问题
I came across a strange problem when trying to export an R dataframe to a csv file. The dataframe contains some big numbers, but when they are written to the csv file, they "lose" the decimal part and are instead written without it. But not like one would expect, but like this:
Say 3224571816.5649 is the correct value in R. When written to csv, it becomes 32245718165649.
I am using the write.csv2 function to write the csv. The separators are correct, as it works normally for smaller values. Is the problem occurring because the number (with decimals) is bigger than 32bit?
And more importantly, how can I solve this, as I have a whole dataframe with values as big (or bigger) than this? Also, it has to be written in to a csv.
回答1:
write.csv2 is intended for a different standard of csv (Western European styling, which based on your use of a "." as a decimal indicator, I am guessing you are not looking for). write.csv2 uses a comma as a decimal indicator and a semicolon as the field delimiter, so if you are trying to read the result in as a comma separated file, it will look strange indeed.
I suggest you use write.csv (or even better, write.table) to output your file. write.csv assumes a comma separator and period for decimal marker.
both write.csv and write.csv2 are just wrappers for write.table, which is the underlying method. In general, I recommend use of write.table because it does not assume your region and you can explicitly pass it sep = ",", dec = ".", etc. This not only lets you know what you are using for sure, but it also makes your code a lot more readable.
for more, check the rdocumentation.org site for write.table: https://www.rdocumentation.org/packages/utils/versions/3.5.3/topics/write.table
来源：https://stackoverflow.com/questions/55299050/exporting-large-number-to-csv-from-r