Writing dynamically-sized arrays to file in python3 - python-3.x

Question

I am trying to write ASCII data to a text file in the following format:
Time Heat Flux ...
0.023 1.793 ...
.
.
.
The text header comes from a list of tags with dimension 1 x n and the numeric data with dimension m x n. I usually print this information when I know the number of rows and columns a priori in this manner:
# ... open file object, etc.
# Print header
print('%16s \t %16s' % ('Time', 'Heat Flux'), file=fileObject)
for ii in range(0, len(heatFlux):
print('%16.3f \t %16.3f' % (heatFlux[ii][0], heatFlux[ii][1]), file=fileObject)
I want to have generic code that allows me to write these files with a dynamically-sized array (in terms of number of columns). I've tried to generate a string and insert the tags and spaces, which I then write to file, but I am not sure how to "format-print" the string itself.
For example, I was trying
tagHeader = []
for tag in keyTags:
tagHeader = tagHeader + tag + '\t'
# ...
print(tagHeader, file=fileObject)
Can someone help me with this? Thanks!

Answer 1

If you have a list with the header and a 2D data structure you can do something like this:
def table(header, data):
print('\t'.join(['%16s'] * len(header)) % tuple(header))
for row in data:
print('\t'.join(['%16.3f'] * len(header)) % tuple(row))
Here are some tests:
header1 = ['Time', 'Heat Flux']
header2 = ['Time', 'Heat Flux', 'New col']
header3 = ['This', 'is', 'a', 'test']
data1 = [[uniform(-10, 10) for _ in range(len(header1))] for _ in range(randint(2, 10))]
data2 = [[uniform(-10, 10) for _ in range(len(header2))] for _ in range(randint(2, 10))]
data3 = [[uniform(-10, 10) for _ in range(len(header3))] for _ in range(randint(2, 10))]
table(header1, data1)
table(header2, data2)
table(header3, data3)
Output:
Time Heat Flux
7.037 -1.528
8.058 5.649
Time Heat Flux New col
-9.590 4.846 -4.024
-8.597 9.718 -8.174
9.260 -0.947 -6.675
3.401 -5.101 8.323
0.099 -6.582 3.951
This is a test
-2.126 -0.678 4.782 -7.849
-9.007 -0.019 -4.402 8.017
-7.399 -7.617 6.235 9.320
-0.486 -5.304 -4.723 1.946
2.743 -2.150 -6.779 -2.099
-7.499 -2.618 -9.918 0.674
8.912 -6.648 -7.865 -0.101
0.682 -0.414 7.677 7.167
-3.105 -6.562 6.970 -2.147