blocks|key|1731003|text|这基本上使用了与Tommy相同的解决方案，但使用Map()时，不需要访问存储列表组件名称的全局变量。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1731004|>+x+<-+list(a=11,+b=12,+c=13)
>+Map(function(x,+i)+paste(i,+x),+x,+names(x))
$a
[1]+"a+11"

$b
[1]+"b+12"

$c
[1]+"c+13|code-block|syntax|javascript|1731005|或者，如果您更喜欢mapply()|1731006|>+mapply(function(x,+i)+paste(i,+x),+x,+names(x))
+++++a++++++b++++++c+
"a+11"+"b+12"+"c+13"|1731007|entityMap^0|O|5|0|0|9|8|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@$9|R|A|S|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|T|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|U|8|@$9|V|A|W|B|C]]|D|@]|E|$]]|$1|M|3|N|5|H|7|X|8|@]|D|@]|E|$I|J]]|$1|O|3|-4|5|6|7|Y|8|@]|D|@]|E|$]]]|P|$]]

This basically uses the same workaround as Tommy, but with <code>Map()</code>, there's no need to access global variables which store the names of list components.

<pre><code>&gt; x &lt;- list(a=11, b=12, c=13)
&gt; Map(function(x, i) paste(i, x), x, names(x))
$a
[1] "a 11"

$b
[1] "b 12"

$c
[1] "c 13
</code></pre>

Or, if you prefer <code>mapply()</code>

<pre><code>&gt; mapply(function(x, i) paste(i, x), x, names(x))
 a b c 
"a 11" "b 12" "c 13"
</code></pre>

blocks|key|1731130|text|我已经有很多次同样的问题了。我开始用另一种方式...我开始使用mapply，而不是使用lapply|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1731131|n+=+names(mylist)
mapply(function(list.elem,+names)+{+},+list.elem+=+mylist,+names+=+n)|code-block|syntax|javascript|1731132|entityMap^0|V|6|17|6|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]|$9|P|A|Q|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|R|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|S|8|@]|D|@]|E|$]]]|L|$]]

I've had the same problem a lot of times... 
I've started using another way... Instead of using <code>lapply</code>, I've started using <code>mapply</code>

<pre><code>n = names(mylist)
mapply(function(list.elem, names) { }, list.elem = mylist, names = n)
</code></pre>

blocks|key|1731176|text|只需循环输入名称即可。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1731177|sapply(names(mylist),+function(n)+{+
++++doSomething(mylist[[n]])
++++cat(n,+'\n')
}|code-block|syntax|javascript|1731178|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Just loop in the names.

<pre><code>sapply(names(mylist), function(n) { 
 doSomething(mylist[[n]])
 cat(n, '\n')
}
</code></pre>

blocks|key|1944326|text|Tommy的回答适用于命名向量，但我知道您对列表感兴趣。而且看起来他似乎是在做一个结束，因为他引用了调用环境中的"x“。此函数仅使用传递给函数的参数，因此对传递的对象名称没有任何假设：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1944327|x+<-+list(a=11,b=12,c=13)
lapply(x,+function(z)+{+attributes(deparse(substitute(z)))$names++}+)
#--------
$a
NULL

$b
NULL

$c
NULL
#--------
+names(+lapply(x,+function(z)+{+attributes(deparse(substitute(z)))$names++}+))
#[1]+"a"+"b"+"c"
+what_is_my_name+<-+function(ZZZ)+return(deparse(substitute(ZZZ)))
+what_is_my_name(X)
#[1]+"X"
what_is_my_name(ZZZ=this)
#[1]+"this"
+exists("this")
#[1]+FALSE|code-block|syntax|javascript|1944328|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Tommy's answer applies to named vectors but I got the idea you were interested in lists. And it seems as though he were doing an end-around because he was referencing "x" from the calling environment. This function uses only the parameters that were passed to the function and so makes no assumptions about the name of objects that were passed:

<pre><code>x &lt;- list(a=11,b=12,c=13)
lapply(x, function(z) { attributes(deparse(substitute(z)))$names } )
#--------
$a
NULL

