在每行数据帧上调用类似应用程序的函数,每行有多个参数 [英] Call apply-like function on each row of dataframe with multiple arguments from each row
问题描述
> df< - data.frame(x = c(1,2),y = c(3,4),z = c(5,6))
> df
x y z
1 1 3 5
2 2 4 6
> testFunc< - 函数(a,b)a + b
到x和z列。所以,对于行1,我想要1 + 5,对于行2,我想要2 + 6。有没有办法做这个没有写一个for循环,也许与应用功能的家庭?
我尝试过:
> df [,c('x','z')]
x z
1 1 5
2 2 6
> lapply(df [,c('x','z')],testFunc)
+ b中的错误:'b'缺少
但是有错误,任何想法?
编辑:我想要的实际功能电话不是一个简单的总和,但它是power.t.test。我用一个+ b为例。最终目标是能够做这样的事情(用伪代码写成):
df = data.frame(
delta = c(delta_values),
power = c(power_values),
sig.level = c(sig.level_values)
)
lapply ,power.t.test(delta_from_each_row_of_df,
power_from_each_row_of_df,
sig.level_from_each_row_of_df
))
其中结果是df的每一行的power.t.test的输出向量。
p>您可以将 apply
应用于原始数据的一部分。
dat <,data()(x = c(1,2),y = c(3,4),z = c(5,6))
apply ,'z')],1,function(x)sum(x))
函数只是使用向量化版本的总和:
rowSums(dat [,c('x','z')])
[1] 6 8
如果你想要使用 testFunc
testFunc< - function(a,b )a + b
apply(dat [,c('x','z')],1,function(x)testFunc(x [1],x [2]))
编辑要按名称访问列,而不是索引,您可以执行以下操作:
testFunc< - function(a,b)a + b
apply(dat [,c('x','z ')],1,function(y)testFunc(y ['z'],y ['x']))
I have a dataframe with multiple columns. For each row in the dataframe, I want to call a function on the row, and the input of the function is using multiple columns from that row. For example, let's say I have this data and this testFunc which accepts two args:
> df <- data.frame(x=c(1,2), y=c(3,4), z=c(5,6))
> df
x y z
1 1 3 5
2 2 4 6
> testFunc <- function(a, b) a + b
Let's say I want to apply this testFunc to columns x and z. So, for row 1 I want 1+5, and for row 2 I want 2 + 6. Is there a way to do this without writing a for loop, maybe with the apply function family?
I tried this:
> df[,c('x','z')]
x z
1 1 5
2 2 6
> lapply(df[,c('x','z')], testFunc)
Error in a + b : 'b' is missing
But got error, any ideas?
EDIT: the actual function I want to call is not a simple sum, but it is power.t.test. I used a+b just for example purposes. The end goal is to be able to do something like this (written in pseudocode):
df = data.frame(
delta=c(delta_values),
power=c(power_values),
sig.level=c(sig.level_values)
)
lapply(df, power.t.test(delta_from_each_row_of_df,
power_from_each_row_of_df,
sig.level_from_each_row_of_df
))
where the result is a vector of outputs for power.t.test for each row of df.
You can apply apply
to a subset of the original data.
dat <- data.frame(x=c(1,2), y=c(3,4), z=c(5,6))
apply(dat[,c('x','z')], 1, function(x) sum(x) )
or if your function is just sum use the vectorized version:
rowSums(dat[,c('x','z')])
[1] 6 8
If you want to use testFunc
testFunc <- function(a, b) a + b
apply(dat[,c('x','z')], 1, function(x) testFunc(x[1],x[2]))
EDIT To access columns by name and not index you can do something like this:
testFunc <- function(a, b) a + b
apply(dat[,c('x','z')], 1, function(y) testFunc(y['z'],y['x']))
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