I am trying to do Hartigan's diptest in R, however, I get the following error: 'x' must be numeric.
Apologies for such a basic question, but how do I ensure that the data that I load is numeric?
If I make up a set of values as follows (code below), the diptest works without problems:
library(diptest)
x = c(1,2,3,4,4,4,4,4,4,4,5,6,7,8,9,9,9,9,9,9,9,9,9)
hist(x)
dip.test(x)
But for example, when the same values are saved in an Excel file/tab delimited .txt file (saved as one column of values), and imported into R, when I run the diptest the 'x' must be numeric error occurs.
x <- read.csv("x.csv") # comes back in as a data frame
hist(x)
dip.test(x)
Is there a way to check what format the imported data from an Excel/.txt file is in R, and subsequently change it to be numeric? Thanks again.
Any help will be much appreciated thank you.
Here's what's happening. If you run the code that you know works, it's working because the data class is numeric as it should be. When you read it back in it's a data.frame, however. So you need to point to the numeric element of the data.frame:
library(diptest)
x = c(1,2,3,4,4,4,4,4,4,4,5,6,7,8,9,9,9,9,9,9,9,9,9)
write.csv(x, "x.csv", row.names=F)
x <- read.csv("x.csv") # comes back in as a data frame
hist(x$x)
dip.test(x$x)
Hartigans' dip test for unimodality / multimodality
data: x$x
D = 0.15217, p-value = 2.216e-05
alternative hypothesis: non-unimodal, i.e., at least bimodal
If you were to save the file to a .RDS instead of .csv then you could avoid this problem.
You could also check if your data frame contains any non-numeric characters as follows:
which(!grepl('^[0-9]',your_data_frame[[1]]))
Related
I was just going through a tremendous headache caused by read_csv messing up my data by substituting content with NA while reading simple and clean csv files.
I’m iterating over multiple large csv files that add up to millions of observations. Some columns contain quite some NA for some variables.
When reading a csv that contains NA in a certain column for the first 1000 + x observations, read_csv populates the entire column with NA and thus, the data is lost for further operations.
The warning message “Warning: x parsing failure” is shown, but as I’m reading multiple files I cannot check this file by file. Still, I would not know an automated fix for the parsing problem indicated also with problems(x)
Using read.csv instead of read_csv does not cause the problem, but it is slow and I run into encoding issues (using different encodings requires too much memory for large files).
An option to overcome this bug is to add a first observation (first row) to your data that contains something for each column, but still I need to read the file first somehow.
See a simplified example below:
##create a dtafrane
df <- data.frame( id = numeric(), string = character(),
stringsAsFactors=FALSE)
##poluate columns
df[1:1500,1] <- seq(1:1500)
df[1500,2] <- "something"
# variable string contains the first value in obs. 1500
df[1500,]
## check the numbers of NA in variable string
sum(is.na(df$string)) # 1499
##write the df
write_csv(df, "df.csv")
##read the df with read_csv and read.csv
df_readr <- read_csv('df.csv')
df_read_standard <- read.csv('df.csv')
##check the number of NA in variable string
sum(is.na(df_readr$string)) #1500
sum(is.na(df_read_standard$string)) #1499
## the read_csv files is all NA for variable string
problems(df_readr) ##What should that tell me? How to fix it?
Thanks to MrFlick for giving the answering comment on my questions:
The whole reason read_csv can be faster than read.csv is because it can make assumptions about your data. It looks at the first 1000 rows to guess the column types (via guess_max) but if there is no data in a column it can't guess what's in that column. Since you seem to know what's supposed to be in the columns, you should use the col_types= parameter to tell read_csv what to expect rather than making it guess. See the ?readr::cols help page to see how to tell read_csv what it needs to know.
Also guess_max = Inf overcomes the problem, but the speed advantage of read_csv seems to be lost.
I am trying to do some analyses with R and experienced some problems when doing it with my Macbook. When reading the csv file in R it tells me that the numeric values are empty.
That's how it looks like when I try to run an analysis:
pall.values = numeric()
df <- data.frame(Estimate=numeric(50), P.value=numeric(50))
for (i in 2:51){ #change the column range based on your data sheet
x <- cor.test(fdata[,c(i)],fdata$ARHQ_dad)
df$Estimate[i-3]=x$estimate
df$P.value[i-3]=x$p.value
}
Then this error occurs:
Error in cor.test.default(fdata[, c(i)], fdata$ARHQ_dad) : 'x' must be
a numeric vector
The csv itself recognizes the values as numbers since I used the Data to Column function and divided the columns by spaces and commas. However, in R it doesn't seem to work...
