[R] about change columns for specific rows

[ruipbarradas at sapo.pt]

Hello,

Try

df[df$date >= '2012-01-01'& df$date <= '2013-12-31']$A = etc

Hope this helps,

Rui Barradas
 

Citando lily li <chocold12 at gmail.com>:

> Hi R users,
>
> I have a data frame, and I generate a date column like this:
> df$date = seq(as.Date('2012-01-01'), as.Date('2014-12-31'))
>
> df
> A  B  C
> 1  2   1
> 2  2   3
> 3  2   4
>
> So the data frame has 4 columns now. But when I want to change the values
> of column A for specific dates, such as 2012-01-01 to 2013-12-31, I use the
> code below:
> df[date >= '2012-01-01'&date <= '2013-12-31']$A =
> df[date >= '2012-01-01'&date <= '2013-12-31']$A +2
>
> But it does not work, the date I generate seems not effective. What is the
> problem? Thanks for your help.
>
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>
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