def read_solarsimulator_plot_file(filename, position):
"""Read a datafile from a solarsimulator measurement and return the content of
the voltage column and the selected current column.
:param filename: full path to the solarsimulator measurement data file
:param position: the position of the cell the currents of which should be read.
:type filename: str
:type position: str
:return:
all voltages in Volt, then all currents in Ampere
:rtype: list of float, list of float
:raises PlotError: if something wents wrong with interpreting the file (I/O,
unparseble data)
"""
try:
datafile_content = StringIO(open(filename).read())
except IOError:
raise PlotError("Data file could not be read.")
for line in datafile_content:
if line.startswith("# Positions:"):
positions = line.partition(":")[2].split()
break
else:
positions = []
try:
column = positions.index(position) + 1
except ValueError:
raise PlotError("Cell position not found in the datafile.")
datafile_content.seek(0)
try:
return numpy.loadtxt(datafile_content, usecols=(0, column), unpack=True)
except ValueError:
raise PlotError("Data file format was invalid.")
def _cache_store_chunks(items, key, expiration):
"""Store a list of items as chunks in the cache.
The list of items will be combined into chunks and stored in the
cache as efficiently as possible. Each item in the list will be
yielded to the caller as it's fetched from the list or generator.
"""
chunks_data = StringIO()
chunks_data_len = 0
read_start = 0
item_count = 0
i = 0
for data, has_item, item in items:
if has_item:
yield item
item_count += 1
chunks_data.write(data)
chunks_data_len += len(data)
if chunks_data_len > CACHE_CHUNK_SIZE:
# We have enough data to fill a chunk now. Start processing
# what we've stored and create cache keys for each chunk.
# Anything remaining will be stored for the next round.
chunks_data.seek(read_start)
cached_data = {}
while chunks_data_len > CACHE_CHUNK_SIZE:
chunk = chunks_data.read(CACHE_CHUNK_SIZE)
chunk_len = len(chunk)
chunks_data_len -= chunk_len
read_start += chunk_len
# Note that we wrap the chunk in a list so that the cache
# backend won't try to perform any conversion on the string.
cached_data[make_cache_key('%s-%d' % (key, i))] = [chunk]
i += 1
# Store the keys in the cache in a single request.
cache.set_many(cached_data, expiration)
# Reposition back at the end of the stream.
chunks_data.seek(0, 2)
if chunks_data_len > 0:
# There's one last bit of data to store. Note that this should be
# less than the size of a chunk,
assert chunks_data_len <= CACHE_CHUNK_SIZE
chunks_data.seek(read_start)
chunk = chunks_data.read()
cache.set(make_cache_key('%s-%d' % (key, i)), [chunk], expiration)
i += 1
cache.set(make_cache_key(key), '%d' % i, expiration)
def _cache_store_chunks(items, key, expiration):
"""Store a list of items as chunks in the cache.
The list of items will be combined into chunks and stored in the
cache as efficiently as possible. Each item in the list will be
yielded to the caller as it's fetched from the list or generator.
"""
chunks_data = StringIO()
chunks_data_len = 0
read_start = 0
item_count = 0
i = 0
for data, has_item, item in items:
if has_item:
yield item
item_count += 1
chunks_data.write(data)
chunks_data_len += len(data)
if chunks_data_len > CACHE_CHUNK_SIZE:
# We have enough data to fill a chunk now. Start processing
# what we've stored and create cache keys for each chunk.
# Anything remaining will be stored for the next round.
chunks_data.seek(read_start)
cached_data = {}
while chunks_data_len > CACHE_CHUNK_SIZE:
chunk = chunks_data.read(CACHE_CHUNK_SIZE)
chunk_len = len(chunk)
chunks_data_len -= chunk_len
read_start += chunk_len
# Note that we wrap the chunk in a list so that the cache
# backend won't try to perform any conversion on the string.
cached_data[make_cache_key('%s-%d' % (key, i))] = [chunk]
i += 1
# Store the keys in the cache in a single request.
cache.set_many(cached_data, expiration)
# Reposition back at the end of the stream.
chunks_data.seek(0, 2)
if chunks_data_len > 0:
# There's one last bit of data to store. Note that this should be
# less than the size of a chunk,
assert chunks_data_len <= CACHE_CHUNK_SIZE
chunks_data.seek(read_start)
chunk = chunks_data.read()
cache.set(make_cache_key('%s-%d' % (key, i)), [chunk], expiration)
i += 1
cache.set(make_cache_key(key), '%d' % i, expiration)
