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私は通貨記号のリストを持っていますが、それらはペアとして一緒に使用され、それ自体に反対することはできません。以下に例を示します。

ccy <- c("USD","EUR","JPY","GBP","CAD","AUD","NZD","CHF","NOK","SEK")
g <- expand.grid(ccy,ccy)
g <- g[g[,1]!=g[,2],]

ただし、USD vs EUR は EUR vs USD の逆数、または EUR vs JPY は JPY vs EUR の逆数なので、data.frame.

リストから一意のペアのみを取得するプログラム的な方法はありますか?

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使用combn():

combn(ccy, 2)
     [,1]  [,2]  [,3]  [,4]  [,5]  [,6]  [,7]  [,8]  [,9]  [,10] [,11] [,12] [,13] [,14] [,15] [,16]
[1,] "USD" "USD" "USD" "USD" "USD" "USD" "USD" "USD" "USD" "EUR" "EUR" "EUR" "EUR" "EUR" "EUR" "EUR"
[2,] "EUR" "JPY" "GBP" "CAD" "AUD" "NZD" "CHF" "NOK" "SEK" "JPY" "GBP" "CAD" "AUD" "NZD" "CHF" "NOK"
     [,17] [,18] [,19] [,20] [,21] [,22] [,23] [,24] [,25] [,26] [,27] [,28] [,29] [,30] [,31] [,32]
[1,] "EUR" "JPY" "JPY" "JPY" "JPY" "JPY" "JPY" "JPY" "GBP" "GBP" "GBP" "GBP" "GBP" "GBP" "CAD" "CAD"
[2,] "SEK" "GBP" "CAD" "AUD" "NZD" "CHF" "NOK" "SEK" "CAD" "AUD" "NZD" "CHF" "NOK" "SEK" "AUD" "NZD"
     [,33] [,34] [,35] [,36] [,37] [,38] [,39] [,40] [,41] [,42] [,43] [,44] [,45]
[1,] "CAD" "CAD" "CAD" "AUD" "AUD" "AUD" "AUD" "NZD" "NZD" "NZD" "CHF" "CHF" "NOK"
[2,] "CHF" "NOK" "SEK" "NZD" "CHF" "NOK" "SEK" "CHF" "NOK" "SEK" "NOK" "SEK" "SEK"

この関数は、入力ベクトルからcombn長さの一意の組み合わせをすべて生成します。n

詳細については、を参照してください?combn。

于 2013-03-05T13:44:34.470 に答える