60
votes
15
answers
1.8K
views
How can I trim leading and trailing white space?
I am having some troubles with leading and trailing white space in a data.frame. For example, I like to take a
62
votes
11
answers
3.1K
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Sample random rows in dataframe
I am struggling to find the appropriate function that would return a specified number of rows picked up random
64
votes
29
answers
2.6K
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Elegant way to check for missing packages and install them?
I seem to be sharing a lot of code with coauthors these days. Many of them are novice/intermediate R users and
56
votes
8
answers
925
views
How to add leading zeros?
I have a set of data which looks something like this: anim <- c(25499,25500,25501,25502,25503,25504) sex
65
votes
9
answers
1.6K
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Combine a list of data frames into one data frame by row
I have code that at one place ends up with a list of data frames which I really want to convert to a single bi
54
votes
12
answers
1.9K
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How can two strings be concatenated?
How can I concatenate (merge, combine) two values? For example I have: tmp = cbind("GAD", "AB") tmp # [,
57
votes
2
answers
2.5K
views
Why is `[` better than `subset`?
When I need to filter a data.frame, i.e., extract rows that meet certain conditions, I prefer to use the subse
61
votes
6
answers
1.9K
views
How do I install an R package from source?
A friend sent me along this great tutorial on webscraping NYtimes with R. I would really love to try it. Howev
53
votes
10
answers
1.8K
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Extracting specific columns from a data frame
I have an R data frame with 6 columns, and I want to create a new dataframe that only has three of the columns
52
votes
5
answers
2.7K
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How to write trycatch in R
I want to write trycatch code to deal with error in downloading from the web. url <- c( "http://stat.e
57
votes
15
answers
1.5K
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How to sum a variable by group
I have a data frame with two columns. First column contains categories such as "First", "Second", "Third", and
57
votes
30
answers
2.1K
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How to find the statistical mode?
In R, mean() and median() are standard functions which do what you'd expect. mode() tells you the intern
57
votes
20
answers
1.6K
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Counting the number of elements with the values of x in a vector
I have a vector of numbers: numbers <- c(4,23,4,23,5,43,54,56,657,67,67,435, 453,435,324,34,456,5
58
votes
11
answers
2.7K
views
Quickly reading very large tables as dataframes
I have very large tables (30 million rows) that I would like to load as a dataframes in R. read.table() has a
58
votes
17
answers
2.1K
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Create an empty data.frame
I'm trying to initialize a data.frame without any rows. Basically, I want to specify the data types for e
59
votes
7
answers
2.1K
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46
votes
15
answers
709
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Drop unused factor levels in a subsetted data frame
I have a data frame containing a factor. When I create a subset of this dataframe using subset or another inde
49
votes
12
answers
2.6K
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The difference between bracket [ ] and double bracket [[ ]] for accessing the elements of a list or dataframe
R provides two different methods for accessing the elements of a list or data.frame: [] and [[]]. What is the
57
votes
12
answers
2.6K
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How to unload a package without restarting R
I'd like to unload a package without having to restart R (mostly because restarting R as I try out differ
57
votes
8
answers
2.2K
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What is the difference between require() and library()?
What is the difference between require() and library()?
