小编dil*_*iop的帖子

我想知道是否可以有一个可选的数组.让我们假设一个这样的架构:

{ 
    "type": "record",
    "name": "test_avro",
    "fields" : [
        {"name": "test_field_1", "type": "long"},
        {"name": "subrecord", "type": [{
         "type": "record",
         "name": "subrecord_type",
           "fields":[{"name":"field_1", "type":"long"}]
          },"null"]
    },
    {"name": "simple_array",
    "type":{
        "type": "array",
        "items": "string"
      }
    }
  ]
}

尝试编写没有"simple_array"的avro记录会导致数据编写器中的NPE.对于subrecord,它很好,但是当我尝试将数组定义为可选时:

{"name": "simple_array",
 "type":[{
   "type": "array",
   "items": "string"
   }, "null"]

它不会导致NPE,但会导致运行时异常:

AvroRuntimeException: Not an array schema: [{"type":"array","items":"string"},"null"]

谢谢.

我有一个相当大的数据框,我需要一个好的方法(下面解释)来提取在某一组标签内具有给定字段的最大值的行的索引.为了更好地解释这一点,这里是一个示例10行数据帧:

      value label
1  5.531637     D
2  5.826498     A
3  8.866210     A
4  1.387978     C
5  8.128505     C
6  7.391311     B
7  1.829392     A
8  4.373273     D
9  7.380244     A
10 6.157304     D

生成:

structure(list(value = c(5.531637, 5.826498, 8.86621, 1.387978, 8.128505, 
7.391311, 1.829392, 4.373273, 7.380244, 6.157304), 
label = c("D", "A", "A", "C", "C", "B", "A", "D", "A", "D")), 
.Names = c("value", "label"), class = "data.frame", row.names = c(NA, -10L))

如果我想知道每个标签具有最大值的行的索引是什么,我目前使用以下代码:

idx <- sapply(split(1:nrow(d), d$label), function(x) {
  x[which.max(d[x,"value"])]
})

生成这个答案:

A …

是否有可能在Dummyvariables模型中检查多重共线性？假设以下示例

treatment <- factor(rep(c(1, 2), c(43, 41)), levels = c(1, 2), labels = c("placebo", "treated"))
improved <- factor(rep(c(1, 2, 3, 1, 2, 3), c(29, 7, 7, 13, 7, 21)), levels = c(1, 2, 3), labels = c("none", "some", "marked"))
numberofdrugs <- rpois(84, 5)+1
healthvalue <- rpois(84,5)
y <- data.frame(healthvalue,numberofdrugs, treatment, improved)

test <- lm(healthvalue~numberofdrugs+treatment+improved, y)

当我想检查这种模型中是否存在多重共线性时,我该怎么做？