Re: [程式] 關於R 統計點的數目

看板Statistics作者celestialgod時間10年前 (2015/12/31 01:31)推噓3(3推 0噓 4→)

留言7則, 1人參與討論串2/2 (看更多)

※ 引述《jackhzt (巴克球)》之銘言： : [軟體程式類別]:R : [程式問題]:資料處理 : [程式熟悉]:熟悉 : [問題敘述]:假設我有一筆資料(x1,y1),(x2,y2),(x3,y3)...我將其用plot打點 : 如今想對其所在的座標做分割，切出4個等面積的區域， : 請問有相關的程式碼可以統計區域內點的總數目嗎? : [程式範例]: : EX: : x=rnorm(10,0,1) : y=rnorm(10,2,1) : z=data.frame(x,y) : plot(z) #打點出來 : 假設現在想對x軸=0以及y軸=0 分四塊， : 那有方法可以統計這4塊面積中點的數目嗎? : 目前我的方法就是把點拿出來先對x軸比大小再對y軸比大小 : 但是如果比數或是需要分割的東西太多，就會很複雜，有其他較好的方法嗎? 1. 如果會dplyr library(dplyr) library(magrittr) set.seed(2) x=rnorm(10,0,1) y=rnorm(10,1,1) z=data.frame(x,y) a = 0; b = 0 z_append = z %>% mutate(x_gt_a = x > a, y_gt_b = y > b) %>% group_by(x_gt_a, y_gt_b) %>% summarise(count = length(x)) # # Source: local data frame [4 x 3] # Groups: x_gt_a y_gt_b # # x_gt_a y_gt_b count # (lgl) (lgl) (int) # 1 FALSE FALSE 1 # 2 FALSE TRUE 4 # 3 TRUE FALSE 1 # 4 TRUE TRUE 4 # 多個切割點就看第三點吧 2. 如果不會dplyr mat = tapply(rep(1, nrow(z)), list(z$x > a, z$y > b), length) z_count = data.frame(x_gt_a = rep(colnames(mat), 2), y_gt_b = rep(rownames(mat), each = 2), count = as.vector(mat)) # x_gt_a y_gt_b count # 1 FALSE FALSE 1 # 2 TRUE FALSE 1 # 3 FALSE TRUE 4 # 4 TRUE TRUE 4 3. findInterval library(dplyr) library(magrittr) set.seed(2) x=rnorm(1000,0,1) y=rnorm(1000,1,1) z=data.frame(x = x, y = y) x_cutPoints = c(-Inf, seq(-1, 1, by = 0.1), Inf) y_cutPoints = c(-Inf, seq(-1, 1, by = 0.1), Inf) count_df = z %>% mutate(cutPointsGroup_x = cut(x, x_cutPoints), cutPointsGroup_y = cut(y, y_cutPoints)) %>% group_by(cutPointsGroup_x, cutPointsGroup_y) %>% summarise(count = length(x)) # # Source: local data frame [276 x 3] # Groups: cutPointsGroup_x, cutPointsGroup_y # # cutPointsGroup_x cutPointsGroup_y count # (fctr) (fctr) (int) # 1 (-Inf,-1] (-Inf,-1] 3 # 2 (-Inf,-1] (-1,-0.9] 2 # 3 (-Inf,-1] (-0.8,-0.7] 1 # 4 (-Inf,-1] (-0.7,-0.6] 4 # 5 (-Inf,-1] (-0.6,-0.5] 2 # 6 (-Inf,-1] (-0.5,-0.4] 2 # 7 (-Inf,-1] (-0.4,-0.3] 4 # 8 (-Inf,-1] (-0.3,-0.2] 2 # 9 (-Inf,-1] (-0.2,-0.1] 2 # 10 (-Inf,-1] (-0.1,0] 6 # .. ... ... ... -- R資料整理套件系列文： magrittr #1LhSWhpH (R_Language) http://tinyurl.com/1LhSWhpH data.table #1LhW7Tvj (R_Language) http://tinyurl.com/1LhW7Tvj dplyr(上) #1LhpJCfB (R_Language) http://tinyurl.com/1LhpJCfB dplyr(下) #1Lhw8b-s (R_Language) tidyr #1Liqls1R (R_Language) http://tinyurl.com/1Liqls1R -- ※ 發信站: 批踢踢實業坊(ptt.cc), 來自: 140.109.73.231 ※ 文章網址: https://www.ptt.cc/bbs/Statistics/M.1451496691.A.D63.html

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jackhzt

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