[R] How to plot a histogram of weekday frequencies in a list of dates?

[Wu Gong]

Hope it works.

## Create a sample of dates 
dates <- sample(seq(ISOdate(2009,1,1), ISOdate(2009,12,31), "hour"),1000)

## Create 14 labels for barplot("Mon AM","Mon PM",etc.)
labels <- format(seq(ISOdate(2010,7,11,5), ISOdate(2010,7,18,4), "12
hours"),"%a %p")

## Use table function to calculate the frequency of each time intervel
## Use format "%w %p" to get the weekday name and AM/PM indicator of the
dates
## Minus 12*60*60 seconds to change AM interval from 0-12AM to 7AM-7PM
barplot(table(format((dates-12*60*60), "%w %p")),names.arg=labels)


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