blocks|key|4508206|text|read.csv期望只读取一个文件，所以您需要循环遍历文件，一种R惯用的方法是使用sapply：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|4508207|nrows+<-+sapply(+csvfile,+function(f)+nrow(read.csv(f))+)
sum(nrows)|code-block|syntax|javascript|4508208|例如，以下是complete函数的重写：|4508209|complete+<-+function(directory,id+=+1:332)+{
++++csvfiles+<-+sprintf("/Users/gcameron/Desktop/%25s/%2503d.csv",+directory,+id)
++++nrows+<-+sapply(+csvfiles,+function(f)+nrow(read.csv(f))+)
++++sum(nrows)
}|4508210|entityMap^0|0|8|15|6|0|0|6|8|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@$9|R|A|S|B|C]|$9|T|A|U|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|V|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|W|8|@$9|X|A|Y|B|C]]|D|@]|E|$]]|$1|M|3|N|5|H|7|Z|8|@]|D|@]|E|$I|J]]|$1|O|3|-4|5|6|7|10|8|@]|D|@]|E|$]]]|P|$]]

<code>read.csv</code> expects to read just one file, so you need to loop over files, a R idiomatic way of doing so is to use <code>sapply</code>: 

<pre><code>nrows &lt;- sapply( csvfile, function(f) nrow(read.csv(f)) )
sum(nrows)
</code></pre>

For example, here is a rewrite of your <code>complete</code> function:

<pre><code>complete &lt;- function(directory,id = 1:332) {
 csvfiles &lt;- sprintf("/Users/gcameron/Desktop/%s/%03d.csv", directory, id)
 nrows &lt;- sapply( csvfiles, function(f) nrow(read.csv(f)) )
 sum(nrows)
}
</code></pre>

blocks|key|4990837|text|家庭作业问题通常是这样标记的，尽管我不知道这是否是必需的，但这显然是家庭作业。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4990838|您编写的函数期望id不是向量(尽管默认值是整数的向量)。|4990839|将其更改为使用*apply函数之一(更简洁、更常见)，或者甚至使用显式循环。对于id向量中的每个元素，必须调用一个函数来打开该文件并计算观测值。|4990840|This+stackoverflow+post很好地解释了*apply函数之间的差异。|offset|length|4990841|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/questions/3505701/r-grouping-functions-sapply-vs-lapply-vs-apply-vs-tapply-vs-by-vs-aggrega^0|0|0|0|0|N|0|0^^$0|@$1|2|3|4|5|6|7|R|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|S|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|T|8|@]|9|@]|A|$]]|$1|F|3|G|5|6|7|U|8|@]|9|@$H|V|I|W|1|X]]|A|$]]|$1|J|3|-4|5|6|7|Y|8|@]|9|@]|A|$]]]|K|$L|$5|M|N|O|A|$P|Q]]]]

Homework problems usually get tagged as such, though I don't know if that is required, but this clearly is homework.

Your function as written expects that id is not a vector (despite the default value being a vector of integers).

Change it to either use one of the *apply functions (more concise and common), or even an explicit loop. For each element in the id vector, you must call a function that opens that file and counts the observations.

<a href="https://stackoverflow.com/questions/3505701/r-grouping-functions-sapply-vs-lapply-vs-apply-vs-tapply-vs-by-vs-aggrega">This stackoverflow post</a> has a good explanation of the differences between the *apply functions.

blocks|key|1158522|text|id+<-c(1:332)
filenames=list.files(path="source_path",+full.names=TRUE)

for(a+in+id){

++++dataset+<-+read.csv(filenames[a])

++++res+<-+nrow(na.exclude(dataset))++#nrow+count+the+row+of+the+dataset
++++
++++df+<-data.frame(
++++id+=a,
++++nobs+=res,++
++++stringsAsFactors=FALSE)
}+++

df|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1158523|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>id &lt;-c(1:332)
filenames=list.files(path=&quot;source_path&quot;, full.names=TRUE)

for(a in id){

 dataset &lt;- read.csv(filenames[a])

 res &lt;- nrow(na.exclude(dataset)) #nrow count the row of the dataset
 
 df &lt;-data.frame(
 id =a,
 nobs =res, 
 stringsAsFactors=FALSE)
} 

df
</code></pre>

blocks|key|343360|text|complete+<-+function(directory,+id+=+1:332){
++mylist+<-+list.files(path+=+directory,+pattern+=+".csv")
++result+<-+data.frame()
++for(i+in+id){
++++my_data+<-+read.csv(paste(directory,mylist[i],sep=""))
++++res+<-+nrow(na.exclude(my_data))++#nrow+count+the+row+of+the+dataset
++++df+<-+data.frame("id"+=+i,"nobs"+=+res,++stringsAsFactors=FALSE)
++++result+<-+rbind(result,df)
++}
++return(result)
}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|343361|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>complete &lt;- function(directory, id = 1:332){
 mylist &lt;- list.files(path = directory, pattern = &quot;.csv&quot;)
 result &lt;- data.frame()
 for(i in id){
 my_data &lt;- read.csv(paste(directory,mylist[i],sep=&quot;&quot;))
 res &lt;- nrow(na.exclude(my_data)) #nrow count the row of the dataset
 df &lt;- data.frame(&quot;id&quot; = i,&quot;nobs&quot; = res, stringsAsFactors=FALSE)
 result &lt;- rbind(result,df)
 }
 return(result)
}
</code></pre>

I'm working through an R tutorial and suspect that I have to use one of these functions but I'm not sure which (Yes I researched them but until I become more fluent in R terminology they are quite confusing).

In my working directory there is a folder "specdata". Specdata contains hundreds of CSV files named 001.csv - 300.csv.

The function I am working on must count the total number of rows for an inputed number of csv files. So if the argument in the function is <code>1:10</code> and each of those files has ten rows, return 100.

Here's what I have so far:

<pre><code>complete &lt;- function(directory,id = 1:332) {
 setpath &lt;- paste("/Users/gcameron/Desktop",directory,sep="/")
 setwd(setpath)
 csvfile &lt;- sprintf("%03d.csv", id)
 file &lt;- read.csv(csvfile)
 nrow(file)
 }
</code></pre>

This works when the ID argument is one number, say 17. But, if I input say 10:50 as an argument, I receive an error:

<pre><code>Error in file(file, "rt") : invalid 'description' argument
</code></pre>

What should I do to be able to count the total number of rows from the inputed ID parameter?

Counting the number of rows of a series of csv files

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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我正在学习一个R教程，我怀疑我必须使用这些函数中的一个，但我不确定是哪个(是的，我研究过它们，但在我对R术语变得更加流利之前，它们是相当令人困惑的)。在我的工作目录中有一个文件夹"specdata“。Specdata包含数百个名为001.csv - 300.csv的CSV文件。我正在使用的函数必须计算输入数量的csv文...

问计算一系列csv文件的行数
EN

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