Increasing the number of operations results in errors even in for statements with the same configured

Does anyone know why the third for statement is an error?

The code below is the complete code from creating each object to processing the for statement, and the output from the middle.

I think it's very simple, but I get an error in the third for statement with the same configuration.

If you know anyone, please let me know.

The environment is Windows 10.

Written code

av<-1:8#Create Each Vector
bv<-1:20
cv<-1:40

avm<-av%>%matrix(nrow=4)%>%as.data.frame()#Create Each Data Frame
bvm<-bv%>%matrix(nrow=4)%>%as.data.frame()
cvm<-cv%>%matrix(nrow=4)%>%as.data.frame()

name1<-letters [1:2]　　# preparation
name2<-letters [1:5]
name3<-letters [1:10]

colnames(avm)<-name1#Column name entry
colnames(bvm)<-name2
colnames(cvm)<-name3

avm;bvm;cvm#verify

for (i in 1:2) {
  a<-avm%>%filter(avm[i]<avm[4,i])%>%select(name1[i])
  a%>%print()
} 

for (i in 1:5) {
  a<-bvm%>%filter(bvm[i]<bvm[4,i])%>%select(name2[i])
  a%>%print()
} 

for (i in 1:10) {
  a<-cvm%>%filter(cvm[i]<cvm[4,i])%>%select(name3[i])
  a%>%print()
}

Output results (from the middle)

>avm;bvm;cvm#verify
  ab
1 1 5
2 2 6
3 3 7
4 4 8
  abcde
1 1 5  9 13 17
2 2 6 10 14 18
3 3 7 11 15 19
4 4 8 12 16 20
  abc de fghij
1 1 5  9 13 17 21 25 29 33 37
2 2 6 10 14 18 22 26 30 34 38
3 3 7 11 15 19 23 27 31 35 39
4 4 8 12 16 20 24 28 32 36 40

>for(i in 1:2){
   a<-avm%>%filter(avm[i]<avm[4,i])%>%select(name1[i])
   a%>%print()
 } 
  a
1 1
2 2
3 3
  B
1 5
2 6
3 7

>for(i in 1:5){
   a<-bvm%>%filter(bvm[i]<bvm[4,i])%>%select(name2[i])
   a%>%print()
 } 
  a
1 1
2 2
3 3
  B
1 5
2 6
3 7
   c
1  9
2 10
3 11
   d
1 13
2 14
3 15
   e
1 17
2 18
3 19

>for (i in 1:10) {
   a<-cvm%>%filter(cvm[i]<cvm[4,i])%>%select(name3[i])
   a%>%print()
 } 
 Error: Problem with `filter() `input`..1`.
iInput`..1`is`cvm[i]<cvm[4,i]`.
x undefined columns selected
Run`rlang::last_error()`to see where the error occurred.

2022-09-30 21:59

2 Answers

I think I should write it in the comment section because I'm a little careless about answering questions, but I can't do text shaping in the comment section, so I'll write it as an answer.

If you use tidyverse because you use %>%, you will no longer use index-only variables such as i, j, idx, etc., and you will not see the column name i.

First, select can also be a column index, so writing like name3(idx) is not necessary in the first place.

require(tidyverse)#The original code does not appear in the questionnaire, but it clearly has to be read before it works.
cvm<-data.frame(matrix(1:40,nrow=4)%>%setNames(letters[1:10])

for (idx in 1:10) filter(cvm, cvm[idx]<cvm[4,idx])%>%select(idx)%>%print()

For filter, you can also specify column indexes using cross or filter_at.

for(idx in 1:10)filter(cvm,across(idx,~.<.[4]))%>%select(idx)%>%print()

# However, filter_at is deprecated
for(idx in 1:10)filter_at(cvm,idx,~.<.[4])%>%select(idx)%>%print()

In addition, if you use map or walk instead of the for statement, this is what happens

walk (1:10, ~filter(cvm, across(.x, ~.<.[4]))%>%select(.x)%>%print)

2022-09-30 21:59

Thank you very much, everyone.

The solution was presented in the comments, so I will summarize the other details.
Here's a summary.

Problems this time:
The loop variable i was duplicated with the column name i of the specified data frame

solutions:
Changing the Loop Variable in the for Statement (from i to idx)

Resolved Output:

>for (idx in 1:10){
+   a<-cvm%>%filter(cvm[idx]<cvm[4,idx])%>%select(name3[idx])
+   a%>%print()
+ } 
  a
1 1
2 2
3 3
  B
1 5
2 6
3 7
   c
1  9
2 10
3 11
   d
1 13
2 14
3 15
   e
1 17
2 18
3 19
   f
1 21
2 22
3 23
   g
1 25
2 26
3 27
   h
1 29
2 30
3 31
   i
1 33
2 34
3 35
   j
1 37
2 38
3 39

2022-09-30 21:59

If you have any answers or tips

Popular Tags

python x 4647

android x 1593

java x 1494

javascript x 1427

c x 927

c++ x 878

ruby-on-rails x 696

php x 692

python3 x 685

html x 656