$b
NULL

$c
NULL
#--------
 names( lapply(x, function(z) { attributes(deparse(substitute(z)))$names } ))
#[1] "a" "b" "c"
 what_is_my_name &lt;- function(ZZZ) return(deparse(substitute(ZZZ)))
 what_is_my_name(X)
#[1] "X"
what_is_my_name(ZZZ=this)
#[1] "this"
 exists("this")
#[1] FALSE
</code></pre>

blocks|key|1944414|text|我的答案与Tommy的和caracals的方向相同，但避免了将列表保存为附加对象。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1944415|lapply(seq(3),+function(i,+y=list(a=14,b=15,c=16))+{+paste(names(y)[[i]],+y[[i]])+})|code-block|syntax|javascript|1944416|结果：|1944417|[[1]]
[1]+"a+14"

[[2]]
[1]+"b+15"

[[3]]
[1]+"c+16"|1944418|这会将列表作为一个命名参数提供给FUN+(而不是lapply)。lapply只需遍历列表的元素(在更改列表的长度时，请注意将第一个参数更改为lapply+)。|1944419|注意:将列表作为附加参数直接提供给lapply也是可行的：|1944420|lapply(seq(3),+function(i,+y)+{+paste(names(y)[[i]],+y[[i]])+},+y=list(a=14,b=15,c=16))|1944421|entityMap^0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|U|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|W|8|@]|9|@]|A|$]]|$1|M|3|N|5|6|7|X|8|@]|9|@]|A|$]]|$1|O|3|P|5|D|7|Y|8|@]|9|@]|A|$E|F]]|$1|Q|3|-4|5|6|7|Z|8|@]|9|@]|A|$]]]|R|$]]

My answer goes in the same direction as Tommy's and caracals, but avoids having to save the list as an additional object. 

<pre><code>lapply(seq(3), function(i, y=list(a=14,b=15,c=16)) { paste(names(y)[[i]], y[[i]]) })
</code></pre>

Result: 

<pre><code>[[1]]
[1] "a 14"

[[2]]
[1] "b 15"

[[3]]
[1] "c 16"
</code></pre>

This gives the list as a named argument to FUN (instead to lapply). lapply only has to iterate over the elements of the list (be careful to change this first argument to lapply when changing the length of the list).

Note: Giving the list directly to lapply as an additional argument also works: 

<pre><code>lapply(seq(3), function(i, y) { paste(names(y)[[i]], y[[i]]) }, y=list(a=14,b=15,c=16))
</code></pre>

blocks|key|1944937|text|@caracals和@Tommy都是很好的解决方案，这是一个包括list和data.frame的例子。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1944938|r是list和data.frame的list+(末尾是dput(r[[1]])。|1944939|names(r)
[1]+"todos"++"random"
r[[1]][1]
$F0
$F0$rst1
+++algo++rst++prec++rorac+prPo+pos
1++Mean+56.4+0.450+25.872+91.2+239
6++gbm1+41.8+0.438+22.595+77.4+239
4++GAM2+37.2+0.512+43.256+50.0+172
7++gbm2+36.8+0.422+18.039+85.4+239
11+ran2+35.0+0.442+23.810+61.5+239
2++nai1+29.8+0.544+52.281+33.1+172
5++GAM3+28.8+0.403+12.743+94.6+239
3++GAM1+21.8+0.405+13.374+68.2+239
10+ran1+19.4+0.406+13.566+59.8+239
9++svm2+14.0+0.385++7.692+76.2+239
8++svm1++0.8+0.359++0.471+71.1+239

$F0$rst5
+++algo++rst++prec++rorac+prPo+pos
1++Mean+52.4+0.441+23.604+92.9+239
7++gbm2+46.4+0.440+23.200+83.7+239
6++gbm1+31.2+0.416+16.421+79.5+239
5++GAM3+28.8+0.403+12.743+94.6+239
4++GAM2+28.2+0.481+34.815+47.1+172
11+ran2+26.6+0.422+18.095+61.5+239
2++nai1+23.6+0.519+45.385+30.2+172
3++GAM1+20.6+0.398+11.381+75.7+239
9++svm2+14.4+0.386++8.182+73.6+239
10+ran1+14.0+0.390++9.091+64.4+239
8++svm1++6.2+0.370++3.584+72.4+239|code-block|syntax|javascript|1944940|目标是unlist所有列表，将list的名称序列作为一列来标识大小写。|1944941|r=unlist(unlist(r,F),F)
names(r)
[1]+"todos.F0.rst1"++"todos.F0.rst5"++"todos.T0.rst1"++"todos.T0.rst5"++"random.F0.rst1"+"random.F0.rst5"
[7]+"random.T0.rst1"+"random.T0.rst5"|1944942|取消列出列表，但不要列出data.frame。|1944943|ra=Reduce(rbind,Map(function(x,y)+cbind(case=x,y),names(r),r))|1944944|Map将名称序列放在一列中。Reduce加入所有data.frame‘s。|1944945|head(ra)
++++++++++++case+algo++rst++prec++rorac+prPo+pos
1++todos.F0.rst1+Mean+56.4+0.450+25.872+91.2+239
6++todos.F0.rst1+gbm1+41.8+0.438+22.595+77.4+239
4++todos.F0.rst1+GAM2+37.2+0.512+43.256+50.0+172
7++todos.F0.rst1+gbm2+36.8+0.422+18.039+85.4+239
11+todos.F0.rst1+ran2+35.0+0.442+23.810+61.5+239
2++todos.F0.rst1+nai1+29.8+0.544+52.281+33.1+172|1944946|附注：r[[1]]：|1944947|++++structure(list(F0+=+structure(list(rst1+=+structure(list(algo+=+c("Mean",+
++++"gbm1",+"GAM2",+"gbm2",+"ran2",+"nai1",+"GAM3",+"GAM1",+"ran1",+
++++"svm2",+"svm1"),+rst+=+c(56.4,+41.8,+37.2,+36.8,+35,+29.8,+28.8,+
++++21.8,+19.4,+14,+0.8),+prec+=+c(0.45,+0.438,+0.512,+0.422,+0.442,+
++++0.544,+0.403,+0.405,+0.406,+0.385,+0.359),+rorac+=+c(25.872,+
++++22.595,+43.256,+18.039,+23.81,+52.281,+12.743,+13.374,+13.566,+
++++7.692,+0.471),+prPo+=+c(91.2,+77.4,+50,+85.4,+61.5,+33.1,+94.6,+
++++68.2,+59.8,+76.2,+71.1),+pos+=+c(239L,+239L,+172L,+239L,+239L,+
++++172L,+239L,+239L,+239L,+239L,+239L)),+.Names+=+c("algo",+"rst",+
++++"prec",+"rorac",+"prPo",+"pos"),+row.names+=+c(1L,+6L,+4L,+7L,+
++++11L,+2L,+5L,+3L,+10L,+9L,+8L),+class+=+"data.frame"),+rst5+=+structure(list(
++++++++algo+=+c("Mean",+"gbm2",+"gbm1",+"GAM3",+"GAM2",+"ran2",+
++++++++"nai1",+"GAM1",+"svm2",+"ran1",+"svm1"),+rst+=+c(52.4,+46.4,+
++++++++31.2,+28.8,+28.2,+26.6,+23.6,+20.6,+14.4,+14,+6.2),+prec+=+c(0.441,+
++++++++0.44,+0.416,+0.403,+0.481,+0.422,+0.519,+0.398,+0.386,+0.39,+
++++++++0.37),+rorac+=+c(23.604,+23.2,+16.421,+12.743,+34.815,+18.095,+
++++++++45.385,+11.381,+8.182,+9.091,+3.584),+prPo+=+c(92.9,+83.7,+
++++++++79.5,+94.6,+47.1,+61.5,+30.2,+75.7,+73.6,+64.4,+72.4),+pos+=+c(239L,+
++++++++239L,+239L,+239L,+172L,+239L,+172L,+239L,+239L,+239L,+239L
++++++++)),+.Names+=+c("algo",+"rst",+"prec",+"rorac",+"prPo",+"pos"
++++),+row.names+=+c(1L,+7L,+6L,+5L,+4L,+11L,+2L,+3L,+9L,+10L,+8L
++++),+class+=+"data.frame")),+.Names+=+c("rst1",+"rst5")),+T0+=+structure(list(
++++++++rst1+=+structure(list(algo+=+c("Mean",+"ran1",+"GAM1",+"GAM2",+
++++++++"gbm1",+"svm1",+"nai1",+"gbm2",+"svm2",+"ran2"),+rst+=+c(22.6,+
++++++++19.4,+13.6,+10.2,+9.6,+8,+5.6,+3.4,+-0.4,+-0.6),+prec+=+c(0.478,+
++++++++0.452,+0.5,+0.421,+0.423,+0.833,+0.429,+0.373,+0.355,+0.356
++++++++),+rorac+=+c(33.731,+26.575,+40,+17.895,+18.462,+133.333,+
++++++++20,+4.533,+-0.526,+-0.368),+prPo+=+c(34.4,+52.1,+24.3,+40.7,+
++++++++37.1,+3.1,+14.4,+53.6,+54.3,+116.4),+pos+=+c(195L,+140L,+
++++++++140L,+140L,+140L,+195L,+195L,+140L,+140L,+140L)),+.Names+=+c("algo",+
++++++++"rst",+"prec",+"rorac",+"prPo",+"pos"),+row.names+=+c(1L,+
++++++++9L,+3L,+4L,+5L,+7L,+2L,+6L,+8L,+10L),+class+=+"data.frame"),+
++++++++rst5+=+structure(list(algo+=+c("gbm1",+"ran1",+"Mean",+"GAM1",+
++++++++"GAM2",+"svm1",+"nai1",+"svm2",+"gbm2",+"ran2"),+rst+=+c(17.6,+
++++++++16.4,+15,+12.8,+9,+6.2,+5.8,+-2.6,+-3,+-9.2),+prec+=+c(0.466,+
++++++++0.434,+0.435,+0.5,+0.41,+0.8,+0.44,+0.346,+0.345,+0.337),+
++++++++++++rorac+=+c(30.345,+21.579,+21.739,+40,+14.754,+124,+23.2,+
++++++++++++-3.21,+-3.448,+-5.542),+prPo+=+c(41.4,+54.3,+35.4,+22.9,+
++++++++++++43.6,+2.6,+12.8,+57.9,+62.1,+118.6),+pos+=+c(140L,+140L,+
++++++++++++195L,+140L,+140L,+195L,+195L,+140L,+140L,+140L)),+.Names+=+c("algo",+
++++++++"rst",+"prec",+"rorac",+"prPo",+"pos"),+row.names+=+c(5L,+
++++++++9L,+1L,+3L,+4L,+7L,+2L,+8L,+6L,+10L),+class+=+"data.frame")),+.Names+=+c("rst1",+
++++"rst5"))),+.Names+=+c("F0",+"T0"))|1944948|entityMap^0|W|4|11|A|0|0|1|2|4|7|A|I|4|R|B|0|0|3|6|F|4|0|0|C|A|0|0|0|3|E|6|O|A|0|0|3|6|0|0^^$0|@$1|2|3|4|5|6|7|14|8|@$9|15|A|16|B|C]|$9|17|A|18|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|19|8|@$9|1A|A|1B|B|C]|$9|1C|A|1D|B|C]|$9|1E|A|1F|B|C]|$9|1G|A|1H|B|C]|$9|1I|A|1J|B|C]]|D|@]|E|$]]|$1|H|3|I|5|J|7|1K|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|1L|8|@$9|1M|A|1N|B|C]|$9|1O|A|1P|B|C]]|D|@]|E|$]]|$1|O|3|P|5|J|7|1Q|8|@]|D|@]|E|$K|L]]|$1|Q|3|R|5|6|7|1R|8|@$9|1S|A|1T|B|C]]|D|@]|E|$]]|$1|S|3|T|5|J|7|1U|8|@]|D|@]|E|$K|L]]|$1|U|3|V|5|6|7|1V|8|@$9|1W|A|1X|B|C]|$9|1Y|A|1Z|B|C]|$9|20|A|21|B|C]]|D|@]|E|$]]|$1|W|3|X|5|J|7|22|8|@]|D|@]|E|$K|L]]|$1|Y|3|Z|5|6|7|23|8|@$9|24|A|25|B|C]]|D|@]|E|$]]|$1|10|3|11|5|J|7|26|8|@]|D|@]|E|$K|L]]|$1|12|3|-4|5|6|7|27|8|@]|D|@]|E|$]]]|13|$]]

