need to put a nested Dict into a text file

Question

I have a nested dict like this

d={ time1 : column1 : {data1,data2,data3}
            column2 : {data1,data2,data3}        
            column3 : {data1,data2,data3}     #So on.
    time2 : {column1: }       #Same as Above
  }

data1,data2,data3 represent the type of data and not the data itself I need to put this dict into a file like this.

Timestamp col1/data1 Col1/data2 col1/data3 col2/data1 col2/data2 col2/data3 (So on...)

My problem is How do I ensure that the text goes under the corresponding column?
i.e Say I have put some text under time1 column14 and I again come across column14 in another timestamp. How do I keep track of the location of these columns in the text file?

The columns are just numbers (in string form)

Answer 1

I would do it like this:

#get the row with maximum number of columns
maxrowlen = 0
maxrowkey = ""
for timesid in d.keys():
    if len(timesid.keys()) > maxrowlen:
         maxrowlen = len(timesid.keys())
         maxrowkey = timesid
maxrowcols = sorted(d[maxrowkey].keys())

# prepare the writing
cell_format = "%10r"    # or whatever suits your data

# create the output string
lines = []
for timesid in d.keys(): # go through all times
    line = ""
    for col in maxrowcols:  # go through the standard columns
         colstr = ""
         if col in d[timesid].keys():   # create an entry for each standard column
             colstr += cell_format % d[timesid][col]  # either from actual data
         else:
             colstr += cell_format % ""                      # or blanks
         line += colstr
    lines.append(line)

text = "\n".join(lines)

Answer 2

I would use JSON.

In Python 2.6 it's directly available, in earlier Python's you have to download and install it.

try:
    import json
exception ImportError:
    import simplejson as json

out= open( "myFile.json", "w" )
json.dump( { 'timestamp': time.time(), 'data': d }, indent=2 )
out.close()

Works nicely. Easy to edit manually. Easy to parse.