I hope somebody knows the answer to this (simple) problem.
I am trying to read data out of a csv-file.
The data consists of small integer numbers (53, 98 ...)
The csv was made with OpenOffice, the data stood there in the first column
one number in each row.
reading data was simple (no problem at all):
BirthNumbers <- read.csv(“/Users/.../RawData.csv”, header=FALSE)
Now I try to calculate mean(BirthNumbers) (for example),
but it is not possible, the error message:
x is not numeric
Where is my mistake?
Thanks for all help
Norbert
It's probably being read in as characters.
Try mean(as.numeric(BirthNumbers))
As per https://stat.ethz.ch/R-manual/R-devel/library/utils/html/read.table.html (see Value section), read.csv returns a data frame.
You should be calling mean on the column of the data frame. Since you have no headers (given your header = FALSE), most likely the column is called V1 (verify by doing head(BirthNumbers) or colnames(BirthNumbers)), so you should do mean(BirthNumbers$V1).
I am aware that there are similar questions on this site, however, none of them seem to answer my question sufficiently.
This is what I have done so far:
I have a csv file which I open in excel. I manipulate the columns algebraically to obtain a new column "A". I import the file into R using read.csv() and the entries in column A are stored as factors - I want them to be stored as numeric. I find this question on the topic:
Imported a csv-dataset to R but the values becomes factors
Following the advice, I include stringsAsFactors = FALSE as an argument in read.csv(), however, as Hong Ooi suggested in the page linked above, this doesn't cause the entries in column A to be stored as numeric values.
A possible solution is to use the advice given in the following page:
How to convert a factor to an integer\numeric without a loss of information?
however, I would like a cleaner solution i.e. a way to import the file so that the entries of column entries are stored as numeric values.
Cheers for any help!
Whatever algebra you are doing in Excel to create the new column could probably be done more effectively in R.
Please try the following: Read the raw file (before any excel manipulation) into R using read.csv(... stringsAsFactors=FALSE). [If that does not work, please take a look at ?read.table (which read.csv wraps), however there may be some other underlying issue].
For example:
delim = "," # or is it "\t" ?
dec = "." # or is it "," ?
myDataFrame <- read.csv("path/to/file.csv", header=TRUE, sep=delim, dec=dec, stringsAsFactors=FALSE)
Then, let's say your numeric columns is column 4
myDataFrame[, 4] <- as.numeric(myDataFrame[, 4]) # you can also refer to the column by "itsName"
Lastly, if you need any help with accomplishing in R the same tasks that you've done in Excel, there are plenty of folks here who would be happy to help you out
In read.table (and its relatives) it is the na.strings argument which specifies which strings are to be interpreted as missing values NA. The default value is na.strings = "NA"
If missing values in an otherwise numeric variable column are coded as something else than "NA", e.g. "." or "N/A", these rows will be interpreted as character, and then the whole column is converted to character.
Thus, if your missing values are some else than "NA", you need to specify them in na.strings.
If you're dealing with large datasets (i.e. datasets with a high number of columns), the solution noted above can be manually cumbersome, and requires you to know which columns are numeric a priori.
Try this instead.
char_data <- read.csv(input_filename, stringsAsFactors = F)
num_data <- data.frame(data.matrix(char_data))
numeric_columns <- sapply(num_data,function(x){mean(as.numeric(is.na(x)))<0.5})
final_data <- data.frame(num_data[,numeric_columns], char_data[,!numeric_columns])
The code does the following:
Imports your data as character columns.
Creates an instance of your data as numeric columns.
Identifies which columns from your data are numeric (assuming columns with less than 50% NAs upon converting your data to numeric are indeed numeric).
Merging the numeric and character columns into a final dataset.
This essentially automates the import of your .csv file by preserving the data types of the original columns (as character and numeric).
Including this in the read.csv command worked for me: strip.white = TRUE
(I found this solution here.)
version for data.table based on code from dmanuge :
convNumValues<-function(ds){
ds<-data.table(ds)
dsnum<-data.table(data.matrix(ds))
num_cols <- sapply(dsnum,function(x){mean(as.numeric(is.na(x)))<0.5})
nds <- data.table( dsnum[, .SD, .SDcols=attributes(num_cols)$names[which(num_cols)]]
,ds[, .SD, .SDcols=attributes(num_cols)$names[which(!num_cols)]] )
return(nds)
}
I had a similar problem. Based on Joshua's premise that excel was the problem I looked at it and found that the numbers were formatted with commas between every third digit. Reformatting without commas fixed the problem.
