Question

我的数据框如下所示：

      var1      var2    var3
1     0         5       "other"
2     25        3       "sample"
3     4         5       "other"
4     60        5       "other"
5     4         5       "other"
6     60        5       "other"
7     25        3       "sample"
8     4         8       "other"
9     60        7       "other"
10    4         3       "other"  
11    25        27      "sample"  
12    4         9       "other"   
13    30        4       "other"

我想添加一列，对于等于var3 = =“sample”的所有行，我们计算var2列中的值减去“sample”行下面的行的var 2列中的值。这看起来像这样：

      var1      var2    var3      var4
1     0         5       "other"   NA
2     25        25      "sample"  20
3     4         5       "other"   NA
4     60        5       "other"   NA
5     4         5       "other"   NA
6     60        5       "other"   NA
7     25        13      "sample"  8
8     4         5       "other"   NA
9     60        5       "other"   NA
10    4         3       "other"   NA
11    25        27      "sample"  18
12    4         9       "other"   NA
13    30        4       "other"   NA

我试过了

if(df$var3=="sample") {df$var4<-(df$var2-df$var2[+1,])}

但这显然不起作用。如何使用特定行中的列及其下方的确切行进行计算？

Answer 1

我们可以减去def delete_projection(): with open('projections.txt') as projections: #projections = open('users.txt', 'r').readlines() delete = input("Input projection code you want to delete: ") for i in projections: projection = i.strip("\n").split("|") if delete == projection[0]: projection[8]="false" #projections.close() with open('projections.txt', 'w+') as projections: projections.write("false") projections.close()，即＆＃39; var2＆＃39;的下一个元素。当＆＃39; var3＆＃39;是＆＃39;样本＆＃39;

lead

数据

library(dplyr)
df1 %>%
     mutate(var4 = ifelse(var3 == "sample", var2 -lead(var2), NA))

如何选择（并进行计算）行和它下面的行

1 个答案:

数据