如何在R中切换行? [英] How to switch rows in R?

问题描述

我有一个包含以下内容的数组:

I have a array with following content:

> head(MEAN)
1901DJF     1901JJA     1901MAM     1901SON     1902DJF     1902JJA 
-0.45451556 -0.72922229 -0.17669396 -1.12095590 -0.86523850 -0.04031273 

这应该是一个时间序列，其季节性平均值为1901年至2009年.问题是所生成的列标题严格按字母顺序排列.但是，就季节而言，这没有多大意义，例如JJA(6月，7月，8月)领导MAM(3月，4月，5月).

This should be a time series with seasonal mean values from 1901 to 2009. The problem is that the generated column heads are strictly alphabetically ordered. However, in terms of season this doesn't make to much sense, e.g. JJA (june, july, august) is leading MAM (march, april, may).

如何切换阵列的每个MAM和JJA条目?

How could I switch each MAM and JJA entry of the array?

PS:在数据上轻触地生成MEAN.帧pdsi

PS: MEAN is generated applying tapply on the data.frame pdsi

> head(pdsi)
    date      scPDSI month seas seasyear
1 1901-01-01 -0.10881074   Jan  DJF  1901DJF
2 1901-02-01 -0.22287750   Feb  DJF  1901DJF
3 1901-03-01 -0.12233192   Mär  MAM  1901MAM
4 1901-04-01 -0.04440915   Apr  MAM  1901MAM
5 1901-05-01 -0.36334082   Mai  MAM  1901MAM
6 1901-06-01 -0.52079030   Jun  JJA  1901JJA
>
> MEAN <- tapply(pdsi$scPDSI, ts.pdsi$seasyear, mean, na.rm = T)

也许还有一种更优雅的方法来计算季节性平均值...

May be there is also known a more elegant way to calculate seasonal means...

推荐答案

您可以更改因子水平的顺序:

You can change the order of the factor levels:

pdsi[["seasyear"]] = factor(pdsi[["seasyear"]], levels = c("1901DJF", "1901MAM", etc))

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