So, I had the similar situation here in my data file when I readin as a csv. All the numeric value were turned into char. But in my file there was a value with a word "Filtered" instead of NA. I converted "Filtered" to NA in vim editor of linux terminal with a command <%s/Filtered/NA/g> and saved this file and later used it and read it in R, all the values were num type and not char type any more.
Looks like character value "Filtered" was inducing all values to be char format.
Charu
Hello #Shawn Hemelstrand here are the steps in detail below:
example matrix file.csv having 'Filtered' word in it
I opened the file.csv in linux command terminal
vi file.csv
then press "Esc shift:"
and type the following command at the bottom
"%s/Filtered/NA/g"
press enter
then press "Esc shift:"
write "wq" at the bottom (this save the file and quit vim editor)
then in R script I read the file
data<- read.csv("file.csv", sep = ',', header = TRUE)
str(data)
All columns were num type which were earlier char type.
In case you need more help, it would be easier to share your txt or csv file.
I am very new to R and I am having trouble accessing a dataset I've imported. I'm using RStudio and used the Import Dataset function when importing my csv-file and pasted the line from the console-window to the source-window. The code looks as follows:
setwd("c:/kalle/R")
stuckey <- read.csv("C:/kalle/R/stuckey.csv")
point <- stuckey$PTS
time <- stuckey$MP
However, the data isn't integer or numeric as I am used to but factors so when I try to plot the variables I only get histograms, not the usual plot. When checking the data it seems to be in order, just that I'm unable to use it since it's in factor form.
Both the data import function (here: read.csv()) as well as a global option offer you to say stringsAsFactors=FALSE which should fix this.
By default, read.csv checks the first few rows of your data to see whether to treat each variable as numeric. If it finds non-numeric values, it assumes the variable is character data, and character variables are converted to factors.
It looks like the PTS and MP variables in your dataset contain non-numerics, which is why you're getting unexpected results. You can force these variables to numeric with
point <- as.numeric(as.character(point))
time <- as.numeric(as.character(time))
But any values that can't be converted will become missing. (The R FAQ gives a slightly different method for factor -> numeric conversion but I can never remember what it is.)
You can set this globally for all read.csv/read.* commands with
options(stringsAsFactors=F)
Then read the file as follows:
my.tab <- read.table( "filename.csv", as.is=T )
When importing csv data files the import command should reflect both the data seperation between each column (;) and the float-number seperator for your numeric values (for numerical variable = 2,5 this would be ",").
The command for importing a csv, therefore, has to be a bit more comprehensive with more commands:
stuckey <- read.csv2("C:/kalle/R/stuckey.csv", header=TRUE, sep=";", dec=",")
This should import all variables as either integers or numeric.
None of these answers mention the colClasses argument which is another way to specify the variable classes in read.csv.
stuckey <- read.csv("C:/kalle/R/stuckey.csv", colClasses = "numeric") # all variables to numeric
or you can specify which columns to convert:
stuckey <- read.csv("C:/kalle/R/stuckey.csv", colClasses = c("PTS" = "numeric", "MP" = "numeric") # specific columns to numeric
Note that if a variable can't be converted to numeric then it will be converted to factor as default which makes it more difficult to convert to number. Therefore, it can be advisable just to read all variables in as 'character' colClasses = "character" and then convert the specific columns to numeric once the csv is read in:
stuckey <- read.csv("C:/kalle/R/stuckey.csv", colClasses = "character")
point <- as.numeric(stuckey$PTS)
time <- as.numeric(stuckey$MP)
I'm new to R as well and faced the exact same problem. But then I looked at my data and noticed that it is being caused due to the fact that my csv file was using a comma separator (,) in all numeric columns (Ex: 1,233,444.56 instead of 1233444.56).
I removed the comma separator in my csv file and then reloaded into R. My data frame now recognises all columns as numbers.
I'm sure there's a way to handle this within the read.csv function itself.
This only worked right for me when including strip.white = TRUE in the read.csv command.
(I found the solution here.)
for me the solution was to include skip = 0
(number of rows to skip at the top of the file. Can be set >0)
mydata <- read.csv(file = "file.csv", header = TRUE, sep = ",", skip = 22)