CODEWITHSUNDEEP
rcsv
curbholes
curbholes

Reputation: 557

replace comma with dot in scientific notation in r

I want to read a csv-file that uses scientific notation and comma as a decimal separator into a data frame or vector. Then I want to use this data for further calculations. The problem is that R does not recognize the data as numeric. How can I translate this scientific notation with commas into the "correct" scientific notation with dots so I can use as numeric values?

I tried the following:

mferg_1<-read.csv("file.csv",sep=";",dec=",",header=FALSE)

When I look at the dataframe mferg_1 the following appears (excerpt):

          V2        V3        V4        V5
14 3,063E+01 1,775E-02 6,641E-07 3,747E-02

I thought that I could replace the commas by using gsub or sub:

mferg_1<-sub(",",".",mferg_1)

But then mferg_1 looks like this:

[1] "425" "388" "535" "472"

I fear there is an easy way to solve this problem but I have not been able to find it.

Upvotes: 3

Views: 16237

Answers (1)

Carlos Cinelli
Carlos Cinelli

Reputation: 11597

You probably have something in your csv (a character line) that does not allow converting the columns to number, because the dec = "," parameter should work. See this example with your data:

text <- "3,063E+01 1,775E-02 6,641E-07 3,747E-02"
read.table(text=text, dec = ",")
     V1      V2        V3      V4
1 30.63 0.01775 6.641e-07 0.03747

Now, if you can't identify the problem (find what is preventing R to identify your columns as numeric), you could use gsub. 

df <- read.table(text=text)
df <- sapply(df, gsub, pattern = ",", replacement= ".")
df <- sapply(df, as.numeric)
     V1        V2        V3        V4 
3.063e+01 1.775e-02 6.641e-07 3.747e-02

Upvotes: 7

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