Both @caracals and @Tommy are good solutions and this is an example including <code>list</code>´s and <code>data.frame</code>´s. 
<code>r</code> is a <code>list</code> of <code>list</code>´s and <code>data.frame</code>´s (<code>dput(r[[1]]</code> at the end). 

<pre><code>names(r)
[1] "todos" "random"
r[[1]][1]
$F0
$F0$rst1
 algo rst prec rorac prPo pos
1 Mean 56.4 0.450 25.872 91.2 239
6 gbm1 41.8 0.438 22.595 77.4 239
4 GAM2 37.2 0.512 43.256 50.0 172
7 gbm2 36.8 0.422 18.039 85.4 239
11 ran2 35.0 0.442 23.810 61.5 239
2 nai1 29.8 0.544 52.281 33.1 172
5 GAM3 28.8 0.403 12.743 94.6 239
3 GAM1 21.8 0.405 13.374 68.2 239
10 ran1 19.4 0.406 13.566 59.8 239
9 svm2 14.0 0.385 7.692 76.2 239
8 svm1 0.8 0.359 0.471 71.1 239

$F0$rst5
 algo rst prec rorac prPo pos
1 Mean 52.4 0.441 23.604 92.9 239
7 gbm2 46.4 0.440 23.200 83.7 239
6 gbm1 31.2 0.416 16.421 79.5 239
5 GAM3 28.8 0.403 12.743 94.6 239
4 GAM2 28.2 0.481 34.815 47.1 172
11 ran2 26.6 0.422 18.095 61.5 239
2 nai1 23.6 0.519 45.385 30.2 172
3 GAM1 20.6 0.398 11.381 75.7 239
9 svm2 14.4 0.386 8.182 73.6 239
10 ran1 14.0 0.390 9.091 64.4 239
8 svm1 6.2 0.370 3.584 72.4 239
</code></pre>

The objective is to <code>unlist</code> all lists, putting the sequence of <code>list</code>´s names as a columns to identify the case. 

<pre><code>r=unlist(unlist(r,F),F)
names(r)
[1] "todos.F0.rst1" "todos.F0.rst5" "todos.T0.rst1" "todos.T0.rst5" "random.F0.rst1" "random.F0.rst5"
[7] "random.T0.rst1" "random.T0.rst5"
</code></pre>

Unlist the lists but not the <code>data.frame</code> ´s. 

<pre><code>ra=Reduce(rbind,Map(function(x,y) cbind(case=x,y),names(r),r))
</code></pre>

<code>Map</code> puts the sequence of names as a column. <code>Reduce</code> join all <code>data.frame</code>´s. 

<pre><code>head(ra)
 case algo rst prec rorac prPo pos
1 todos.F0.rst1 Mean 56.4 0.450 25.872 91.2 239
6 todos.F0.rst1 gbm1 41.8 0.438 22.595 77.4 239
4 todos.F0.rst1 GAM2 37.2 0.512 43.256 50.0 172
7 todos.F0.rst1 gbm2 36.8 0.422 18.039 85.4 239
11 todos.F0.rst1 ran2 35.0 0.442 23.810 61.5 239
2 todos.F0.rst1 nai1 29.8 0.544 52.281 33.1 172
</code></pre>

P.S. <code>r[[1]]</code>: 

