此问题与Stata: select the minimum of each observation有关。每组选择最低值
我有数据如下:
clear
input str4 id int eventdate byte dia_bp_copy int sys_bp_copy
"pat" 15698 100 140
"pat" 16183 80 120
"pat" 19226 98 155
"pat" 19375 80 130
"sue" 14296 80 120
"sue" 14334 88 127
"sue" 14334 96 158
"sue" 14334 84 136
"sue" 14403 86 124
"sue" 14403 88 134
"sue" 14403 90 156
"sue" 14403 86 134
"sue" 14403 90 124
"sue" 14431 80 120
"sue" 14431 80 140
"sue" 14431 80 130
"sue" 15456 80 130
"sue" 15501 80 120
"sue" 15596 80 120
"mary" 14998 90 154
"mary" 15165 91 179
"mary" 15280 91 156
"mary" 15386 81 154
"mary" 15952 77 133
"mary" 15952 80 144
"mary" 16390 91 159
end
有些人在一天多的读数,如见1999年3月31日苏我要选择每天的最低读数。
这里是我的代码,它让我有一些方法。它笨重笨拙,我正在寻求帮助,以更直接的方式做我想做的事情。
*make flag for repeat observations on same day
sort id eventdate
by id: gen flag =1 if eventdate==eventdate[_n-1]
by id: gen flag2=1 if eventdate==eventdate[_n+1]
by id: gen flag3 =1 if flag==1 | flag2==1
drop flag flag2
* group repeat observations together
egen group = group(id flag3 eventdate)
* find lowest `sys_bp_copy` value per group
bys group (eventdate flag3): egen low_sys=min(sys_bp_copy)
*remove the observations where the lowest value of `sys_bp`_copy doesn't exist
bys group: gen remove =1 if low_sys!=sys_bp_copy
drop if remove==1 & group !=.
****本在哪里,我想帮助**问题
上述方法的问题是,对苏,她的两个重复读数具有相同VAL sys_bp_copy
。所以我上面的方法留给她多个读数。
在这种情况下,我想参考dia_sys_copy
并选择最低值,以帮助我在每次读取一行时选择多行读数。代码如下 - 但必须有一个更简单的方法来做到这一点?
drop flag3 remove group
sort id eventdate
by id: gen flag =1 if eventdate==eventdate[_n-1]
by id: gen flag2=1 if eventdate==eventdate[_n+1]
by id: gen flag3 =1 if flag==1 | flag2==1
egen group = group(id flag3 eventdate)
bys group (eventdate flag3): egen low_dia=min(dia_bp_copy)
bys group: gen remove =1 if low_dia!=dia_bp_copy
drop if remove==1 & group !=.
好吧,我会进行编辑,以使更多succint。不挂断。 – user2363642