Question

我有一个这样的数据框：

df <- data.frame(size_upms = c(126, 123, 148),
             electric_mean = c(0.716756756756757,0.647859922178988, 0.726313694267516),
             gas_mean = c(0.273513513513513,0.322679266259033, 0.259554140127389),
             firewood_mean = c(0, 0.00111172873818788,0.00179140127388535))

# df
#  size_upms electric_mean  gas_mean firewood_mean
#1       126     0.7167568 0.2735135   0.000000000
#2       123     0.6478599 0.3226793   0.001111729
#3       148     0.7263137 0.2595541   0.001791401

我想使用mapply

为每行使用参数获取样本

l <- mapply(sample,c("electric","gas","firewood"),df$size_upms,TRUE,
            c(df$electric_mean,df$gas_mean,df$firewood_mean))

但是我收到了这个错误：

#Error in sample.int(length(x), size, replace, prob) : 
#  too few positive probabilities

但是，如果我将样本函数应用于每一行，它的工作原理如下：

sample(c("electric","gas","firewood"),df$size_upms[1],TRUE,
   c(df$electric_mean[1],df$gas_mean[1],df$firewood_mean[1]))[1:5]
#[1] "gas"      "electric" "electric" "gas"      "electric"
sample(c("electric","gas","firewood"),df$size_upms[2],TRUE,
   c(df$electric_mean[2],df$gas_mean[1],df$firewood_mean[2]))[1:5]
#[1] "electric" "gas"      "gas"      "gas"      "electric"
sample(c("electric","gas","firewood"),df$size_upms[3],TRUE,
   c(df$electric_mean[3],df$gas_mean[3],df$firewood_mean[1]))[1:5]
#[1] "electric" "electric" "gas"      "electric" "electric"

但我想使用mapply，因为我想将它应用于大数据帧

我做错了什么？

Answer 1

按行显示，使用apply或lapply更容易。 mapply或其他apply解决方案

之间的效果差别不大

lapply(seq_len(nrow(df)), function(i) 
    sample(c("electric","gas","firewood"), df$size_upms[i], TRUE, 
    unlist(c(df$electric_mean[i],df$gas_mean[i],df$firewood_mean[i]))))

OP解决方案中的错误是连接过程。在这里，我们将参数作为单独的列从数据集传递，然后在匿名函数调用中，进行连接。这将确保为每个步骤选择列中相应的行元素。

Map(function(x,y, u, w) sample(c("electric","gas","firewood"), x, 
     TRUE, c(y, u, w)), df$size_upms, df$electric_mean, df$gas_mean, df$firewood_mean)

或者@thelatemail评论说，我们可以使用do.call

来避免一些打字

do.call(Map, c( function(x,y, u, w) 
    sample(c("electric","gas","firewood"), x, TRUE, c(y,u,w)), unname(df)))

使用mapply创建样本时出错

1 个答案: