从两列中查找最大的一对，同时保持数据框完整

编程问答 2022-06-12

问题描述

我有一个数据框，我想根据两列查找最大的对。但是，当我对数据框进行分组时，其他列上的细微变化都会影响我的结果。

让我告诉你：

library(plyr)

usercsv_data <- data.frame(id_str = c("89797","12387231231","1234823432","3483487344","89797","1234823432"),screen_name = c("A","B","C","D","A","C"),location = c("FL","CO","NYC","MI","FL","NYC"),verified = c("Y","N","Y","Y"),created = c("Sun","Mon","Tue","Sun","Fri"),friends_count = c(1,2,5,787,7,5),followers_count= c(2,4,6,897,3))

#         id_str screen_name location verified created friends_count followers_count
# 1       89797           A       FL        Y     Sun             1               2
# 2 12387231231           B       CO        N     Mon             2               4
# 3  1234823432           C      NYC        N     Tue             5               6
# 4  3483487344           D       MI        Y     Sun           787             897
# 5       89797           A       FL        N     Tue             7               4
# 6  1234823432           C      NYC        Y     Fri             5               3


#This gets me the max pairs when the groups variable are unique
plyr::ddply(usercsv_data,.(id_str,screen_name),numcolwise(max))

#         id_str screen_name friends_count followers_count
# 1  1234823432           C             5               6
# 2 12387231231           B             2               4
# 3  3483487344           D           787             897
# 4       89797           A             7               4


#BUT,when I want to do same technique with whole dataframe,I get same dataframe
plyr::ddply(usercsv_data,screen_name,location,verified,created),numcolwise(max))

#         id_str screen_name location verified created friends_count followers_count
# 1  1234823432           C      NYC        N     Tue             5               6
# 2  1234823432           C      NYC        Y     Fri             5               3
# 3 12387231231           B       CO        N     Mon             2               4
# 4  3483487344           D       MI        Y     Sun           787             897
# 5       89797           A       FL        N     Tue             7               4
# 6       89797           A       FL        Y     Sun             1               2

但是我想要这样的东西-

#         id_str screen_name location verified created friends_count followers_count
# 1  1234823432           C      NYC        N     Tue             5               6
# 3 12387231231           B       CO        N     Mon             2               4
# 4  3483487344           D       MI        Y     Sun           787             897
# 5       89797           A       FL        N     Tue             7               4

如何分组以便维护所有列，但仅保留存在最大对的行？当前，当组变量更多时，它会保留唯一的变量（应该是这样），但由于知识不足，我也无法搜索问题。

解决方法

plyr已停用，因此我们可以在此处使用dplyr，方法是创建一个列，该列的总和为friends_count和followers_count，然后为每个{{ 1}}和id_str。

screen_name

或者不创建library(dplyr) usercsv_data %>% mutate(max = rowSums(select(.,friends_count,followers_count))) %>% group_by(id_str,screen_name) %>% slice(which.max(max)) 列。

max
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