(4,25,replace=TRUE))
C<-c(sample(2,25,replace =TRUE))
Y1<-c(sample(100,25))
Y2<-c(sample(100,25))
Y3<-c(sample(100,25))
Y4<-c(sample(100,25))
Y5<-c(sample(100,25))
df<-cbind(X1,B,C,Y1,Y2,Y3,Y4,Y5)
df<-as.data.frame(df)
I wrote a function that melts the data generates a plot with X1 giving the x-axis values and faceted using the values in B and C.
plotdata<-function(l){
melt<-melt(df,id.vars=c("X1","B","C"),measure.vars=l)
plot<-ggplot(melt,aes(x=X1,y=value))+geom_point()
plot2<-plot+facet_grid(B ~ C)
ggsave(filename=paste("X_vs_",l,"_faceted.jpeg",sep=""),plot=plot2)
}
I can then manually input the required Y variable
plotdata("Y1")
I don't want to generate plots for all columns. I could just type the column of interest into plotdata and then get the result, but this seems quite inelegant (and time consuming). I would prefer to be able to manually specify the columns of interest e.g. "Y1","Y3","Y4" and then write a loop function to do all those specified.
However I am new to writing for loops and can't find a way to loop in the specific column names that are required for my function to work. A standard for(i in 1:length(df)) wouldn't be appropriate because I only want to loop the user specified columns
Apologies if there is an answer to this is already in stackoverflow. I couldn't find it if there was.
Thanks to Roland for providing the following answer:
Try
for (x in c("Y1","Y3","Y4")) {plotdata(x)}
The index variable doesn't have to be numeric
I have two columns of paired values in a data frame, I want to bin the data in one column using the cut2 function from the Hmisc package so that there are at least say 25 data points in each bin. I however need the corresponding values from the other column. Is there a convenient way for that using R? I have to bin the column B.
A B
-10.834510 1.680173
11.012966 1.866603
-16.491415 1.868667
-14.485036 1.900002
2.629104 1.960929
-3.597291 2.005348
.........
It's not clear what you mean by wanting the "corresponding values of the other column". The first part is easy to accomplish using the g (# of groups) argument:
dfrm$Agrp <- cut2(dfrm$A, g=trunc(length(dfrm$A)/25) )
You can aggregate means or medians of B within Agrp's using tapply or ave or one of the Hmisc summary functions. There are several worked examples in one of today's questions: How to get Summary statistics by group as well as many other examples of using those functions or aggregate or the pkg:plyr functions.
Given that the number of B values will not necessarily be constant across groups the only way I can think to deliver the individual values by A-grouped-value would be with split. I added an extra row to illustrate that a non-even split might need to return a list rather than a more "rectangular" object :
dat <- read.table(text="A B
-10.834510 1.680173
11.012966 1.866603
-16.491415 1.868667
-14.485036 1.900002
2.629104 1.960929
-3.597291 2.005348\n 3.5943 3.796", header=TRUE)
dat$Agrp <- cut2(dat$A, g=trunc(length(dat$A)/3) )
split(dat$B, dat$Agrp)
#-----
$`[-16.49, 2.63)`
[1] 1.680173 1.868667 1.900002 2.005348
$`[ 2.63,11.01]`
[1] 1.866603 1.960929 3.796000
If you want the vector of values on which the splits were done then that can be accomplished by using regex on levels(dat$Agrp).