combn错误的含义：有趣的错误（X[[i]]，…）：n<；m在R

尝试创建一对元素，但出现以下错误：

Error in FUN(X[[i]], ...) : n < m

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谢谢你的帮助。谢谢。

这是元素数量少于“m”的情况之一。一个选项是为

list

的

length

创建一个小于'm'的异常

lapply(split(my$symbol, my$character), function(x)
          if(length(x)>1) {
            combn(x, 2, simplify=FALSE)
           }
           else x)

my:
symbol   character
BHMT    Abruptio Placentae
BHMT    Diabetes Mellitus, Type 2
BHMT    Lymphoma, Non-Hodgkin
BHMT    Neural Tube Defects
BID     Carcinoma, Hepatocellular
BID     Stomach Neoplasms
BIN1    Alzheimer Disease
BIN1    Myopathies, Structural, Congenital
BIN1    Myopathy, Centronuclear, Autosomal Recessive
BIRC5   Lung Neoplasms
BIRC5   Ovarian Neoplasms
BIRC5   Stomach Neoplasms
BIRC6   Neoplasms
BIRC7   Carcinoma, Renal Cell
BLK     Arthritis, Rheumatoid 
BLK     Lupus Erythematosus, Systemic
BLK     Maturity-onset diabetes of the young, type 11

lapply(split(my$symbol, my$character), function(x)
          if(length(x)>1) {
            combn(x, 2, simplify=FALSE)
           }
           else x)