Well actually no. My data files have more than one line. Guess I'm getting many things wrong. The data look like: oldfile:

mask    x    y    dln9476326lce    dln94930101lc
0    8852.68825    442495.5253    82293.02    0
0    9913.98125    442495.5253    82751.22    0
0    10975.27425    442495.5253    83238.23    0
0    10975.27425    441434.2323    81704.7    0
0    12036.56725    440372.9393    80174.36    0
0    12036.56725    439311.6463    80174.36    0
0    12036.56725    438250.3533    78647.4    0
0    13097.86025    438250.3533    79192.59    0
0    13097.86025    437189.0603    77679.91    0
0    13097.86025    436127.7673    77679.91    0
<snip>

I haven't included all the columns, but there are 5 more.
[download]

newfile:

mask    x    y    dln9476331lc
0    23710.79025    396859.92632    0
0    27955.96225    396859.92632    0.2530461
0    29017.25525    395798.63332    0.4151559
0    29017.25525    394737.34032    2.826168
0    19465.61825    393676.04732    0
<snip>
[download]

The files always have the same name in each directory, the same number of lines, and the same structure (within each directory, but different across directories). They are output from a GIS sampling program. The only difference is the days on which they were sampled. Files look like:

C:\neaq\ArcData\bluefin\data_dens\1994_sptr>dir

10.06.94.txt
10.07.94.txt
7.10.94.txt
7.11.94.txt
7.12.94.txt
7.14.94.txt
<snip>

C:\neaq\ArcData\bluefin\data_analysis\1994sptr\data>dir
10.06.94.txt
10.07.94.txt
7.10.94.txt
7.11.94.txt
7.12.94.txt
7.14.94.txt
<snip>
[download]