CODEWITHSUNDEEP
rdata.table
Rodolphe LAMPE
Rodolphe LAMPE

Reputation: 1518

Read only one line with fread from data.table

I have the following file :

bla;bla;
0;1;2;3;4;

I want to read only the first line with fread (from data.table 1.10.0) :

fread('data/test.txt', nrows = 1, skip = 0, colClasses = "character", autostart = 0, header = F)

It produces the following warning :

Warning message: 
In fread("data/test.txt", nrows = 1, skip = 0, colClasses = "character",  : 
Starting data input on line 2 and discarding line 1 because it has too few or too many items to be column names or data: bla;bla;

Upvotes: 1

Views: 3699

Answers (1)

Etienne Moerman
Etienne Moerman

Reputation: 331

I don't think the present fread will work. The package description explicitly states

‘fread‘ is for regular delimited files; i.e., where every row has the same >number of columns. In future, secondary separator (sep2) may be specified within each column. Such columns will be read as type list where each cell >is itself a vector.

I tried the combination sep=";" and sep2=";", but that doesn't work.

With all this auto-detection going on I think some methods without auto-detection might be faster when you just want to read the first line.

Upvotes: 2

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