R，使用for循环，如何根据不同的目标数据框生成具有不同结果的新变量

Question

R, using for loop, how can I generate new variables with different results according to the different targeted data frame.

For example, I have data-frames named as Version1, version2, version3,version4, version5,version6.

For detail in versions:

Version1:
Name Age HW_score Midterm Final Gender Year_in_school
AA 21 90 90 90 F 1
AB 20 80 88 100 F 1
AC 22 85 95 97 M 1
AD 21 88 99 96 M 1

Version2:
Name Age HW_score Midterm Final Gender Year_in_school
AE 23 90 70 90 F 1
BB 20 84 88 90 M 1
DC 21 85 90 97 M 1
AD 22 88 94 96 M 2

Version3:
Name Age HW_score Midterm Final Gender Year_in_school
AZ 23 90 70 94 F 2
CB 20 89 88 90 M 3
FC 21 78 90 97 F 1
AA 24 89 96 96 M 2

similar for version4,5,6

If I have to select the row where the age is 21.

Q1: How can I create variables named as result_[the name of the data frame]: result_version1, result_version2, result_version3, result_version4,result_version5,result_version6. And store the results of each data frame into the new variables.

The desired results are

result_version1:
Name Age HW_score Midterm Final Gender Year_in_school
AA 21 90 90 90 F 1
AD 21 88 99 96 M 1

result_version2:
Name Age HW_score Midterm Final Gender Year_in_school
DC 21 85 90 97 M 1

result_version3:
FC 21 78 90 97 F 1

similar for result_version4,5,6

Q2: What if storing results from different data frame into one variable:

Desired output:

result_version_all
Name Age HW_score Midterm Final Gender Year_in_school
AA 21 90 90 90 F 1
AD 21 88 99 96 M 1
DC 21 85 90 97 M 1
FC 21 78 90 97 F 1

How should write the code in R using for loop to have the above output? Thanks!!!

Answer 1

You can put all the dataframes in a list and subset them using lapply .

result <- lapply(mget(paste0('Version', 1:6)), function(x) subset(x, Age == 21))

result has list of dataframes with output. To get them as separate dataframes use list2env

names(result) <- paste0('result_',paste0('Version', 1:6))
list2env(result, .GlobalEnv)

Combine all the list of dataframes into one result.

result_version_all <- do.call(rbind, result)

Answer 2

You could use the following code, it does not involve a for loop though.

Q1 result_version1 = Version1[which(Version1$Age == 21),] # repeat for all versions

Q2 result_version_all = rbind(result_version1,result_version2,...result_version6)