Convert data.frame columns from factors to characters

Just following on Matt and Dirk. If you want to recreate your existing data frame without changing the global option, you can recreate it with an apply statement:

bob <- data.frame(lapply(bob, as.character), stringsAsFactors=FALSE)

To replace only factors:
i <- sapply(bob, is.factor)
bob[i] <- lapply(bob[i], as.character)

How to Count Unique/Distinct Values of A Variable in R

base R:


length(unique(mydata$colA))

Summarize data by group in R

tapply(a$avg_cpc_1d, a$avg_pos, mean)
aggregate(avg_cpc_1d~avg_pos, a, mean)



clk_summ<-data.frame(group_by(clk2, OND)%>%summarise(cnt=n()))

a<-tapply(gp$txn,gp$product_ln_name,sum)

112down votefavorite 86	I have R data frame like this: age group 1 23.0883 1 2 25.8344 1 3 29.4648 1 4 32.7858 2 5 33.6372 1 6 34.9350 1 7 35.2115 2 8 35.2115 2 9 35.2115 2 10 36.7803 1 ... I need to get data frame in the following form: group mean sd 1 34.5 5.6 2 32.3 4.2 ... Group number may vary, but their names and quantity could be obtained by calling levels(factor(data$group)) What manipulations should be done with the data to get the result? r data-transformation shareimprove this question edited Mar 13 '11 at 15:20 asked Mar 13 '11 at 12:02 Yuriy Petrovskiy 1,48641624
closed as off-topic by gung, user777, kjetil b halvorsen, John, Peter Flom♦ Sep 11 '15 at 23:23 This question appears to be off-topic. The users who voted to close gave this specific reason: "This question appears to be off-topic because EITHER it is not about statistics, machine learning, data analysis, data mining, or data visualization, OR it focuses on programming, debugging, or performing routine operations within a statistical computing platform. If the latter, you could try the support links we maintain." – gung, user777, kjetil b halvorsen, John, Peter Flom If this question can be reworded to fit the rules in the help center, please edit the question.
	the commas in the result data frame mean something special, or is it just the decimal point? – mpiktas Mar 13 '11 at 12:46 3 I suspected that. All of the Europe uses comma except the British. – mpiktas Mar 13 '11 at 13:04 4 Despite not being British, I prefer dot for decimal separator. – Roman Luštrik Mar 14 '11 at 12:17 15 The British also drive on the wrong side – RockScience Mar 15 '11 at 11:23 5 @RockScience: We drive on the right side - the left side. Everyone else is on the wrong right side! (And we wonder why people struggle with our language!) – Mark K Cowan Sep 16 '13 at 16:30 show 3 more comments

9 Answers

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up vote101down voteaccepted

Here is the plyr one line variant using ddply: dt <- data.frame(age=rchisq(20,10),group=sample(1:2,20,rep=T)) ddply(dt,~group,summarise,mean=mean(age),sd=sd(age)) Here is another one line variant using new package data.table. dtf <- data.frame(age=rchisq(100000,10),group=factor(sample(1:10,100000,rep=T))) dt <- data.table(dtf) dt[,list(mean=mean(age),sd=sd(age)),by=group] This one is faster, though this is noticeable only on table with 100k rows. Timings on my Macbook Pro with 2.53 Ghz Core 2 Duo processor and R 2.11.1: > system.time(aa <- ddply(dtf,~group,summarise,mean=mean(age),sd=sd(age))) utilisateur système écoulé 0.513 0.180 0.692 > system.time(aa <- dt[,list(mean=mean(age),sd=sd(age)),by=group]) utilisateur système écoulé 0.087 0.018 0.103 Further savings are possible if we use setkey: > setkey(dt,group) > system.time(dt[,list(mean=mean(age),sd=sd(age)),by=group]) utilisateur système écoulé 0.040 0.007 0.048 shareimprove this answer edited Oct 25 '14 at 10:16 answered Mar 13 '11 at 12:44 mpiktas 22.7k44493

1 Thanks for the update and the benchmark info! – chl♦ Mar 15 '11 at 10:24 1 @chl, it gave me a chance to try out this new data.table package. It looks really promising. – mpiktas Mar 15 '11 at 12:54 5 +6000 for data.table. It really is so much faster than ddply, even for me on datasets smaller than 100k (I have one with just 20k rows). Must be something to do with the functions I am applying, but ddply will take minutes and data.table a few seconds. – atomicules Sep 22 '11 at 15:22 Simple typo: I think you meant dt <- data.table(dtf) instead of dt <- data.table(dt) in the second code block. That way, you are creating the data table from a data frame instead of from the dtfunction from the stats package. I tried editing it, but I cannot do edits under six characters. – Christopher Bottoms Oct 24 '14 at 18:50  Thanks, fixed it. – mpiktas Oct 25 '14 at 10:16 show 1 more comment

Sort A Data Frame In R

Here are 2 ways to sort a data frame in R. One is traditional way. The other one is using dplyr.


gp2<-gp[order(gp$txn),]

gp3<-arrange(gp,txn)

Export Text Mining

If you export the training data set out of the Text Topic node by running code in a SAS Code node that follows the Text Topic node:

/***********************************************************************************

SAS INSTITUTE INC. IS PROVIDING YOU WITH THE COMPUTER SOFTWARE CODE INCLUDED WITH THIS AGREEMENT ("CODE") ON AN "AS IS" BASIS, AND AUTHORIZES YOU TO USE THE CODE SUBJECT TO THE TERMS HEREOF.  BY USING THE CODE, YOU AGREE TO THESE TERMS.  YOUR USE OF THE CODE IS AT YOUR OWN RISK.  SAS INSTITUTE INC. MAKES NO REPRESENTATION OR WARRANTY, EXPRESS OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, NONINFRINGEMENT AND TITLE, WITH RESPECT TO THE CODE.

*************************************************************************************/

libname mylib 'c:\data';

data mylib.texttopic_output;

 set &em_import_data;

run;

The following variables are outputted as part of the exported training data set:

Original variables

TextTopic_raw<n>

TextTopic_<n>

_Document_

If you export the training data set out of the Text Cluster node by running code in a SAS Code node that follows the Text Cluster node:

/***********************************************************************************

SAS INSTITUTE INC. IS PROVIDING YOU WITH THE COMPUTER SOFTWARE CODE INCLUDED WITH THIS AGREEMENT ("CODE") ON AN "AS IS" BASIS, AND AUTHORIZES YOU TO USE THE CODE SUBJECT TO THE TERMS HEREOF.  BY USING THE CODE, YOU AGREE TO THESE TERMS.  YOUR USE OF THE CODE IS AT YOUR OWN RISK.  SAS INSTITUTE INC. MAKES NO REPRESENTATION OR WARRANTY, EXPRESS OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, NONINFRINGEMENT AND TITLE, WITH RESPECT TO THE CODE.

*************************************************************************************/

libname mylib 'c:\data';

data mylib.textcluster_output;

 set &em_import_data;

run;

The following variables are outputted as part of the exported training data set:

Original variables

TextCluster_cluster

TextCluster_SVD<n>

TextCluster_prob<n>

_Document_