在复杂数据帧中计算真/假

Question

我想在R中做一些相当复杂的事情,我不确定从哪里开始.

我有一个看起来像这样的数据框:

main_val sub_val bit_one bit_two
 one      a        1       1
 one      a        1       0
 one      a        1       1
 one      b        1       0
 two      a        1       1
 two      b        1       1
 two      a        1       1

现在我计算由每个主值的每个子值的位表示的0,1s,2和3的数量.所以这应该返回:

main_val sub_val  0s  1s  2s  3s
 one       a      0   0   1   2
 one       b      0   0   1   0
 two       a      0   0   0   2
 two       b      0   0   0   1

有什么想法怎么做？我只能想到永远需要的循环(这将在很多数据上运行).

Answer 1

原谅我先前的评论-我觉得你其实只需要table()和reshape()这样做的基础R.它可能很慢,如果你有一个真正庞大的数据量,然而,在这一点上,我建议调查data.table.

# Start by turning of stringsAsFactors
options(stringsAsFactors = FALSE)

# Create fake data
fake.data <- data.frame(main_val = c("one","one","one","one","two","two","two"),
                        sub_val = c("a","a","a","b","a","b","a"),
                        bit_one = c(1,1,1,1,1,1,1),
                        bit_two = c(1,0,1,0,1,1,1))

# Generate a decimal representation of your two bits
fake.data$decimal <- fake.data$bit_one*1 +fake.data$bit_two*2

# Create a table of the results, then reshape it
fake.data.summary <- as.data.frame(table(Main=fake.data$main_val,
                                         Sub=fake.data$sub_val,
                                         Value=fake.data$decimal))

fake.data.summary <- reshape(data = fake.data.summary,
                             v.names = "Freq",
                             idvar = c("Main","Sub"),
                             timevar = "Value",
                             direction = "wide")

请注意,在此示例中,输出中只有一个和三个,因为输入中只有一个和三个.如果需要统一输出,尽管可能存在或不存在,您可能需要对输出进行一些消毒 - 但我怀疑您不需要那样,因为您可能有足够的音量来确保表示0到3 .