Question

这是我第一次上堆。我试过寻找答案，但我似乎找不到任何相关的东西。我希望有人能帮帮忙。

我这里有一个数据框：每个科目做6次试验，有105个科目。

我想找到每个subj的6次试验的'skip'的平均值。

请有人给我一个关于如何开始的提示。

>     subj entropy n_gambles trial choice
1      0    high         2     0   skip
2      0    high         2     1   skip
3      0    high         2     2   skip
4      0    high         2     3   skip
5      0    high         2     4   skip
6      0    high         2     5   skip
7      1    high        32     0    buy
8      1    high        32     1    buy
9      1    high        32     2    buy
10     1    high        32     3    buy
11     1    high        32     4    buy
12     1    high        32     5    buy

Answer 1

您可以使用plyr包中的ddply :(您提到将有六个试验，因此通过将观察数量除以6来计算平均值，只选择=跳过每个主题）

library(plyr)
ddply(df,.(subj),summarise,mymean=(length(which(choice=="skip")))/6)
  subj mymean
1    0      1
2    1      0

注意：df是您的数据

Answer 2

如果我必须猜测，那么您打算为n_gambles的每个主题获得choice==skip的平均值，那么这可能会有效：

# Data
df<- read.table(text="subj  entropy n_gambles   trial   choice
0   high    2   0   skip
0   high    2   1   skip
0   high    2   2   skip
0   high    2   3   skip
0   high    2   4   skip
0   high    2   5   skip
1   high    32  0   buy
1   high    32  1   buy
1   high    32  2   buy
1   high    32  3   buy
1   high    32  4   buy
1   high    32  5   buy",header=T)

# Get mean
aggregate(df[df$choice == "skip","n_gambles"],
          list(subj=df[df$choice == "skip","subj"]),
          mean)

# Output
#  subj x
# 1 0 2

编辑：据我了解，您需要skip每subj的频率：试试这个：

# Get counts
result <- as.data.frame(table(df$subj,df$choice))
colnames(result) <- c("subj","choice","Freq")
# Subset for "skip" and divide by 6
result <- result[ result$choice == "skip",]
result$Freq <- result$Freq/6

计算R中每个受试者的试验平均值

2 个答案: