Conditional sum between two data frames in R

Question

I have a data frame with dates and more information. I want to create a new data frame with just two columns: the unique dates and the amount of times they appear in the "main" dataframe. I've searched around but can't find anything, all the examples I find are limited to using data from the same dataframe.

lmo · Answer 1 · 2016-04-19T18:21:36.657

1

for dataframe df with date variable dates try

newdf <- as.data.frame(table(df$dates))
names(newdf) <- c("dates", "counts")

edited Apr 19 '16 at 18:21

answered Apr 19 '16 at 15:49

lmo

37,904
9
56
69

1

Thanks for the catch @Frank. – lmo Apr 19 '16 at 18:22

score 1 · Answer 2 · answered Apr 19 '16 at 16:09

1

Try this:

#creates a test df
employee <- c('A','B','C')
startdate <- as.Date(c('2010-11-1','2008-3-25','2008-3-25'))
employDF <- data.frame(employee,  startdate)

# creates new df base on startdate column and count freq
testDF <- data.frame(table(employDF$startdate))
# changes the column names
names(testDF) <- c("startdate", "counts")
# prints out
testDF

answered Apr 19 '16 at 16:09

NangSaigon

1,253
12
14

how is this different from the other answer? – Jaap Apr 19 '16 at 18:50
see the edits, time of update, you will see which one provide the correct one first – NangSaigon Apr 20 '16 at 02:12

Conditional sum between two data frames in R

2 Answers2