How can you read a CSV file in R with different number of columns

Deep in the ?read.table documentation there is the following:

The number of data columns is determined by looking at the first five lines of input (or the whole file if it has less than five lines), or from the length of col.names if it is specified and is longer. This could conceivably be wrong if fill or blank.lines.skip are true, so specify col.names if necessary (as in the ‘Examples’).

Therefore, let's define col.names to be length X (where X is the max number of fields in your dataset), and set fill = TRUE:

dat <- textConnection("12223, University12227, bridge, Sky12828, Sunset13801, Ground14853, Tranceamerica14854, San Francisco15595, shibuya, Shrine16126, fog, San Francisco16520, California, ocean, summer, golden gate, beach, San Francisco")read.table(dat, header = FALSE, sep = ",",   col.names = paste0("V",seq_len(7)), fill = TRUE)     V1             V2             V3      V4           V5     V6             V71 12223     University                                                          2 12227         bridge            Sky                                           3 12828         Sunset                                                          4 13801         Ground                                                          5 14853  Tranceamerica                                                          6 14854  San Francisco                                                          7 15595        shibuya         Shrine                                           8 16126            fog  San Francisco                                           9 16520     California          ocean  summer  golden gate  beach  San Francisco

If the maximum number of fields is unknown, you can use the nifty utility function count.fields (which I found in the read.table example code):

count.fields(dat, sep = ',')# [1] 2 3 2 2 2 2 3 3 7max(count.fields(dat, sep = ','))# [1] 7

Possibly helpful related reading: Only read limited number of columns in R

You could read the data like this:

dat <- textConnection("12223, University12227, bridge, Sky12828, Sunset13801, Ground14853, Tranceamerica14854, San Francisco15595, shibuya, Shrine16126, fog, San Francisco16520, California, ocean, summer, golden gate, beach, San Francisco")dat <- readLines(dat)dat <- strsplit(dat, ",")

This results in a list.

This does seem to work (following @BlueMagister's suggestion):

tt <- read.table("~/Downloads/tmp.csv", fill=TRUE, header=FALSE,           sep=",", colClasses=c("numeric", rep("character", 6)))names(tt) <- paste("V", 1:7, sep="")     V1             V2             V3      V4           V5     V6             V71 12223     University                                                          2 12227         bridge            Sky                                           3 12828         Sunset                                                          4 13801         Ground                                                          5 14853  Tranceamerica                                                          6 14854  San Francisco                                                          7 15595        shibuya         Shrine                                           8 16126            fog  San Francisco                                           9 16520     California          ocean  summer  golden gate  beach  San Francisco