Description Usage Arguments Details Value Examples
sfc
is the function for computing the substance flow with
the input file "data" and "model", and furtherly analyzing the
uncertainty of the computing results which are propagated from
the activity data and parameters.
1 2 
data 
a path for a ".csv" file or a data frame which contains
the basic data for substance flow computation. The details of

model 
a path for a text file or a string vector which contains
the formulas for substance flow computation. The details of 
sample.size 
a single value, interpreted as an integer. The
details of 
rand.seed 
a single value, interpreted as an integer or NULL,
which is the same with 
check 
logical. If FALSE, the summary of uncertainty analysis
will use all the samples. IF TRUE, they only use the valid samples.
The details of 
inner 
logical. IF TRUE, the intermediate results will be returnd, such as the input samples and the results for each sample. 
... 
Further arguments to be passed to both 
There are two important inputs in sfc
function: data
and model
. "data" is a table in the form of ".csv" which includes
a line of the header and the other lines of the specific data. The header
can be divided into two categories: special fields and general fields.
Special fields represent the fields which are meaningful for computation,
while general fields only describe each row in details which will not be
used in computation, such as the description of the concept or unit of a
variable. So general fields are not as necessary as special fields. Special
fields can also be divided into two parts: fixed fields and flexible fields.
Fixed fields contains: NAME, DATA, TIME, SITE and DIST. Flexible fields
contains: P1, P2, P3, ... and C1, C2, C3, ... NAME means the variable name.
DATA means the variable value. TIME means the specific time while SITE means
the specific place where the variable observed. DIST is a character of
distribution in Distributions
, such as "norm", "unif", etc.
P1, P2, P3, ... are the distribution parameters which are flexible because
different distribution has different number or meaning of parameters.
C1, C2, C3, ... are supplementary fields for other distinguished information
like TIME and SITE. All the letters of field names are in the capital form
to distinguish with the normal R variables or functions.
"model" is a special R code fragment which only contains flow computation
expressions, like "PF[i, j, ] = DX * PX" or "PF[i, j, ] < DX * PX". Here,
"i" is the start node and "j" is the end node. "DX" and "PX" represent
activity data and parameters, respectively. They also correspond to the
"NAME" field in the "data" file. "PF[i, j, ]" is an array which means the
flow from "i" to "j", while "PF" is the default flow name. If you do not
like coding, this package provides another alternative: to write model as
into a ".csv" file. This file contains four critical fields: NAME, START,
END and FUN. They are required fields while you can add other optional fields
to make the model more readable freely. The NAME field is used to define
flow label, e.g. "PF_01" labels "PF[i, j, ]". The START and END field are
used to define the start node "i" and the end node "j" in "PF[i, j, ]".
The last one, "FUN" is used to define the formula to calculate the flow,
such as the righthand expression "DX * PX". To keep the code easy and simple,
some auxiliary functions are supplied: p
, comp0
, suma
and rnone
. p
is used to keep flow positive while the negative
value will be set zero. comp0
is used to change the value near zero
to be zero. suma
is used to sum an array at the margin m
.
rnone
is used to sample the same value.
If sample.size
are greater than 1, the uncertainty of substance flow
computation result, i.e. "PF[i, j, ]", will be evaluated. However, we
will still compute the scenario when sample.size
= 1, which
represent the expected scenario (or most valid scenario), to compare with
each result of each sample. If the sign of each flow are the same, the
sample are valid, otherwise are invalid. So the sample.size
in
the result list is the valid sample size. To trigger the above comparation,
check
should be set TRUE.
sfc
returns a list which contains four objects: result
,
sample.size
, sample
and inner.result
. result
is a data frame of substance flow computation result. sample.size
is the sample size of valid samples. sample
is the data frame of
the input samples. inner.result
is the data frame of substance flow
computation result for each sample.
1 2 3 4 5 6 7 8 9 10 11  library(sfc)
## model as txt
data < system.file("extdata", "data_utf8.csv", package = "sfc")
model < system.file("extdata", "model_utf8.txt", package = "sfc")
sfc(data, model, sample.size = 100, fileEncoding = "UTF8")
## model as csv
data < system.file("extdata", "data_utf8.csv", package = "sfc")
model < system.file("extdata", "model_utf8.csv", package = "sfc")
sfc(data, model, fileEncoding = "UTF8")

Add the following code to your website.
For more information on customizing the embed code, read Embedding Snippets.