rsaga.grid.calculus(RSAGA)
rsaga.grid.calculus()所属R语言包：RSAGA
SAGA Module Grid Calculus
SAGA模块网格微积分
译者：生物统计家园网 机器人LoveR
描述----------Description----------
Perform Arithmetic Operations on Grids
执行算术运算网格
用法----------Usage----------
rsaga.grid.calculus(in.grids, out.grid, formula,
env = rsaga.env(), ...)
rsaga.linear.combination(in.grids, out.grid,
coef, cf.digits = 16, remove.zeros = FALSE,
remove.ones = TRUE, env = rsaga.env(), ...)
参数----------Arguments----------
参数：in.grids
input character vector: SAGA grid files (default file extension: .sgrd)
：输入字符向量：SAGA网格文件（默认文件扩展名：.sgrd）
参数：out.grid
output: grid file resulting from the cell-by-cell application of 'formula' to the grids. Existing files will be overwritten!
输出：网格文件导致从单元通过单元“公式”的网格中的应用。现有的文件将被覆盖！
参数：formula
character string of formula specifying the arithmetic operation to be performed on the in.grids (see Details); if this is a formula, only the right hand side will be used.
式的字符串上执行指定的算术运算的in.grids（详细），如果这是一个公式，只将被用于右手侧。
参数：coef
numeric: coefficient vector to be used for the linear combination of the in.grids. If coef as one more element than in.grids, the first one will be interpreted as an intercept.
数值：要用于的in.grids的线性组合的系数向量。如果coef作为一个元素比in.grids，第一个将被解释为一个拦截。
参数：cf.digits
integer: number of digits used when converting the coefficients to character strings (trailing zeros will be removed)
整数时使用的数字位数转换coefficients字符串（尾随零将被删除）
参数：remove.zeros
logical: if TRUE, terms (grids) with coefficient (numerically) equal to zero (after rounding to cf.digits digits) will be removed from the formula
逻辑：如果TRUE“条款（网格）的系数（数值）等于零（cf.digits数字四舍五入后）将被删除从公式
参数：remove.ones
logical: if TRUE (default), factors equal to 1 (after rounding to cf.digits digits) will be removed from the formula
逻辑：如果TRUE（默认），等于1（cf.digits数字四舍五入后）的因素将被从公式中删除
参数：env
character string, either '2.0.4' (default) or '2.0.5'; the command line arguments for the grid calculator module changed from SAGA GIS 2.0.4 to 2.0.5, the function is now able to handle both situations; if using a different SAGA GIS version, try one of these two options, or look at rsaga.get.usage and use rsaga.geoprocessor directly; sorry for the inconvenience
字符串，2 .0.4（默认）或2 .0.5; SAGA GIS的网格计算器模块的命令行参数改变2.0.4到2.0.5，现在的功能是能够处理这两种情况下;如果使用不同的SAGA GIS版本，请尝试这两个选项之一，或看rsaga.get.usage使用rsaga.geoprocessor直接的不便表示抱歉
参数：...
optional arguments to be passed to rsaga.geoprocessor, including the env RSAGA geoprocessing environment
可选参数传递给rsaga.geoprocessor，包括env RSAGAGEO处理环境
Details
详细信息----------Details----------
The in.grids are represented in the formula by the letters a (for in.grids[1]), b etc. Thus, if in.grids[1] is Landsat TM channel 3 and in.grids[2] is channel 4, the NDVI formula (TM3-TM4)/(TM3+TM4) can be represented by the character string "(a-b)/(a+b)" (any spaces are removed) or the formula ~(a-b)/(a+b) in the formula argument.
