以字符串形式读取数字 [英] Reading numbers as strings

问题描述

我是R编程的新手，我想在R中读取文本文件.

I am new at R programming and I want to read a text file in R.

其中一列，可以说第7列是数字，并且每个数字都代表一个ID，我希望R像将它们当作字符串一样读取它们.并计算每个ID在文件中出现的次数(这样以后我就可以将每个ID的频率分配给给定的ID，以供以后使用) 我尝试过

One of the columns, lets say column 7 is numeric and each number represent an ID I want R to read the numbers as if they were strings. And count the number of times each ID appear in the file (such that later I can assign the frequency of each ID to the given ID for latter use) I have tried

mydata<-(read.table(filename.txt))
ID=mydata[7]
freq=table(ID)

此方法有效，但是将ID作为数字.现在我尝试了

This works but it takes the IDs as numbers. Now I have tried

freq=table(as.character(ID))

但是随后它将整个列ID仅作为一个字符串，并且来自

But then it takes the whole column ID as only one string and from

summary(freq)

我知道

Number of cases in table: 1 
Number of factors: 1 

推荐答案

从文本文件将数据读取到数据框中时，可以使用colClasses参数指定每列的类型.请参阅下面的文件，我的计算机中有此文件:

At the time of reading the data into your data frame from the text file you can specify the type of each column using the colClasses argument. See below a file have in my computer:

> head(read.csv("R/Data/ZipcodeCount.csv"))
    X zipcode stateabb countyno  countyname
1   1     401       NY      119 WESTCHESTER
2 391     501       NY      103     SUFFOLK
3 392     544       NY      103     SUFFOLK
4 393     601       PR        1    ADJUNTAS
5 630     602       PR        3      AGUADA
6 957     603       PR        5   AGUADILLA
> head(read.csv("R/Data/ZipcodeCount.csv",colClasses=c(rep("factor",5))))
    X zipcode stateabb countyno  countyname
1   1   00401       NY      119 WESTCHESTER
2 391   00501       NY      103     SUFFOLK
3 392   00544       NY      103     SUFFOLK
4 393   00601       PR      001    ADJUNTAS
5 630   00602       PR      003      AGUADA
6 957   00603       PR      005   AGUADILLA

> zip<-read.csv("R/Data/ZipcodeCount.csv",colClasses=c(rep("factor",5)))
> str(zip)
'data.frame':   53424 obs. of  5 variables:
 $ X         : Factor w/ 53424 levels "1","10000081",..: 1 36316 36333 36346 43638 52311 19581 23775 26481 26858 ...
 $ zipcode   : Factor w/ 41174 levels "00401","00501",..: 1 2 3 4 5 6 6 7 8 9 ...
 $ stateabb  : Factor w/ 60 levels "","  ","AK","AL",..: 41 41 41 46 46 46 46 46 46 46 ...
 $ countyno  : Factor w/ 380 levels "","000","001",..: 106 95 95 3 5 7 5 7 7 9 ...
 $ countyname: Factor w/ 1925 levels "","ABBEVILLE",..: 1844 1662 1662 9 10 11 10 11 11 12 ...
> head(table(zip[,"zipcode"]))

00401 00501 00544 00601 00602 00603 
    1     1     1     1     1     2 

如您所见，R不再将邮政编码视为数字，而是作为因素.在您的情况下，您需要指定前6列的类，然后选择factor作为第七列.因此，如果前6列为数字，则应为colClasses = c(rep("numeric",6),"factor").

as you can see R is no longer treating zipcodes as numbers but as factors. In your case you need to specify the class of the first 6 columns and then choose factor as your seventh. So if the first 6 columns are numeric it should be something like this colClasses = c(rep("numeric",6),"factor").

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