<pre><code> structure(list(F0 = structure(list(rst1 = structure(list(algo = c("Mean", 
 "gbm1", "GAM2", "gbm2", "ran2", "nai1", "GAM3", "GAM1", "ran1", 
 "svm2", "svm1"), rst = c(56.4, 41.8, 37.2, 36.8, 35, 29.8, 28.8, 
 21.8, 19.4, 14, 0.8), prec = c(0.45, 0.438, 0.512, 0.422, 0.442, 
 0.544, 0.403, 0.405, 0.406, 0.385, 0.359), rorac = c(25.872, 
 22.595, 43.256, 18.039, 23.81, 52.281, 12.743, 13.374, 13.566, 
 7.692, 0.471), prPo = c(91.2, 77.4, 50, 85.4, 61.5, 33.1, 94.6, 
 68.2, 59.8, 76.2, 71.1), pos = c(239L, 239L, 172L, 239L, 239L, 
 172L, 239L, 239L, 239L, 239L, 239L)), .Names = c("algo", "rst", 
 "prec", "rorac", "prPo", "pos"), row.names = c(1L, 6L, 4L, 7L, 
 11L, 2L, 5L, 3L, 10L, 9L, 8L), class = "data.frame"), rst5 = structure(list(
 algo = c("Mean", "gbm2", "gbm1", "GAM3", "GAM2", "ran2", 
 "nai1", "GAM1", "svm2", "ran1", "svm1"), rst = c(52.4, 46.4, 
 31.2, 28.8, 28.2, 26.6, 23.6, 20.6, 14.4, 14, 6.2), prec = c(0.441, 
 0.44, 0.416, 0.403, 0.481, 0.422, 0.519, 0.398, 0.386, 0.39, 
 0.37), rorac = c(23.604, 23.2, 16.421, 12.743, 34.815, 18.095, 
 45.385, 11.381, 8.182, 9.091, 3.584), prPo = c(92.9, 83.7, 
 79.5, 94.6, 47.1, 61.5, 30.2, 75.7, 73.6, 64.4, 72.4), pos = c(239L, 
 239L, 239L, 239L, 172L, 239L, 172L, 239L, 239L, 239L, 239L
 )), .Names = c("algo", "rst", "prec", "rorac", "prPo", "pos"
 ), row.names = c(1L, 7L, 6L, 5L, 4L, 11L, 2L, 3L, 9L, 10L, 8L
 ), class = "data.frame")), .Names = c("rst1", "rst5")), T0 = structure(list(
 rst1 = structure(list(algo = c("Mean", "ran1", "GAM1", "GAM2", 
 "gbm1", "svm1", "nai1", "gbm2", "svm2", "ran2"), rst = c(22.6, 
 19.4, 13.6, 10.2, 9.6, 8, 5.6, 3.4, -0.4, -0.6), prec = c(0.478, 
 0.452, 0.5, 0.421, 0.423, 0.833, 0.429, 0.373, 0.355, 0.356
 ), rorac = c(33.731, 26.575, 40, 17.895, 18.462, 133.333, 
 20, 4.533, -0.526, -0.368), prPo = c(34.4, 52.1, 24.3, 40.7, 
 37.1, 3.1, 14.4, 53.6, 54.3, 116.4), pos = c(195L, 140L, 
 140L, 140L, 140L, 195L, 195L, 140L, 140L, 140L)), .Names = c("algo", 
 "rst", "prec", "rorac", "prPo", "pos"), row.names = c(1L, 
 9L, 3L, 4L, 5L, 7L, 2L, 6L, 8L, 10L), class = "data.frame"), 
 rst5 = structure(list(algo = c("gbm1", "ran1", "Mean", "GAM1", 
 "GAM2", "svm1", "nai1", "svm2", "gbm2", "ran2"), rst = c(17.6, 
 16.4, 15, 12.8, 9, 6.2, 5.8, -2.6, -3, -9.2), prec = c(0.466, 
 0.434, 0.435, 0.5, 0.41, 0.8, 0.44, 0.346, 0.345, 0.337), 
 rorac = c(30.345, 21.579, 21.739, 40, 14.754, 124, 23.2, 
 -3.21, -3.448, -5.542), prPo = c(41.4, 54.3, 35.4, 22.9, 
 43.6, 2.6, 12.8, 57.9, 62.1, 118.6), pos = c(140L, 140L, 
 195L, 140L, 140L, 195L, 195L, 140L, 140L, 140L)), .Names = c("algo", 
 "rst", "prec", "rorac", "prPo", "pos"), row.names = c(5L, 
 9L, 1L, 3L, 4L, 7L, 2L, 8L, 6L, 10L), class = "data.frame")), .Names = c("rst1", 
 "rst5"))), .Names = c("F0", "T0"))
</code></pre>

blocks|key|1731668|text|假设我们想要计算每个元素的长度。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1731669|mylist+<-+list(a=1:4,b=2:9,c=10:20)
mylist

$a
[1]+1+2+3+4

$b
[1]+2+3+4+5+6+7+8+9

$c
+[1]+10+11+12+13+14+15+16+17+18+19+20|code-block|syntax|javascript|1731670|如果目标只是标记结果元素，那么lapply(mylist,length)或更低版本就可以了。|offset|length|style|CODE|1731671|sapply(mylist,length,USE.NAMES=T)

