This function allows to perform very fast filter operations on large ITCH files. The messages are written to another ITCH file.
Usage
filter_itch(
infile,
outfile,
filter_msg_class = NA_character_,
filter_msg_type = NA_character_,
filter_stock_locate = NA_integer_,
min_timestamp = bit64::as.integer64(NA),
max_timestamp = bit64::as.integer64(NA),
filter_stock = NA_character_,
stock_directory = NA,
skip = 0,
n_max = -1,
append = FALSE,
overwrite = FALSE,
gz = FALSE,
buffer_size = -1,
quiet = FALSE,
force_gunzip = FALSE,
force_cleanup = TRUE
)Arguments
- infile
the input file where the messages are taken from, can be a gz-archive or a plain ITCH file.
- outfile
the output file where the filtered messages are written to. Note that the date and exchange information from the
infileare used, see alsoadd_meta_to_filename()for further information.- filter_msg_class
a vector of classes to load, can be "orders", "trades", "modifications", ... see also
get_msg_classes(). Default value is to take all message classes.- filter_msg_type
a character vector, specifying a filter for message types. Note that this can be used to only return 'A' orders for instance.
- filter_stock_locate
an integer vector, specifying a filter for locate codes. The locate codes can be looked up by calling
read_stock_directory()or by downloading from NASDAQ by usingdownload_stock_directory(). Note that some message types (e.g., system events, MWCB, and IPO) do not use a locate code.- min_timestamp
an 64 bit integer vector (see also
bit64::as.integer64()) of minimum timestamp (inclusive). Note: min and max timestamp must be supplied with the same length or left empty.- max_timestamp
an 64 bit integer vector (see also
bit64::as.integer64()) of maxium timestamp (inclusive). Note: min and max timestamp must be supplied with the same length or left empty.- filter_stock
a character vector, specifying a filter for stocks. Note that this a shorthand for the
filter_stock_locateargument, as it tries to find the stock_locate based on thestock_directoryargument, if this is not found, it will try to extract the stock directory from the file, else an error is thrown.- stock_directory
A data.frame containing the stock-locate code relationship. As outputted by
read_stock_directory(). Only used iffilter_stockis set. To download the stock directory from NASDAQs server, usedownload_stock_directory().- skip
Number of messages to skip before starting parsing messages, note the skip parameter applies to the specific message class, i.e., it would skip the messages for each type (e.g., skip the first 10 messages for each class).
- n_max
Maximum number of messages to parse, default is to read all values. Can also be a data.frame of msg_types and counts, as returned by
count_messages(). Note the n_max parameter applies to the specific message class not the whole file.- append
if the messages should be appended to the outfile, default is false. Note, this is helpful if
skipand orn_maxare used for batch filtering.- overwrite
if an existing outfile with the same name should be overwritten. Default value is false
- gz
if the output file should be gzip-compressed. Note that the name of the output file will be appended with .gz if not already present. The final output name is returned. Default value is false.
- buffer_size
the size of the buffer in bytes, defaults to 1e8 (100 MB), if you have a large amount of RAM, 1e9 (1GB) might be faster
- quiet
if TRUE, the status messages are suppressed, defaults to FALSE
- force_gunzip
only applies if the input file is a gz-archive and a file with the same (gunzipped) name already exists. if set to TRUE, the existing file is overwritten. Default value is FALSE
- force_cleanup
only applies if the input file is a gz-archive. If force_cleanup=TRUE, the gunzipped raw file will be deleted afterwards. Only applies when the gunzipped raw file did not exist before.
Value
the name of the output file (maybe different from the inputted outfile due to adding the date and exchange), silently
Details
Note that this can be especially useful on larger files or where memory is not large enough to filter the datalimits the analysis.
As with the read_itch() functions, it allows to filter for
msg_class, msg_type, stock_locate/stock, and
timestamp.
Examples
infile <- system.file("extdata", "ex20101224.TEST_ITCH_50", package = "RITCH")
outfile <- tempfile(fileext = "_20101224.TEST_ITCH_50")
filter_itch(
infile, outfile,
filter_msg_class = c("orders", "trades"),
filter_msg_type = "R", # stock_directory
skip = 0, n_max = 100
)
#> [Filter] skip: 0 n_max: 100 (1 - 100)
#> [Filter] msg_type: 'R', 'A', 'F', 'P', 'Q', 'B'
#> [Bytes] scanned 465048, filtered 8527
#> [Messages] scanned 12012, filtered 203
#> [Done] in 0.11 secs at 4.17MB/s
# expecting 100 orders, 100 trades, and 3 stock_directory entries
count_messages(outfile)
#> [Counting] 203 total messages found
#> [Converting] to data.table
#> [Done] in 0.00 secs at 41.78MB/s
#> msg_type count
#> 1: S 0
#> 2: R 3
#> 3: H 0
#> 4: Y 0
#> 5: L 0
#> 6: V 0
#> 7: W 0
#> 8: K 0
#> 9: J 0
#> 10: h 0
#> 11: A 99
#> 12: F 1
#> 13: E 0
#> 14: C 0
#> 15: X 0
#> 16: D 0
#> 17: U 0
#> 18: P 100
#> 19: Q 0
#> 20: B 0
#> 21: I 0
#> 22: N 0
#> msg_type count
# check that the output file contains the same
res <- read_itch(outfile, c("orders", "trades", "stock_directory"))
#> [Counting] num messages 203
#> [Counting] num 'stock_directory' messages 3
#> [Counting] num 'orders' messages 100
#> [Counting] num 'trades' messages 100
#> [Converting] to data.table
#> [Done] in 0.11 secs at 76.96KB/s
sapply(res, nrow)
#> orders trades stock_directory
#> 100 100 3
res2 <- read_itch(infile, c("orders", "trades", "stock_directory"),
n_max = 100)
#> [Note] n_max overrides counting the messages. Number of messages may be off
#> [Filter] skip: 0 n_max: 100 (1 - 100)
#> [Counting] num 'stock_directory' messages 100
#> [Counting] num 'orders' messages 200
#> [Counting] num 'trades' messages 300
#> [Converting] to data.table
#> [Done] in 0.11 secs at 4.14MB/s
all.equal(res, res2)
#> [1] TRUE