[Numpy-discussion] Numpy 2D array from a list error

Dave Wood davejwood@gmail....
Wed Sep 23 10:00:46 CDT 2009

 "If the text file has 'numbers and strings' how is numpy meant to know
what dtype to use?
Please try genfromtxt especially if columns contain both numbers and

Well, I suppose they are all considered to be strings here. I haven't tried
to convert the numbers to floats yet.

"What happens if you read a file instead of using stdin?"

Same problem

"It is possible that one or more rows have multiple sequential delimiters.
Please check the row lengths of your 'data' variable after doing:"

Already done, they all have the same number of rows.
The fact that the script works with the first 40k lines, and also with the
last 40k lines suggests to me that there is no problem with the file.
(I calculate column means and standard deviations later in the script - it's
only the first two columns which can't be cast to floating point numbers)

"Really without the input or system, it is hard to say anything.
If you really know your data I would suggest preallocating the array and
updating the array one line at a time to avoid the large multiple
intermediate objects."

I'm running on linux. My machine is redhat with 2GB RAM, but when memory
became an issue I tried running on other Linux machines with much greater
RAM capacities. I don't know what distos.

I just tried preallocating the array and updating it one line at a time, and
that works fine. Thanks very much for the suggestion. :)
This doesn't seem like the expected behaviour though and the error message
seems wrong.

Many thanks,


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