Re: [問題] 指定group

[celestialgod (天)]

我不知道這樣有沒有快多少... 參考看看

library(data.table)  # setnames
library(plyr)        # dlply, laply, mapvalues
library(dplyr)       # mutate, summarise, group_by
library(magrittr)    # %>%, %$%

dt <- data.table(
  series = c(1,2,3,4,5,6,1,1,2,2,2,2,2),
  cate = c(2,3,4,2,2,5,1,2,2,3,4,4,4)
)

## method 1 (應該會較慢，而且程式比較醜)
maptable = dlply(dt, .(series), table) %>% laply(function(x){
  as.integer(colnames(x)[which.max(x)])
}) %>% cbind(as.integer(names(.)), .)
dt2 = dt %>% mutate(cate = mapvalues(series, maptable[,1], maptable[,2]))

## method 2
-maptable = dt %>% group_by(series, cate) %>% summarise(n()) %>%
  group_by(series) %>% summarise(maxCate = max(cate))
dt2 = dt %>% mutate(cate = mapvalues(series, maptable$series,
  maptable$maxCate))

## 把上面連在一起的版本 (沒有maptable這個暫存變數)
dt2 = dt %>% group_by(series, cate) %>% summarise(n()) %>%
  group_by(series) %>% summarise(maxCate = max(cate)) %>%
  setnames("series", "maxSeries") %$%
  mutate(dt, cate = mapvalues(series, maxSeries, maxCate))

: 例如
:       series cate
:  [1,]      1    2
:  [2,]      2    3
:  [3,]      3    4
:  [4,]      4    2
:  [5,]      5    2
:  [6,]      6    5
:  [7,]      1    1
:  [8,]      1    2
:  [9,]      2    2
: [10,]      2    3
: [11,]      2    4
: [12,]      2    4
: [13,]      2    4
: 在series中1出現三次,其cate分別為2,2,1   頻率最高的為2
: 想將所有series為1的族群   其cate欄位接指定為2
: 又例如 series中為2的族群  其cate 分別為 3,2,3,4,4,4 頻率最高的4
: 想將所有series為2的族群 其cate欄位皆指定為4
: 請問除了用for loop外有其他方法嗎?

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推 lambking: 謝謝你! 有快很多
→ lambking: 另外想請問如果是series中有missing data
→ lambking: 能針對missing data 保留其原本cate 值嗎
在maptable產生之後加上na.omit，然後加上控制項去控制NA不要覆蓋到原本的cate就好

PS: na.omit是把有包含NA的那一個ROW移除，是base的函數

dt <- data.table(
  series = c(1,2,3,4,5,6,1,1,2,2,2,2,2,NA,NA,NA),
  cate = c(2,3,4,2,2,5,1,2,2,3,4,4,4,3,3,1)
)
dt2 = dt %>% group_by(series, cate) %>% summarise(n()) %>%
  group_by(series) %>% summarise(maxCate = max(cate)) %>%
  setnames("series", "maxSeries") %>% na.omit %$%
  mutate(dt, cate = ifelse(is.na(series), cate,
    mapvalues(series, maxSeries, maxCate)))
#    series cate
# 1:      1    2
# 2:      2    4
# 3:      3    4
# 4:      4    2
# 5:      5    2
# 6:      6    5
# 7:      1    2
# 8:      1    2
# 9:      2    4
#10:      2    4
#11:      2    4
#12:      2    4
#13:      2    4
#14:     NA    3
#15:     NA    3
#16:     NA    1

推 lambking: 謝謝! 了解了!
→ lambking: 但在實際執行時 會出現以下錯誤訊息
→ lambking: Error in n() : This function should not be called
→ lambking: directly
→ lambking: 查到是因為plyr 和dplyr皆有summarise功能
我的版本沒問題

你可以指定dplyr:::summarise

推 lambking: 謝謝, 但改完之後反而出現setnames的問題
→ lambking: Error in setnames(., "series", "maxSeries") :
→ lambking: Items of 'old' not found in column names: series
→ lambking: 請問你用的是哪一個版本呢? 謝謝
我都沒有問題...

我用的R: Revolution R Open 3.2.0

我的session information:

> sessionInfo()
R version 3.2.0 (2015-04-16)
Platform: x86_64-w64-mingw32/x64 (64-bit)
Running under: Windows 7 x64 (build 7601) Service Pack 1

locale:
[1] LC_COLLATE=Chinese (Traditional)_Taiwan.950
[2] LC_CTYPE=Chinese (Traditional)_Taiwan.950
[3] LC_MONETARY=Chinese (Traditional)_Taiwan.950
[4] LC_NUMERIC=C
[5] LC_TIME=Chinese (Traditional)_Taiwan.950

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base

other attached packages:
[1] magrittr_1.5     dplyr_0.4.2      plyr_1.8.3       data.table_1.9.4

loaded via a namespace (and not attached):
 [1] lazyeval_0.1.10 R6_2.0.1        assertthat_0.1  parallel_3.2.0
 [5] DBI_0.3.1       tools_3.2.0     reshape2_1.4.1  Rcpp_0.12.0
 [9] stringi_0.4-1   stringr_1.0.0   chron_2.3-45

推 lambking: 謝謝  我再試試看
→ lambking: 另外想請問如果series 和 cate 都是 character
這個應該不用改太多，你自己改一下就好了
※ 編輯: celestialgod (123.205.27.107), 08/17/2015 09:23:53