in.grids是代表中的formula的字母a（用于in.grids[1]）b等等。因此，如果in.grids[1]是Landsat TM遥感通道3和in.grids[2]是频道4，则的NDVI式（TM3-TM4）/（TM3 + TM4）可以表示为字符串"(a-b)/(a+b)"（任何空格被删除）或公式<X >~(a-b)/(a+b)参数。
In addition to +, -, *, and /, the following operators and functions are available for the formula definition:
除了+， - ，*，/，下列运算符和函数可用于formula定义：
^power
^电源
sin(a)sine
SIN（A）正弦
cos(a)cosine
余弦（一）余弦
tan(a)tangent
棕褐色（一）切线
asin(a)arc sine
ASIN（一）圆弧正弦
acos(a)arc cosine
ACOS（一）反余弦
atan(a)arc tangent
ATAN（）反正切
atan2(a,b)arc tangent of b/a
atan2的（一，二）b / a的弧正切
abs(a)absolute value
ABS（A）绝对值
int(a)convert to integer
（一）转换为整数
sqrt(a)square root
SQRT（）平方根
ln(a)natural logarithm
LN（一）自然对数
mod(a,b)modulo
MOD（A，B）模
gt(a, b)returns 1 if a greater b
GT（A，B）返回1，如果一个更大的b
lt(a, b)returns 1 if a lower b
LT（A，B）返回1，如果一个较低的b
eq(a, b)returns 1 if a equal b
式（A，B）返回1，如果等于B
ifelse(switch, x, y)returns x if switch equals 1 else y
ifelse（开关，X，Y），如果开关返回x等于1，否则Ÿ
Using remove.zeros=FALSE might have the side effect that no data areas in the grid with coefficient 0 are passed on to the results
使用remove.zeros=FALSE可能有副作用，无数据区传递网格中的系数为0的结果
值----------Value----------
The type of object returned depends on the intern argument passed to the rsaga.geoprocessor. For intern=FALSE it is a numerical error code (0: success), or otherwise (default)
返回的对象的类型取决于intern参数传递的rsaga.geoprocessor。对于intern=FALSE它是一个数字错误代码（0：成功），或以其他方式（默认）
注意----------Note----------
This function uses module 1 in the SAGA library grid_calculus.
此功能使用模块1在SAGA库grid_calculus中。
（作者）----------Author(s)----------
Alexander Brenning (R interface), Olaf Conrad (SAGA module)
参见----------See Also----------
local.function, focal.function, and multi.focal.function for a more flexible framework for combining grids or applying local and focal functions;
local.function，focal.function和multi.focal.function相结合的网格或应用本地和联络功能更灵活的框架;
实例----------Examples----------
## Not run: [＃不运行：]
# using SAGA grids:[使用SAGA格：]
# calculate the NDVI from Landsat TM bands 3 and 4:[计算NDVI从陆地卫星TM波段3和4：]
rsaga.grid.calculus(c("tm3.sgrd","tm4.sgrd"), "ndvi.sgrd", ~(a-b)/(a+b))
# apply a linear regression equation to grids:[应用线性回归方程网格：]
coefs = c(20,-0.6)
# maybe from a linear regression of mean annual air temperature (MAAT)[也许从一元线性回归的年平均气温（MAAT）]
# against elevation - something like:[对高度 - 是这样的：]
# coefs = coef( lm( maat ~ elevation ) )[COEFS系数（LM（MAAT高程））]
rsaga.linear.combination("elevation.sgrd", "maat.sgrd", coefs)
# equivalent:[相当于：]
rsaga.grid.calculus("elevation.sgrd", "maat.sgrd", ~ 20 - 0.6*a)
转载请注明:出自 生物统计家园网(http://www.biostatistic.net)。
注：
注1：为了方便大家学习，本文档为生物统计家园网机器人LoveR翻译而成，仅供个人R语言学习参考使用，生物统计家园保留版权。
注2：由于是机器人自动翻译，难免有不准确之处，使用时仔细对照中、英文内容进行反复理解，可以帮助R语言的学习。
注3：如遇到不准确之处，请在本贴的后面进行回帖，我们会逐渐进行修订。
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发表于 2012-9-28 21:19:06