+a++b++c+
+4++8+11+|1731672|如果目的是在函数中使用标签，那么mapply()可以通过循环遍历两个对象来实现:列表元素和列表名称。|1731673|fun+<-+function(x,y)+paste0(length(x),"_",y)
mapply(fun,mylist,names(mylist))

+++++a++++++b++++++c+
+"4_a"++"8_b"+"11_c"+|1731674|entityMap^0|0|0|F|L|0|0|G|8|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|W|8|@$I|X|J|Y|K|L]]|9|@]|A|$]]|$1|M|3|N|5|D|7|Z|8|@]|9|@]|A|$E|F]]|$1|O|3|P|5|6|7|10|8|@$I|11|J|12|K|L]]|9|@]|A|$]]|$1|Q|3|R|5|D|7|13|8|@]|9|@]|A|$E|F]]|$1|S|3|-4|5|6|7|14|8|@]|9|@]|A|$]]]|T|$]]

Let's say we want to calculate length of each element.

<pre><code>mylist &lt;- list(a=1:4,b=2:9,c=10:20)
mylist

$a
[1] 1 2 3 4

$b
[1] 2 3 4 5 6 7 8 9

$c
 [1] 10 11 12 13 14 15 16 17 18 19 20
</code></pre>

If the aim is to just label the resulting elements, then <code>lapply(mylist,length)</code> or below works.

<pre><code>sapply(mylist,length,USE.NAMES=T)

 a b c 
 4 8 11 
</code></pre>

If the aim is to use the label inside the function, then <code>mapply()</code> is useful by looping over two objects; the list elements and list names.

<pre><code>fun &lt;- function(x,y) paste0(length(x),"_",y)
mapply(fun,mylist,names(mylist))

 a b c 
 "4_a" "8_b" "11_c" 
</code></pre>

blocks|key|1944720|text|只需编写您自己的自定义lapply函数|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1944721|lapply2+<-+function(X,+FUN){
++if(+length(formals(FUN))+==+1+){
++++#+No+index+passed+-+use+normal+lapply
++++R+=+lapply(X,+FUN)
++}else{
++++#+Index+passed
++++R+=+lapply(seq_along(X),+FUN=function(i){
++++++FUN(X[[i]],+i)
++++})
++}

++#+Set+names
++names(R)+=+names(X)
++return(R)
}|code-block|syntax|javascript|1944722|然后像这样使用：|1944723|lapply2(letters,+function(x,+i)+paste(x,+i))|1944724|entityMap^0|B|6|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@$9|R|A|S|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|T|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|U|8|@]|D|@]|E|$]]|$1|M|3|N|5|H|7|V|8|@]|D|@]|E|$I|J]]|$1|O|3|-4|5|6|7|W|8|@]|D|@]|E|$]]]|P|$]]

Just write your own custom <code>lapply</code> function

<pre><code>lapply2 &lt;- function(X, FUN){
 if( length(formals(FUN)) == 1 ){
 # No index passed - use normal lapply
 R = lapply(X, FUN)
 }else{
 # Index passed
 R = lapply(seq_along(X), FUN=function(i){
 FUN(X[[i]], i)
 })
 }

 # Set names
 names(R) = names(X)
 return(R)
}
</code></pre>

Then use like this:

<pre><code>lapply2(letters, function(x, i) paste(x, i))
</code></pre>

Is there a way to get the list index name in my lapply() function?

<pre><code>n = names(mylist)
lapply(mylist, function(list.elem) { cat("What is the name of this list element?\n" })
</code></pre>

I asked <a href="https://stackoverflow.com/questions/9469504/access-and-preserve-list-names-in-lapply-function">before</a> if it's possible to preserve the index names in the lapply() returned list, but I still don't know if there is an easy way to fetch each element name inside the custom function. I would like to avoid to call lapply on the names themselves, I'd rather get the name in the function parameters.

Access lapply index names inside FUN

有没有办法在我的lapply()函数中获得列表索引名？n = names(mylist)lapply(mylist, function(list.elem) { cat("What is the name of this list element?\n" })我问是否可以在lapply()返回的列表中保留索引名，但我仍然不知道是否有一种简单的方法来获取定制函数中的每个元素名。我希望避免对名称本身调

问访问lapply索引名称inside FUN
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回答 8

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